| Author |
Message |
    
Patrick Lockyer.
Frequent User
Username: pat_lockyer
Post Number: 28
Registered: 9-2004
| | Posted on Saturday, 30 October, 2004 - 09:36 am: |    |
Back from hols,and just to put my few words on the subject.
Yes there is a weakness in them and a great number of other manufactures ones as well.
However only mostly brought about by little or faulty maintence ,this seems not to have been mentioned on this forum so far.
1.incorrect torque setting of the locating nut on the rocking shaft over time.
Should be released and retorqued every couple of years to 200lb.ft
2.Wheel dynamic out of balance.
3.brake disc distortion.
4.Tyre run out and flat spots.
All these probs if not delt with will cause stress movement on the taper with failure of the arm and yes even with the later type arm.
Do not get paranoid about failures if the above are carried out and delt with in the maintenance schedule times no failures will occur even after many years and miles.
The uk annual mot test,it is also a requirement to check and test for any faults with the arms.
|
Richard Treacy
Grand Master
Username: richard_treacy
Post Number: 408
Registered: 4-2003
| | Posted on Monday, 01 November, 2004 - 03:17 am: | |
Now that this Pitman arm topic has its own thread, can I pose a few questions.
Pat don't take this as hostile in any way, but:
This is surely no maintenance issue.
You cannot seriously suggest that a 5 year old car should have its Pitman maintained. Nor should a car of 105 years of age. Most Shadows were 5 years old when their drop arm levers failed. Ours happened to be 28: a well cared for car, and I can assure you that the steering box had never been touched. There is a downright design fault in these Pitman arms.
Sorry.
As for the UK MOT, you are lucky if they kick the tyres. It is a complete joke. Rust: no problem, oil leaks: no problem, steering play: no problem. Having seen many UK cars, R-R included, with new MOT I have no respect for the quality of the tests.
The most thorough test in Australia was always in the ACT (Canberra), but they gave up as it was too expensive and most cars were too new or well kept to fail anyhow. It is now a random check system: never park a defective vehicle in a car park or you may return to find a defect notice on your windscreen if you even have just rust bubbles. I hated the thorought ACT yearly tests, but they served a purpose.
I have been accused before of poor maintenance causing this failure. I think it absurd that I should ever need to re-torque such a fundamental safety component during maintenance. That would be a world first. No respectful engineer would include that in a scheduled maintenance regime. These cars should have been recalled as a "A" matter, ie obligatory and urgent, in my opinion. Any other manufacturer would have done so. The same applies to the final drive crossmember. Instead, the changed pitman arm design, revised final drive crossmember and reinforced final drive torque arm were all modified without reference in any service bulletin. Our final drive crossmember was modified around 1977 by the main dealer with no entry into the service records and no invoice. Make up your own mind.
Robert C., if you read this, you say you have found three cracked Pitman arms recently. Out of how many tested was that ? Out of interest, are you prepared to say how you detected the cracks (magnaflux, X-ray, ultrasound, infrared etc) ? I will understand if you decline to do so of course.
In any case, I can assure any reader that Robert is providing a really important service here, and is certainly not trying to drum up business. If you have ever experienced a sudden loss of steering, or any other fundamental loss of control, you will certainly understand. |
Patrick Lockyer.
Prolific User
Username: pat_lockyer
Post Number: 33
Registered: 9-2004
| | Posted on Monday, 01 November, 2004 - 07:26 am: | |
Richard it is in my opinon that it is a must to have any of the above delt with strait away or certainly in the maintenace schedule.
As i have said there is a weekness there and any vibration on the steering puts loading to eventual
stess movment on the joint.
I am not implying that any one is trying to drum up business through not doing the checks and having failures.
As for the mot checks i am sure you are out of date on the proceedure in the uk.
If you know diferent i would only be to pleased to have the testing station no and discipline i assure you will be followed up. |
Richard Treacy
Grand Master
Username: richard_treacy
Post Number: 409
Registered: 4-2003
| | Posted on Monday, 01 November, 2004 - 07:54 am: | |
Hello Pat,
Again, not trying to be aggressive, but I can e-mail you a 2003 letter from the MOT to me after I complained about their negligent practices. It will stun you. All care, no responsibility etc.
I don't believe that over the last 18 months' a revolution has occurred in the MOT.
eg Point 4 of the letter:
"4. The sale of unroadworthy vehicles present (sic) difficult problems since offences are not normally discovered until after the vehicle has been finally purchased. It is the Department's policy to advise the buyers of used vehicles that the most effective measures they can take to protect themselves is to have the vehicle thoroughly examined before completing the purchase.".
This was after a car (not mine, but a 7-year-old Bentley nevertheless), was passed by the MOT before purchase, and then immediately banned from use the next day by the police. The 18 month West London comprehensive warranty was practically useless.
This chief really means that the MOT is for nothing: you must have an independent test, and the MOT takes no responsibility for roadworthiness at all. |
Richard Treacy
Grand Master
Username: richard_treacy
Post Number: 410
Registered: 4-2003
| | Posted on Monday, 01 November, 2004 - 08:32 am: | |
Basic stuff:
Front brake rotors more than 3mm worn. Steering rack leaking (unfortunately common) and too much play, rear road spring supports rotten, seatbelt missing from the centre rear, heater inoperative, damaged fuel lines. The police noted the seat belt problem, and the subsequent check revealed the rest.
The non-safety items were something else, and all in a fairly new car. Company car for sure. |
Patrick Lockyer.
Prolific User
Username: pat_lockyer
Post Number: 34
Registered: 9-2004
| | Posted on Monday, 01 November, 2004 - 09:08 am: | |
Richard.
I forgot to mention bump steer on rough roads it is a killer for the pitman arm and another important item to be delt with in the service schedule.
Will get back on the mot failings |
Robert Chapman
Prolific User
Username: shadow
Post Number: 98
Registered: 5-2003
| | Posted on Monday, 01 November, 2004 - 11:07 am: | |
Pat Lockyer.
This latest fallacious post of yours is really verging on professionally irresponsible.
Even on such a serious safety subject as this you cannot control your puerile and transparent obsession to contradict
Your contrived suggestion that this failure can be prevented by a change of service schedule is grossly misleading and could put owners and other road users lives at risk.
Your statement that even the new design arms can fail if not “maintained” is blatantly incorrect.
The dangerous thing is that you are prepared to make such categorical authoritarian statements as
”no failures will occur” on this forum and that some owners / readers may take your advise seriously.
I believe the contents of this post is grossly irresponsible, I think you should remember that peoples safety could be put at risk by your self serving advice and that any safety related advice needs to be absolutely correct.
|
John Dare
Unregistered guest
Posted From: 144.138.194.182
| | Posted on Sunday, 31 October, 2004 - 09:28 pm: | |
I havent heard (even a rumour) or read (even a snippet) about other makes of cars/trucks which had inherently weak Pitman arms which were prone to instant failure (at any point!) without "notice", the consequence being immeadiate loss of directional control. The potential for culpable liability beggars belief!. R-R have long suggested that hyd. hoses on Shadows be replaced at 96000 mls. (irrespective of their "apparent" condition) however I remain unaware of any requirement, explicit or implied, calling for periodic re-torqueing of Pitman arm retaining nuts in a manner/time frame similar to say,cylinder head bolts/nuts, the latter being a common requirement upon a variety of auto engines, past and present. If these recorded (and CONTINUING!) pitman arm failures were the result of poor maintenence or "neglect" (real or imagined) you can bet your booties that R-R would NOT (repeat N.O.T!!)coyly "offer" replacement/s with a visually more robust (thicker/enlarged) retaining "boss" area, on a free of charge basis. IF you complain and say your are related to Ralph Nader you will probably get one. Dont ask me how I "know" this.
(Message approved by david_gore) |
David Gore
Moderator
Username: david_gore
Post Number: 325
Registered: 4-2003
| | Posted on Monday, 01 November, 2004 - 06:13 pm: | |
Gentlemen and others,
This problem has finally dragged me out of "retirement" and my metallurgical curiosity has got the better of me so I am attempting to get hold of some cracked arms for inspection and/or [with the owner's permission] detailed examination to determine the mode of failure.
Watch this space for developments HOWEVER I suggest ALL Shadow owners should have their Pitman arms checked for cracking as soon as possible if you haven't already done so. The consequences of even one car having an undetected problem and the security of knowing your car is safe are enough justification for the cost of this inspection. |
Richard Treacy
Grand Master
Username: richard_treacy
Post Number: 411
Registered: 4-2003
| | Posted on Monday, 01 November, 2004 - 06:24 pm: | |
David,
I'll check whether I still have the cracked Pitman arm. If so, I'll have it posted to you.
Usually I throw useless bulky items away, but I may have kept this spectacular gem for posterity.
PS it may be a little spoiled. I tack welded the crack so I could at least manoevre the car gently into the garage while we awaited a spare. The first replacement I received was presumably for an earlier car and did not fit, so the car was out of action for two weeks until the correct one arrived.
RT. |
Patrick Lockyer.
Prolific User
Username: pat_lockyer
Post Number: 35
Registered: 9-2004
| | Posted on Tuesday, 02 November, 2004 - 12:03 am: | |
Robert Chapman.
Preventative Go to the route cause and somthing you don't always find in the factory schedule or manufactures bulletins.
Can only be learnt from years of expierence and comonsence, somthing i pass on when needed.
I hope that all folk take my advice seriously.
Crewe would even at this late stage of time do a recal if was a serious issue.
It is a known fact that there is a weekness by the fact of a modified arm.
Rest assured [AFTER THE HORSE HAS BOLTED]that after fitting the modified arm the other faults that have not been delt with will in a longer time
render problems on the taper.
Mabe RR have excepted that there is diferent stadards of workmanship carried out and of which they have no control. |
Robert Chapman
Prolific User
Username: shadow
Post Number: 99
Registered: 5-2003
| | Posted on Tuesday, 02 November, 2004 - 04:50 pm: | |
Pat,
How could you possibly expect anyone to take you or your advise seriously,when you make such ridiculous STATEMENTS as "the arms will not crack if you re-tension the nut every 2 years" and "if it was a serious issue".
What could be more serious that a total instant loss of steering I would like to know,OF COURSE ITS SERIOUS.
As for you passing on your "experience and commonsense",you must be having a laugh ,this must be a wind-up.
I have never read anything from you that remotely resembles or indicates either.
Do you think you are the godfather of the motor industry,what makes you think you are the only one with years of experience.
As for "different standards of workmanship"I bet R-R never in their wildest dreams(who would) thought there would be some nutter out there loosening and re-tightening the pitman arm nut over and over in order to stop it cracking?.
Do you write this stuff to offset the boredom of irrelevance or simply just a wind-up.
And I thought Jerome Beadle was good,you had Richard, John, and myself all going there, we all thought you were serious!What is this, have a laugh at the Australians week. |
Patrick Lockyer.
Prolific User
Username: pat_lockyer
Post Number: 39
Registered: 9-2004
| | Posted on Tuesday, 02 November, 2004 - 05:44 pm: | |
Robert.
Nothing like an alarmist posting from you yet again and we all know why that is.
can't grasp the underlying cause of the problems either.
I WILL REPEAT.
1. DYNAMIC WHEEL BALANCE.
2. BRAKE DISC DISTORTION.
3.TYRE RUN OUT AND FLAT SPOTS.
4.BUMP STEER BY INCORRECT SET UP ETC ON ROUGH ROADS.
All of the above will cause stress on the pitman arm,old type or new.
So you are saying do not bother with the stated faults or that they are of no concern to the issue.
I put it to you that your many arms found with cracks in them point directly to my above statement.
To clarify further to your failures please give the percentage of cars found with the cracks. |
Patrick Lockyer.
Prolific User
Username: pat_lockyer
Post Number: 40
Registered: 9-2004
| | Posted on Tuesday, 02 November, 2004 - 05:50 pm: | |
Robert.
I will let you work out why it is vital to deal with the nut excersize, you realy must use common sence on that. |
Robert Chapman
Prolific User
Username: shadow
Post Number: 100
Registered: 5-2003
| | Posted on Tuesday, 02 November, 2004 - 07:46 pm: | |
No no Pat, please stop it my sides are splitting.
A jokes a joke but we have tumbled you now,you took it to far with the pitman arm nut thing,that gave you away,it was just to silly to be true.
When I think back to all those other outrageous statemets you have made and ridiculous arguments you have put forward and all the time you were just winding us up.I should have known you could not be serious,your good for a laugh I will give you that.
Well you have had your laugh,I will not be taken in by anything you have to say from now on.
Have you heard the one about the monkey and the MOT tester they sent to the moon. |
Patrick Lockyer.
Prolific User
Username: pat_lockyer
Post Number: 41
Registered: 9-2004
| | Posted on Tuesday, 02 November, 2004 - 08:17 pm: | |
Robert it has been your manner and statements with alarmist posts and now you have realized how wrong you are and for all to see.
All you can do is show your true colours and try to laugh it off.
Sad on you. |
Robert Chapman
Grand Master
Username: shadow
Post Number: 101
Registered: 5-2003
| | Posted on Tuesday, 02 November, 2004 - 09:20 pm: | |
Pat,
I have told you,you have been sprung,you won't get me going any more,what a card you are.
I should have twigged when you came out with that "incorrect facts" thing, how did you keep a straight face whilst posting that? .
And the best one was the way you wrote your post's,making out you were drunk! BRILLIANT
Can I take it from this post you have heard the one about the MOT tester and the monkey then?
Say good night Pat, good night Pat. |
Patrick Lockyer.
Prolific User
Username: pat_lockyer
Post Number: 42
Registered: 9-2004
| | Posted on Tuesday, 02 November, 2004 - 11:11 pm: | |
Robert.Good night to you.
And now good morning to you.
I am sure i will now get you going to let us all have your program of registerd percentage failures so we all have some idea of the problem with the cars you have dealings wih of course you will find a great diference once you deal with the stated items above that i have provided you. |
John Dare
Unregistered guest
Posted From: 144.138.194.57
| | Posted on Tuesday, 02 November, 2004 - 07:47 pm: | |
No disrespect nor offence is intended toward our U.S cousins when I say that, following many visits to that great country, I have noted far more sub standard (neglected and/or abused) condition, Silver Shadows than here in Australia. I have of course, taken into account, the population difference in the course of those observations (during which time I HAVE seen some examples from good to very good, to spectacular!) and remain mindful of comments made by well known (and "R-R" AUTHORITIVE) Englishmen, who, upon visiting Australia, have remarked upon the GENERAL higher standard of cars to be found here. Perhaps it is because "our"(VERY expensive!)cars here are somewhat more respected, if not revered (and serviced/maintained accordingly!) that many have been EXPORTED, most notably, BACK to ENGLAND!.I will refrain from any comment on the "quality" of recent(previous 10 years) U.K Shadow imports (ex Luton or Peckham?) as frequently orchestrated by "fast buck" mechants in pursuit of a quick dollar. During my discussions in recent years with several U.S based R-R specialists regarding pitman arms, NONE have reported fractured arms in pre SS11 (LEFT drive) vehicles, despite the fact that many such cars appear to have been simply "driven", with token (if any) regard to service and maintenence. NO comments were made re the periodic re-torqueing of nuts; cyl.head/exh.manif.nuts excepted. With rates in excess of US$100 per hour we may begin to understand how that situation may have evolved over the years. Now, the $64K question IS.. Why is there no (or IF any, then virtually insignifigant) failure in LHD pitman arms which are PRESUMABLY (point open to debate) a "mirror" image (reverse orientation) of the "sister" RHD arm. I have already put this tantalizing question to our very own "world authority/expert", but sadly, as with most self appointed experts I have encountered upon the tortuous highway of life, the silence has been deafening. Perhaps the proposed metallurgical investigation (by a suitably qualified PROFESSIONAL!) might serve to provide the elusive answer. And NO.. its NOT the perceived "poor" condition of Australian roads, since the majority of R-Rs in this country, proceed quiety upon roads generally similar to those found in the USA. And of course, do so without a dreadful caravan in tow.
I would be VERY VERY appreciative if our overseas contributors could confirm that LHD Shadows have not experienced this problem or if the problem was confined to the original arms only. Thanks in anticipation David
(Message edited by david_gore on November 03, 2004)
(Message approved by david_gore) |
John Dare
Unregistered guest
Posted From: 144.138.194.114
| | Posted on Tuesday, 02 November, 2004 - 07:58 am: | |
I find the post of Nov.2nd (P.Lockyer) both confusing and contradictory. Although it is conceded that there was/is a weakness in the original design (hence the factory issue of a stronger arm)it is implied that, as there was no "official" (read EMBARRASSING!) recall, the issue (instant steering failure!) is NOT a SERIOUS issue. Then the poster optimistically declares his "hope" that we will take this (his!) "advice" seriously?. He goes on to suggest that even after fitment of the stronger, R-R modified arm, problems may still recur on the taper unless "other"(?)faults are addressed. I know of MANY cars (my own included) which have had the modified arm fitted and NONE of them have failed nor have they required "special" attention ( periodic re-torqueing) nor have their front suspension/steering components needed any more than normal basic servicing of the kind routinely performed by a first year apprentice or even a weekend D.I.Yer. If the poster has a recurring problem with his own taper, then perhaps further inspection is warranted to identify the unfortunate cause/s thereof.
(Message approved by david_gore) |
David Gore
Moderator
Username: david_gore
Post Number: 326
Registered: 4-2003
| | Posted on Wednesday, 03 November, 2004 - 08:56 am: | |
Hi Richard,
Sorry for delay in responding to your post above as I have been away - thanks for your offer however the tack welding "get-you-home-safely" repair will have destroyed the evidence I will be looking for to determine the cause of the cracking - I am not going to pre-empt this investigation however the are at least two plausible explanations for the problem; one is obviously fatigue, the other is ductile/brittle transition temperature associated with other service factors.
I am going to need all the help I can get on this problem from owners of affected cars with information on the location, use, driving habits, climatic conditions etc once the possible causes are identified. For example, Robert has mentioned recent failures in Melbourne yet I am not aware of any failures in Sydney [I have yet to check this out more thoroughly].
MY MAJOR CONCERN IS THE REPORTED FAILURE OF THE MODIFIED ARMS NOT THE ORIGINAL ARMS. |
Richard Treacy
Grand Master
Username: richard_treacy
Post Number: 414
Registered: 4-2003
| | Posted on Wednesday, 03 November, 2004 - 05:43 pm: | |
David,
From a selfish point of view, I too am more interested now in the reliability of the new type of Pitman arm as, like John's, ours has been replaced.
On location, our car has spent its years roughly half-half Sydney and Canberra. You could call it a Sydney car. It was delivered new in Sydney by York Motors and always serviced by them until I got my hands on it around 1985 when we considered it old enough for DIY. Always garaged, the temperatures have been mild with the exception of trips to the Snowy Mountains or the odd frosty morning outside. Mind you, it gets pretty hot down at the steering box when driving.
When I ordered the new part, the Sydney agent didn't need to look up the part numbers: Tom was rather familiar with this failure. That suggests that there have been rather a few failures in Sydney. Do you think that a few Kelvins temperature difference between cities would make much of a difference ?
I'll hold off on sending you the Pitman arm. I'm sure that Robert Chapman can provide what is most useful from his collection of trophies. As he has done a few and probably carries spares, he probably never needed to tack weld one to manoevre a car into a corner waiting for spares.
RT. |
Phil Sproston
Unregistered guest
Posted From: 203.206.48.94
| | Posted on Wednesday, 03 November, 2004 - 08:48 pm: | |
Pat, re. your post on 2-11-04, on your list you missed mentioning the Steering idler box. If it isn't filled with oil it can cause problems from the road vibration, which affects the Pitman arm. In almost every idler box I have checked there has been little to no oil remaining.
(Message approved by david_gore) |
Patrick Lockyer.
Prolific User
Username: pat_lockyer
Post Number: 43
Registered: 9-2004
| | Posted on Thursday, 04 November, 2004 - 11:47 pm: | |
Phil,spot on i had forgot that one and maybe some other points as i was rather quick to reply on the alarmist posting. |
Robert Chapman
Grand Master
Username: shadow
Post Number: 102
Registered: 5-2003
| | Posted on Friday, 05 November, 2004 - 10:56 am: | |
Phil.
Are you saying that an ineffective steering damper will CAUSE the pitman arm to break?
Or are you saying an ineffective steering damper will add extra stress to an already CRACKED pitman arm, as would all shock loads feed back into the steering.
|
Patrick Lockyer.
Prolific User
Username: pat_lockyer
Post Number: 44
Registered: 9-2004
| | Posted on Friday, 05 November, 2004 - 05:32 pm: | |
Robert Chapman.
still cannot understand, except the route causes and correct them on your cars.
The cracks you are finding relate direcly to your failure to except the above.
What is your percentage of failures we are all still waiting to help you on this matter. |
John Dare
Unregistered guest
Posted From: 144.138.194.153
| | Posted on Friday, 05 November, 2004 - 08:14 am: | |
Some of the many cars which I have owned in the past, including some in my current possession, have steering "dampers" and some do not. Those without such dampers have NOT suffered abnormal tyre wear let alone ANY failure of a steering related component, especially not a Pitman arm. For obvious reasons such CRITICAL components are USUALLY "overdesigned" in the FIRST instance, and then attached to the steering box shaft in a "fail safe" manner; splined/tapered/securing nut etc. The irrefutable record CLEARLY indicates that the original Shadow pitman arms were far from "OVERdesigned", hence the later issue of the redesigned, stronger unit. I am unaware of any failures of the later modified type ,irrespective of whether or not the car/s were (or are) fitted with idler/damper boxes.
(Message approved by david_gore) |
Patrick Lockyer.
Prolific User
Username: pat_lockyer
Post Number: 52
Registered: 9-2004
| | Posted on Saturday, 13 November, 2004 - 06:17 am: | |
No confirmed breakages of arms i thought there would have been according to the alarmist posting,but alas it seems that the many cars apart from the Melbourne Specialist are maintained to a satisfactory standard with the above points delt with.
|
John Dare
Unregistered guest
Posted From: 144.138.194.195
| | Posted on Saturday, 13 November, 2004 - 07:39 am: | |
Patrick. If you ever do favour us with your presence and worldy knowledge, you will discover that there are places and locations in Australia, OTHER than Melbourne (SYDNEY for example) where Shadow Pitman arms have failed. Different owners,different(traffic)environmemt/operating regimes and(obviously)different service points and facilities. How say you now?
(Message approved by david_gore) |
Patrick Lockyer.
Prolific User
Username: pat_lockyer
Post Number: 54
Registered: 9-2004
| | Posted on Saturday, 13 November, 2004 - 09:10 am: | |
J.G.Dare.
Of confirmed horrible letter fame.
As others and i have stated before you are no engineer,just a professional bore with words. |
John Dare
Unregistered guest
Posted From: 144.138.194.234
| | Posted on Saturday, 13 November, 2004 - 09:52 am: | |
Thank you Patrick. Thats WHY we NEED you here (in person) to SHOW (rather than simply "tell")us mere mortals HOW to perform various "R-R" repair/maintenence procedures. All tools, equipment and parts can be made available for the grand event which I expect will be a most memorable experience not easily forgotten. All you need do is let us know when you are coming. Any time soon?
(Message approved by david_gore) |
Patrick Lockyer.
Prolific User
Username: pat_lockyer
Post Number: 60
Registered: 9-2004
| | Posted on Tuesday, 16 November, 2004 - 05:50 am: | |
J.G.Dare.
Of confirmed horrible letter fame.
More of your Rubbish.
|
John Dare
Unregistered guest
Posted From: 144.138.194.249
| | Posted on Tuesday, 16 November, 2004 - 10:53 am: | |
It has been asserted by the worldy and wise, that the widely documented failure of Shadow (Series 1) pitman arms is attributable (in some way) to neglect, poor, or sub standard "maintenence" etc. I wonder why there has been no recorded (frequent) failure of say, Mark V1/"R"type/Dawn or "S" series cars Pitman arms, especially given that those cars are so much OLDER, have had many owners and therefore widely varying service personel attending to them, neither of whom may have regularly observed and maintained the highest service/maintenence standards.
(Message approved by david_gore) |
Richard Treacy
Grand Master
Username: richard_treacy
Post Number: 436
Registered: 4-2003
| | Posted on Wednesday, 17 November, 2004 - 09:53 am: | |
John,
At the risk of rebuke, you know my views. A Pitman arm, or its side arm lever cousin on a Mk VI, has no excuse whatsoever for any sort of failure ever. Nor does a final drive or rear suspension crossmember.
The fact that RHD Shadow Pitman arms and all Shadow final drive crossmembers fall off at random is astonishing and has nothing to do with maintenance, abuse or bumps in the night.
I don't care if they mostly all break at just 10 km/h, they are still critical safety-related failures. It is not a cost issue: we all want to stop the risk of catastrophe to ourselves and our families.
My yet-again leaky steering rack, after replacing it 9 months ago, will cost me a grand or so too, but at least the damage so far is just a letter from the police complaining about oil stains on the carpark. Fines may follow. With standard maintenance, I can check the steering fluid for a very slow leak, but not metal fatigue.
RT. |
Patrick Lockyer.
Prolific User
Username: pat_lockyer
Post Number: 64
Registered: 9-2004
| | Posted on Wednesday, 17 November, 2004 - 05:42 pm: | |
Richard,i may be able to hopefuly help on the leaking rack.
Is there a topic on racks some where as i think we ought to keep this one to the pitman arm.
In haste PL. |
Robert Chapman
Grand Master
Username: shadow
Post Number: 105
Registered: 5-2003
| | Posted on Wednesday, 17 November, 2004 - 07:32 pm: | |
Richard,
It would seem that you also, have failed to "grasp the route cause" of these failures (according to pat).
But I am sure you are very pleased and greatful that help is on the way regarding your leaking rack,well I think thats what he said.
|
Robert Chapman
Grand Master
Username: shadow
Post Number: 106
Registered: 5-2003
| | Posted on Wednesday, 17 November, 2004 - 08:04 pm: | |
Richard ,
At the risk of being called alarmist,what is your opinion on changing the two centre rack bolts,or at least inspecting very closely for necking,when removing or refitting racks.
I have found quite often that they have been over tightened(not using torque wrench)and are visibly stretched in the threads.
I would be interested,doe's your rack leak from the top pinion seal or ram?. |
Richard Treacy
Grand Master
Username: richard_treacy
Post Number: 437
Registered: 4-2003
| | Posted on Wednesday, 17 November, 2004 - 09:27 pm: | |
Robert,
I'll switch the rack topic to Silver Spirit etc. |
John Dare
Unregistered guest
Posted From: 144.138.194.241
| | Posted on Wednesday, 17 November, 2004 - 10:40 am: | |
Thank you Richard. I need to clarify beyond any doubt that it was NOT I (nor you, as I recall) who had vehemently suggested that certain Shadow problems (particularly Series 1 pitman arm failures)were the result of operator abuse, sub standard or questionable maintenence procedures such as "failing" to re-torque pitman arm retaining nuts at periodic intervals. If either of those factors were proven to be causative, then not unreasonably, one would have expected similar Pitman arm failures (incl. frequency of)in earlier "R-R/B" vehicles, due to their (older) age, during which time they would have been exposed to different owners AND a wide variety of service/maintenence regimes. To date, I remain unaware of any such failures, and as you further indicate, none are expected. Nor should they be.
(Message approved by david_gore) |
David Gore
Moderator
Username: david_gore
Post Number: 328
Registered: 4-2003
| | Posted on Thursday, 18 November, 2004 - 10:09 am: | |
Hi Richard,
re testing Pitman arms; I suspect you would be aware that you can dye-penetrant test [either visible dye or UV fluorescer] these for incipient cracking however it is essential to remove them from the vehicle and thoroughly degrease/clean the arm boss before testing.
If you would like more information; please contact me direct. |
John Dare
Unregistered guest
Posted From: 144.138.194.15
| | Posted on Monday, 22 November, 2004 - 01:35 pm: | |
During the discussion under this thread, it was implied that Shadow 1 Pitman arms had failed due (in part)to "improper maintenence"; in particular, the failure to periodically re-torque the Pitman arm retaining nut. I am unaware of this practice and have NEVER heard, let alone READ (in ANY publication/s; mnfrs. or independent authority)of this service requirement. I suspect that is due, in part,to the potential,however remote, for auto. servicemen (somewhere) to either under tighten, or worse, OVERtighten the nut, the latter tending to drive the pitman arm "hub" further onto the tapered steering shaft spline with inevitable consequences. That observation ASIDE, I ask WHY is it that IF the suggested procedure (re-torqueing) has been "ignored", thereby contributing to Shadow 1 arm failures, WHY is it that Mk6/Dawn/R-type and "S" series pitman arms have not ALSO failed, given that, to my knowledge, such cars have NOT (according to R-R) required periodic re-torqueing, NOR have owners done so of their own volition in deference to pre-emptive and of course, "correct" maintenence.
(Message approved by david_gore) |
Robert Chapman
Grand Master
Username: shadow
Post Number: 116
Registered: 5-2003
| | Posted on Monday, 22 November, 2004 - 09:31 pm: | |
Hi David,
It is the dye penetrant method we are using on all cars passing through the workshop, as I have told Richard we have changed 5 in the last 3 years(not including the latest 3).
Three were detected cracked by testing on car and 2 were cars brought in(with arms completely broken) previously unknown to us.
We test them in position and if in any doubt removed,both free and bolted up to a dummy shaft.
I am sure there has never been any failure of the replacement arms,and when the new type arm is seen,it is obvious why.
Would it be possible to post the photo I sent showing the two different arms. |
Richard Treacy
Grand Master
Username: richard_treacy
Post Number: 451
Registered: 4-2003
| | Posted on Monday, 22 November, 2004 - 10:29 pm: | |
Robert,
I am relieved to hear that you cite no cases of failed new-type Pitman arms.
Posting the pictures would be very useful. Viewers can then identify whether their Pitman arm is a new safer type or not. The new type is indeed quite noticeably different. We have spent the cash on a new one already, so cannor benefit.
I would go so far as to urge all owners with the original type to replace it immediately test or not as it's clearly a time bomb. If people pool together, pressure could be brought on Crewe to give a very reasonable price for a large quantity. It's no use pretending that this issue will fade away, so why not bite the bullet ? The labour involved is not at all great, and an early replacement will save time, cost and convenience, let alone the safety issue.
When ours broke some years ago, my father was doing a U-Turn which became almost a loop. The shock of losing control can lead to any imaginable reaction. Thank goodness there was no traffic. Usually on doing a U-Turn you hurry off to avoid the following traffic. Even if a U-Turn is at just 5 km/h a serious accident can easily result as the traffic collides with your car.
Please, no one tell me this is not a safety matter because failure is almost always at low speed. I would not enjoy losing my steering at just 10km/h on a hairpin bend, and plunging down a cliff. |
Richard Treacy
Grand Master
Username: richard_treacy
Post Number: 452
Registered: 4-2003
| | Posted on Monday, 22 November, 2004 - 10:37 pm: | |
For David Gore:
I have enquired about LHD Pitman arms in Europe and the US, and have no report of a Pitman arm failure on a LHD car. I dare not ask Crewe though. The main dealer here in Zürich has confirmed only RHD failures, and quite a few at that.
That doesn't mean that they don't fail, but it does seem to be a RHD thing. Maybe General Motors / Saginaw put too little effort into the conversion of their overall design to RHD.
Next time I'm near a LHD Shadow I'll poke the camera underneath and post the picture.
RT. |
David Gore
Moderator
Username: david_gore
Post Number: 331
Registered: 4-2003
| | Posted on Tuesday, 23 November, 2004 - 09:34 am: | |
Hi Everyone,
Have attached photo below and thanks to Robert for sharing this with us - note the significant increase in the thickness of the boss. My thoughts on the failure are as below:-
1. The undisputed fact that failures have only occurred on RHD vehicles suggest the cause of the problem may not be under-design but related to stress loadings generated by the linkages in the RHD system. If there was an inherent design fault; failures should have occurred on both LHD and RHD vehicles.
2. The location of what appears to be a classic reverse-cycle fatigue crack on one shoulder of the boss only indicates non-uniform stress loadings from linkage movements/suspension loadings - what would be interesting would be to know whether the stress is coming from LH or RH turns. If the loadings were equal from each type of turn; I would have expected cracking to be evident on each shoulder of the boss with ultimate failure from the side subject to the greatest number of heavily loaded turns [eg turning downhill into a home driveway where all the loads are on the outside wheel].
3. With due respect to Pat's experience and knowledge; I am yet to be convinced that this type of failure can be prevented by regular retorqueing of the arm retaining nut - this practice is desirable to prevent premature wear of the splines but I can see no metallurgical benefit from this practice which would neutralise the cause of the fatigue cracks observed. The usual solution to fatigue cracks of this nature is to reduce the generation of tensile stresses at the metal surface and to eliminate any stress concentrators such as notches, abrupt changes in section and/or machining marks. Tensile stresses may be reduced by increasing the metal thickness as evident in the modified arm, by inducing compressive stresses in the surface layers by case/flame hardening or by shot peening. Of course, the best solution is to look at the overall design of the system to reduce overall stress loadings wherever possible.
4. With regard to Richard's comment on conversion of the Saginaw unit to RHD - my view is that the unit would have been designed to withstand equal loadings from either extremity of component movement. the one-sided incidence of this failure suggests very emphatically to me that the problem is related to the design/action of the RHD linkages.
Hope this is of interest and will generate some discussion from our practical contributors who have actually worked on this problem - I have not had this experience and qualify my comments accordingly.
Robert's photo of cracked original arm and factory modified replacement
|
David Gore
Moderator
Username: david_gore
Post Number: 332
Registered: 4-2003
| | Posted on Tuesday, 23 November, 2004 - 10:18 am: | |
Further to the above photo; have enlarged cracked arm so failure is easier to see for your benefit.
Location of Crack
Close-up of Crack
|
Patrick Lockyer.
Prolific User
Username: pat_lockyer
Post Number: 90
Registered: 9-2004
| | Posted on Tuesday, 23 November, 2004 - 05:38 pm: | |
Thank you Robert for the letting us have a look at the pictures of the pitman arm and David for his findings.
I agree also it is caused by load stress Fatigue.
However as i have stated from the start brought about by the loadings of the steering through the above failings of stated points not being carried out.
As the for the torqueing of the nut excersize i will let you all work on that for the time being.
As i have said there is a weakness in the arm but only brought about by other underlying faults.
I will also tell of other sudden failings with the car and cars in general but only when it is brought up in a topic as i do not want appear an alarmist.
|
Robert Chapman
Grand Master
Username: shadow
Post Number: 117
Registered: 5-2003
| | Posted on Tuesday, 23 November, 2004 - 09:20 pm: | |
Hi Richard,
In answer to your post of 22/11 /04,I agree with your idea of Crewe supplying the arms at a much more reasonable price if not free, in the light of the obvious fault in this part.
And the ideal situation would be to replace them all before anymore fail.
In the mean time I shall carry on with the crack testing and if by doing so and bringing the fault to the attention of the owners I am labelled ALARMIST so be it .
I will be happy to bear that cross as I have a professional duty of care responsibility. |
Patrick Lockyer.
Prolific User
Username: pat_lockyer
Post Number: 92
Registered: 9-2004
| | Posted on Wednesday, 24 November, 2004 - 05:22 am: | |
David have had time to take a closer look at the above enlarged photo.
I am more alarmed than ever as it has confirmed my above statements.
The picture not only shows the fracture but the cause of it.
The movment on the splines and over a long period
somthing that would be detected in the vehicle servicing maintenence checks before it ever got in that state.
As i have said and i am most surprised that the torque nut excersise by other folk has not been excepted and taken up with a cunning but simple checking procedure.
Regarding the fitment of a modified shaft,i cannot believe that there has been no mention of the damaged rocking shaft splines or do they not wear.
most of the route causes i have stated above in previous posts.
Regarding the LHD RHD shafts are they both the same part numbers.
|
Richard Treacy
Grand Master
Username: richard_treacy
Post Number: 453
Registered: 4-2003
| | Posted on Wednesday, 24 November, 2004 - 06:11 am: | |
The LHD and RHD side arm levers (Pitman Arms) are not the same.
For example, late chassis SSI have UR18370 (RHD and UR18371 (LHD) originally, secretely superseded by something like UR22990 and UR22991.
Under a failure condition, the weak side is clearly the arm/lever itself, and after checking this in as many cases as possible, the steering box output spline has never known to be worn or damaged after a sadly normal Pitman arm failure. The failed one in David's picture has probably been lying around and corroded a bit as well.
The substantially beefed-up nature of the revised Pitman arms is encouraging.
RT. |
Patrick Lockyer.
Prolific User
Username: pat_lockyer
Post Number: 94
Registered: 9-2004
| | Posted on Wednesday, 24 November, 2004 - 06:20 am: | |
Crums Richard that was quick thanks.
However it has opened another thought and closed one.
Back to the Glenfiddich! |
David Gore
Moderator
Username: david_gore
Post Number: 333
Registered: 4-2003
| | Posted on Wednesday, 24 November, 2004 - 08:20 am: | |
Pat & Richard,
Thanks for your observations - further to my original comments and WITHOUT the benefit of examining the cracked arm; I am reasonably confident the fatigue crack has initiated on the surface of the boss shoulder and progressed inwards towards the splines. You will note there is a "crease" mark from the forging process on the shoulder and my suspicions are that this has acted as a stress concentrator to initiate the crack. For this reason; I still have to be convinced that retention practice will definitely control this mode of failure Pat, please contact me direct if you wish to discuss this in more detail with me privately
WHAT STILL PERPLEXES ME IS THE FACT THAT THIS FAILURE ONLY OCCURS ON RHD VEHICLES. |
John Dare
Unregistered guest
Posted From: 144.138.194.56
| | Posted on Tuesday, 23 November, 2004 - 11:12 am: | |
At last what appears to be the definitive answer!. And someone once said "SIZE doesnt matter"?. LOOK at the DIFFERENCE in boss/hub size DIAMETER of the two Pitman arms as clearly depicted!. I extend my appreciation, especially to those who contributed to this vexed topic, doing so at what was clearly a professional level. At least the more astute among us may now relax, knowing that we dont have to adjust or otherwise interfere with our nuts, even though some may,for whatever dubious reason/s, continue to do so.
(Message approved by david_gore) |
Patrick Lockyer.
Grand Master
Username: pat_lockyer
Post Number: 101
Registered: 9-2004
| | Posted on Thursday, 25 November, 2004 - 01:40 pm: | |
J.G.Dare.
More rambling rubbish.
(Message edited by david_gore on November 25, 2004) |
John Dickinson
Frequent User
Username: au2018
Post Number: 14
Registered: 11-2003
| | Posted on Saturday, 27 November, 2004 - 10:19 am: | |
Hi to all,
Being a recent convert to the world of motor cars (after motorcycle ownership for most of my adult life) I find technical discussion such as this thread quite fascinating viz. Pitman Arm Failure.
Could someone please help me here? When discussing a Pitman Arm which component in the Silver Shadow steering mechanism are you actually referring to? The R-R CD manuals indicate the cross beam member, idler lever, pendulum lever and track rods.
Thanks for any help. |
Richard Treacy
Grand Master
Username: richard_treacy
Post Number: 458
Registered: 4-2003
| | Posted on Saturday, 27 November, 2004 - 08:31 pm: | |
Pitman Arm is US/Oz for pendulum lever, mate. |
Bill Coburn
Grand Master
Username: bill_coburn
Post Number: 282
Registered: 4-2003
| | Posted on Saturday, 27 November, 2004 - 11:21 pm: | |
an interesting question John. I have often wondered who was Pitman other than the man who invented the most used shorthand. But presumably he did something for the 'pendulum lever' and attached his name to it. The 'pendulum arm' descriptive is simple in that the original manual steering boxes had horizontal output shafts on which an arm was attached which swung forward and backward pushing a 'drag link' that in turn swivelled the wheels. Poor Mr Pitman - lost in time but he would probably be horrified that his creation was so poorly executed my the manufacturers of the 'Best Car in the World'! |
Richard Treacy
Grand Master
Username: richard_treacy
Post Number: 459
Registered: 4-2003
| | Posted on Saturday, 27 November, 2004 - 11:43 pm: | |
Bill,
On Mk VI etc it is named Pendulum Lever in the literature, with the fore-aft drag link ("side steering tube") as you describe.
Other names are side arm lever, drop arm lever, and pendulum arm as you point out.
Trust we Aussies to make up our own component names. I challenge you to order a circlip in German though. Last week I had to buy some circlip pliers in French. That was a challenge I can assure you. |
Richard Treacy
Grand Master
Username: richard_treacy
Post Number: 460
Registered: 4-2003
| | Posted on Sunday, 28 November, 2004 - 03:27 am: | |
Just a titbit of information.
All Silver Shadows have the same idler lever, although of course LHD and RHD are mirrored, as are the Pitman arms. The idler damper was virtually unchanged through the series too. This is despite the deletion of the subframe Panhard rod along the way (I think that diasppeared when the compliant suspension came along), and the front levelling disappearing at Chassis 12586.
All idler arms:
RHD: UR14702
LHD: UR14703
The Pitman arm changed when the last change to the steering box was introduced at chassis 11215. There were quite a few cars with the earlier box produced after 11215, presumably a light-steering option.
Pitman arm number until chassis 11214:
RHD: UR13344
LHD: UR13345
From chassis 11215, most were
RHD: UR17106
LHD: UR17105
There is no apparent correlation between compliant suspension and Pitman arm failures it seems: our T has pre-compliant suspension and had the later Pitman arm until it broke, and I know of several compliant-suspension cars which have suffered failures too.
It would be interesting to know if any earlier UR13344 Pitman arms have failed. Also, perhaps Robert could let us know the present replacement part number, and whether the UR13344 and UR17106 have a common replacement.
RT. |
Patrick Lockyer.
Grand Master
Username: pat_lockyer
Post Number: 104
Registered: 9-2004
| | Posted on Sunday, 28 November, 2004 - 03:45 am: | |
Ok so here "Uk" we call it all three,but most common drop arm.
Anyway back to the failings of only Rhd vehicles and in my opinion brought about by the loading of the steering brought about by the stated above on the early shaft.
Now why just Rhd after the 10 year design and all testing before the launch of the car,surely if it
was a problem it would have shown up or would it.
Could the later deletion of the Panhard rod fitted to the sub frame of the early car be the cause.
This clever little chap was used to stabilise the
the front sub frame that as we know is mounted on flexible mounts to stop vibrations [noise],dificult due to the low frequencies as the whole subframe will have a resonant at one of its natural mounting frequencies confirmed by by slight shake under controlled testing.
Now why rare failings of rhd cars,i believe it is caused by "Directional torque" within the subframe,with the engine and gearbox mounted within.
Was that the clever design engineers reason of the panhard rod,if so would be confirmed by no failings of early cars arms.
They sure would have done a recall if there was!
If it is so then the modified arm will not break but will fail on the splines over a longer period of time,more so with the the above service maintenance problems pressent and the nut torque excersise not carried out. |
John Dickinson
Frequent User
Username: au2018
Post Number: 15
Registered: 11-2003
| | Posted on Sunday, 28 November, 2004 - 10:26 am: | |
Thank you Messrs Treacy and Coburn. I appreciate your assistance in explaining the diverse nomenclature of the humble Pitman arm. |
John Dare
Unregistered guest
Posted From: 144.139.15.141
| | Posted on Saturday, 27 November, 2004 - 04:00 pm: | |
Thank you John. In the "R-R" S/Shadow (Series ONE!) W/shop manual/parts book, it is referred to as the Pendulum lever. Like almost EVERY vehicle on the road (commercial or passenger type) such arms, variously referred to as Drop,Pitman or Steering arms, are fitted (for obvious reasons) by a "double indemnity/fail-safe" method of being mounted on a tapered spline, thereafter secured with a nut torqued to a very high tension. Said nut therefore (usually) has few threads, being intended to be torqued (upon initial installation (at factory and/or after removal/replacement of steering box) AND THEN LEFT ALONE. Such nuts are NOT "multiple cycle" nuts to be loosened and tightened like simple "Marmite" lids/Scottish Malt caps or other commonly found screw/threaded type fasteners.
(Message approved by david_gore) |
Patrick Lockyer.
Grand Master
Username: pat_lockyer
Post Number: 112
Registered: 9-2004
| | Posted on Tuesday, 30 November, 2004 - 05:45 am: | |
J.G.Dare.
Read the posting above, EVERY TWO YEARS.
and then a proceedure that you and others have failed to work out.
(Message edited by david_gore on November 30, 2004) |
John Dare
Unregistered guest
Posted From: 144.138.194.90
| | Posted on Tuesday, 30 November, 2004 - 07:34 am: | |
I have yet to read in ANY automotive book or mnfrs. workshop publication, ANY reference (express or implied) regarding the "two year" interval or indeed ANY interval, requiring the re-torqueing of Pitman arm retaining nuts. Perhaps those who continue to stridently advance this notion could quote a supporting reference from some (ANY) recognized auto. text book which they read during their studies whilst in pursuit of their automotive related qualifications. At that time it would be opportune for them to finally declare the precise nature of said qualifications, in order that some credibility might be established to support that which they continue to espouse.
(Message approved by david_gore) |
Patrick Lockyer.
Grand Master
Username: pat_lockyer
Post Number: 122
Registered: 9-2004
| | Posted on Wednesday, 01 December, 2004 - 07:19 am: | |
J.G.Dare.
As i have said before,years of practicle experience not always learnt from a book.
As you cannot except that,i have no satisfaction to tell you and then be ridiculed by you.
Regarding the the posting on the 28th it would be interesting if there was some response to maybe an interesting subject.
PITMAN ARM FAILURE.
|
John Dare
Unregistered guest
Posted From: 144.138.194.6
| | Posted on Wednesday, 01 December, 2004 - 11:37 am: | |
Thank you Patrick, for yours of 1/12 (8-19am) where you appear to imply that your technical knowledge has been aquired by practical experience. Would you please advise details of your experience and qualifications.
(Message edited by david_gore on December 01, 2004)
(Message approved by david_gore) |
Patrick Lockyer.
Grand Master
Username: pat_lockyer
Post Number: 126
Registered: 9-2004
| | Posted on Wednesday, 01 December, 2004 - 05:47 pm: | |
Pitman Arm failings is the topic here.
Are we now to have a qualifications topic for all who use this forum!
I will be pleased to do so if that is the case as i do not need to SWANK with mine at present. |
John Dare
Unregistered guest
Posted From: 144.138.194.131
| | Posted on Wednesday, 01 December, 2004 - 07:02 pm: | |
Thank you Patrick. Yes, the topic is S/Shadow (series 1) Pitman arms;failure of. From the outset you have vigorously espoused the theory that said failure is the result of lack of maintenence, primarily, the failure to periodically re-torque the pitman arm retaining nut. You continued assertions in that regard (incl.ref.to other alleged causes) blatantly defy compelling evidence from qualified professional automotive engineers,technicians and even metallurgists!. Repetitious comment deleted. For the record; the metallurgist is keeping an open mind on this as there are possible maintenance-related causes for the problem and I have not seen any evidence so far to eliminate this possibility
(Message edited by david_gore on December 02, 2004)
(Message approved by david_gore) |
whunter
Grand Master
Username: whunter
Post Number: 111
Registered: 10-2003
| | Posted on Thursday, 02 December, 2004 - 12:52 pm: | |
I should like to know at least some of your credentials, since you are giving advice on safety issues, steering and hydraulic system = brakes.
We make no issue of skill level.
However; people have a right to know at least some credentials possessed by the person telling them to spend money on this or that repair.
Evasion is not acceptable...
If you are a retired Rolls-Royce / Bentley engineer or technician, possibly a research person from CREWE, a mechanic working at the corner garage, even an owner who works on their own cars.
If privacy is a concern, send the information to David Gore, he may winnow it down to a brief statement and e-mail the registered forum members.
Please make a clean breast of it; and close the question…
Have a wonderful day. |
William H. Trovinger II
Grand Master
Username: bill_trovinger
Post Number: 176
Registered: 8-2003
| | Posted on Thursday, 02 December, 2004 - 02:35 pm: | |
Whunter;
I do not know if I agree with you or not. As showing ones credentials has never been a prerequisite to posting, let alone as you state “a right to know”. I think each owner can (and should) take comments made by other (whether on this site or any of the other sites) with at least a grain of salt, unless that person is forthright with their background.
However, if one where wishing to push this issue than I believe you should also include Mr. Dare as I do not recall a posting where he as spelled out his qualification either. After all fair is fair and Mr. Dare has made many a claims on this and other forums.
With that said and in light of the seriousness of this issue (and others) I would like to ask all contributors to keep comments to the issue of the thread and leave personalities out of the debate.
Best regards,
Bill
Moderator's Comment:
Thank you Bill as I am sure your views match those of the "silent majority" who visit this site. I have also addressed this problem in my comments to today's posts in the topic "Static V Dynamic Compression".
All posts regardless of whether they come from registered users or guests are now being edited without fear or favour to remove extraneous comments that are not relevant to the topic under discussion.
(Message edited by david_gore on December 02, 2004) |
John Dare
Unregistered guest
Posted From: 144.138.194.200
| | Posted on Thursday, 02 December, 2004 - 12:17 pm: | |
Thank you D.Gore;your addendum of 2/12. On 30/10, P.Locker opened this particular thread and implied in his opening para.that poor maintenence was a causative factor;at para.1 specifically referring to the pitman arm retaining nut, suggesting that it should be, "released and retorqued every couple(?) of years or so to 200lb.ft"(sic). On 2/12, you indicated that you are keeping an open mind on maintenence related causes and that you have not seen any evidence so far to eliminate this possibility. Apart from evidence previously supplied from qualified and long experienced engineers and auto. technicians, kindly allow me to sumbit in evidence (hard copy available) a response received this day from a U.S based MANUFACTURER of Pitman Arms AND retaning Nut "kits" (washer/nut/pin etc.) who supply (OEM) major auto mnfrs.including that vehicle immortalized by a state Governor who has a large desk in Sacramento. The response unequivocally addresses the PRINCIPAL issue so tirelessly (AND authoritively) advanced to date, and I quote verbatim; "I have read the military maintenence manuals for many vehicles and have never heard of this being on a maintenence list for any reason". He added, "I would recommend against this retorquing procedure. At best it helps nothing and at worst it will cause wear and damage to the parts". I have nothing further (Well,not until additional and AUTHORITIVE supporting evidence is received,receipt of which is pending at this time)
Moderator's Comment:
John, in relation to my comment of today relating to an open mind; I was not specifically referring to the Pitman arm retaining nut but to other maintenance practices/neglect that could be contributing to the fact that failure has only occurred on RHD vehicles. A number of possible causes have been suggested to me privately and these will be assessed from a metallurgical perspective in the light of any information that becomes available.
(Message edited by david_gore on December 02, 2004)
(Message approved by david_gore) |
John Dare
Unregistered guest
Posted From: 144.138.194.14
| | Posted on Thursday, 02 December, 2004 - 08:51 pm: | |
Bill Trovinger. Thank you for your recent response in reply to your compatriot W.Hunter, wherein you suggest that contributors (to forums) are not obliged to reveal their qualifications, let alone assume a "right to know". As I recall, it was YOUR goodself who very much suggested YOUR "right to KNOW" the details of the analysis of "363" fluid, being an analysis, sought by, paid for, and held by me. It was not available to you then, nor is it ever likely to be, despite your moral posturings (at the time) about the "obligations" etc.,of "helping" fellow "R-R" owners etc. You are correct in that I have not volunteered my "qualifications" nor do I feel obliged to do so.
I did raise, on your fine U.S forum (as I did on this forum) the subject of "GM" engine conversions whereby I was attacked by all and sundry from Anchorage to Key West, almost expecting a dark suit to quietly arrive from Langley. My most memorable opponent was Douglas R, for whom I hold sincere respect, given his extensive knowledge, and he likewise, was gracious enough to concede (at the conclusion of "hostilities") that I "argued my point well" . As you may observe, I survived a phalanx of fire from your countrymen, recalling that only ONE (Mollich) or perhaps two (?) DARED to volunteer any supportive commentary, perhaps being ruefully aware that "GM"conversions (upon "R-R"s) were indeed, FIRST PERFORMED IN THE USA!.
Moderator's Comment:
John, after much soul searching I have had to delete your questions relating to the US forum as these are internal policy matters relating to moderators and their duties which are determined and applied by the US RROC at their absolute discretion.
(Message edited by david_gore on December 03, 2004)
(Message approved by david_gore) |
whunter
Grand Master
Username: whunter
Post Number: 112
Registered: 10-2003
| | Posted on Friday, 03 December, 2004 - 04:26 pm: | |
Thank you David, for a difficult job (moderator), well done.
I shall be brief.
What testing are the samples being subjected to?
This issue has me concerned for several friends.
This may be my last post for a while, due to holidays and other real world concerns.
I will try to follow threads and keep up.
Have a great day.
|
David Gore
Moderator
Username: david_gore
Post Number: 341
Registered: 4-2003
| | Posted on Saturday, 04 December, 2004 - 08:46 am: | |
Hi everyone,
As I originally stated, my only concern was the impression I received that failures of the modified arms had started to be found. My interest was specific to the modified arms however the isolation of failure of the original arms to RHD vehicles only also aroused my "professional" curiosity.
So far, I have not heard of any failures of the modified arm and I have not worried about testing the original arms as the mode of failure is readily apparent [reverse cycle cyclic fatigue cracks originating at a forging "crease" on the shoulder of the boss]. The reason for this happening on RHD cars only is still to be determined.
Happy holidays - do you have a "leave pass" to escape the Michigan winter for more comfortable regions? |
William H. Trovinger II
Grand Master
Username: bill_trovinger
Post Number: 180
Registered: 8-2003
| | Posted on Saturday, 04 December, 2004 - 01:11 pm: | |
John;
I have several points to make on your latest post in this thread:
1) Let us get the record straight you claim in your post (of 02.12.04) I said:
“As I recall, it was YOUR goodself who very much suggested YOUR "right to KNOW" the details of the analysis of "363" fluid, being an analysis, sought by, paid for, and held by me. It was not available to you then, nor is it ever likely to be, despite your moral posturings (at the time) about the "obligations" etc.,of "helping" fellow "R-R" owners etc. You are correct in that I have not volunteered my "qualifications" nor do I feel obliged to do so.”
When in fact what I said was (post 20.08.04):
“On your comment “question any obligation on my part do do so,” I would not say you should look at it as an obligation but more as community service. Many in this forum donate valuable information, yes some has come easy but other information has come at expense to the contributor. Oh, not always a cash expense some more likely is through their personal effort and/or time and I am sure all would agree that time is more valuable then cash, unless one is under 30 that is.”
So unless you are going to get your facts straight I would ask that you refrain from making false claims like that!
2) Additionally, I have a hard time following you. When you make a claim nobody has the right to inquire as to the supporting information, like the case of the RR 363 issue. Yet, it seems you wish others to tell their whole lives story or else no credence should be given to their opinions. Remember the old expression “you can’t have your cake and eat it too” or maybe better would be the one “those who live in glass houses should not cast the first stone”.
3) For the most part I believe that the contributors to this great forum are taking the time to post answers not for self-glorification but rather in a true effort to help others and thereby help keep these wonderful motorcars on the road for all to enjoy. I think that great praise should also be given to the Moderators and Webmaster who keep this site going.
To the other forum readers;
Now I have said my piece and hope that this tread can get back to it’s original intent.
Best regards to all,
Bill
|
whunter
Grand Master
Username: whunter
Post Number: 114
Registered: 10-2003
| | Posted on Saturday, 04 December, 2004 - 02:41 pm: | |
Thank you David.
Much relieved on that issue.
I like Michigan winter weather, and driving in it, no pass for me and mine.
Today I saw a rusted out 1965 or 1966 RHD Silver Shadow on a roll bed wrecker, going down the highway.
What drew my attention was the broken steering gear hanging under it.
From now on, a camera will be in my pocket, to catch pictures like that.
You would have been impressed with the incredible volume and penetration of rust. |
John D
Unregistered guest
Posted From: 144.138.194.40
| | Posted on Saturday, 04 December, 2004 - 03:12 pm: | |
Thank you William. Upon refection and review of the posts referred to, I remain of the view that I was, perhaps not by intent, being placed under an obligation (to reveal the "363" formula) in order to serve a perceived "right" for members at large, "to know" . I did not (nor will I) table the analysis for TWO reasons. 1/ Publication COULD violate legislation concerning proprietory property rights etc;either here or the USA 2/ It may well have been flippantly dismissed as "inconclusive" or even "RUBBISH".
Moderator's Plea:
John, without divulging any technical data could you please indicate whether RR363 does contain an additive(s) not found in DOT3/DOT4. This will put our minds at rest without compromising privileged information and/or the source of the information. If you knew that you were never able to provide some indication of the findings; I suggest it would have been better to have said nothing about these tests than to "tease" all of us who have an interest in this subject with the fact that we will never know as we cannot afford the testing required to confirm our beliefs.
I have never expected anyone to tell me their life story, HOWEVER when one reads technically oriented assertions which contradict one's knowledge THEN I do not believe it unreasonable to ask for the contributor to declare the qualifications which enable them to adopt such a position. Similarly, if one is to continually dispute/contradict the opinions of QUALIFIED PROFESSIONALS who regularly contribute to this forum in good faith, then the same expectation should remain i.e that formal credentials be established.
In conclusion, I recall the occasion where I believe it was you, who, being upset about something on this forum, indicated your intention to withdraw, thereby ceasing any further contribution. It was I who expressed understanding, urging you to continue with your contributions since, like most people, I am appreciative of opinion when it is being offered as such.
For the record, I have no automotive qualifications, which renders me UNQUALIFIED (NO "standing" as they say!) to vehemently dispute or contradict technical opinion(s) offered by QUALIFIED professionals; ESPECIALLY when most of them are in agreement upon a particular point or issue. (J.G.Dare)
(Message edited by david_gore on December 05, 2004)
(Message approved by david_gore) |
John D
Unregistered guest
Posted From: 144.138.194.254
| | Posted on Thursday, 09 December, 2004 - 05:09 am: | |
In response, I can assure everyone that I acted in good faith in a genuine attempt to HELP members without any intention to "tease" etc. I believe that which I volunteered was preferable to saying nothing (about the report/analysis) insofar that, having due regard to legal constraints (and implications) I proffered a statement from which a reasonably clear inference could be drawn, i.e that having read the report, I remained confident with my decision (and that of many others;local and International) to use any proprietory brand DoT 4 spec.fluid in my S/Shadow, having personally done so now for almost eight years. I am not qualified to determine which constituent (if any) represents an "additive" and consider that I (and others) have provided sufficient guidance in previous posts for owners to reach their own conclusions in respect of any undue wear/noise or service concerns. If, in these circumstances, I remain seen to be,"witholding information", then I do not believe it could be reasonably compared to those who have advanced technical argument without supporting evidence to validate their sbmission.
(Message edited by david_gore on December 09, 2004)
(Message approved by david_gore) |
John D
Unregistered guest
Posted From: 144.138.194.214
| | Posted on Friday, 10 December, 2004 - 06:21 am: | |
Further to the foregoing I recently wrote to the U.S SAE, asking if they were aware of ANY need to periodically loosen and retorque ("every couple of years or so") Pitman Arm retaining nuts. A hard copy of the following reply is available and I quote verbatim. "I am responding as Chairperson of the SAE Fasteners Committee. You have raised a specific question about a fastener joint. The SAE Fasteners Committee covers dimensional,mechanical and performance characteristics of the fasteners themselves and dont get involved with the design of actual fastened joints. I would expect any requirements for loosening and re-tightening of fasteners would be covered under maintenence schedules for the particular vehicle sold. This would be similar to changing a timing belt at 60,000 miles for instance. You might want to enquire at the proper vehicle dealership where the particular vehicle is sold and serviced. Also, whoever made the assertion should be able to back it up with proper documentation" Chairperson, SAE Fastener Committee.[Message ENDS] I draw readers attention the FINAL TWO LINES and invite them to ALSO review (see prev. post/s) the comments from a U.S based OEM manufacturer of Pitman Arms (and arm nut retaining "kits") some of which are currently supplied to a well known make of military vehicle. It is perhaps opportune to remind readers (in particular, Series 1,Shadow owners) that this issue has been (and remains) SAFETY RELATED. I intend to politely inform our friendly and authoritive, U.S advisors, that the suggestion which called for this hitherto UNHEARD of "maintenence procedure", did NOT, in the initial instance, emanate from Australia.
(Message approved by david_gore) |
Richard Treacy
Grand Master
Username: richard_treacy
Post Number: 484
Registered: 4-2003
| | Posted on Friday, 10 December, 2004 - 11:52 pm: | |
Interesting. And, boy do I hate changing that stupid timing belt and tensioner on my BMW every 60,000 km (not miles) or less. Ridiculous design. At least the factory defines it though. |
Patrick Lockyer.
Grand Master
Username: pat_lockyer
Post Number: 153
Registered: 9-2004
| | Posted on Saturday, 11 December, 2004 - 04:46 am: | |
Richard. Try Maserati duplex chains and renold tensioner replacment,as the manual states hours!
Found a far easy way leaving engine in, just like the pitman arm torque safety proceedure not in the manual.
And it is to be shared with folk in due course.
Mercedes have always had chains and some BMW's.
Am i correct that RR never had chains just gears?
Next generation of most makers engines will have chains again i am informed.  |
Richard Treacy
Grand Master
Username: richard_treacy
Post Number: 486
Registered: 4-2003
| | Posted on Saturday, 11 December, 2004 - 05:31 am: | |
R-R always had sidevalves and/or overhead valves and they always had timing gears. That was before BMW and VW engines found their way in with overhead cams. Thank goodness for timing gears. For a short while, some had fibre gears which lasted just 80,000 miles, but the valves never foul the pistons when they fail. Better a rattly metal gear (rare) than a worn out fibre gear (always happens).
Chains are the worst by far. Ask any pre-1990 OHC Jag owner, or the owner of any pre-1989 Porsche. There is no scheduled maintenance on camshaft chains, but when they let go it's big trouble. Valves, pistons and casings disintegrate.
At least drive belts are a scheduled maintenance item, and very rarely let go if the belt and tensioner is replaced as defined. The only bad ones I know of are early Alfasuds with no belt cowling. A mate at university had one which lost its belt just one day out of its new car warranty, only one year on a new car back in 1975. Alfa sent him packing, so I replaced the valves for him: two were bent at 30 degrees. Incredibly, it happened at low RPM, waiting at the traffic lights, otherwise the pistons would have been destroyed too. |
Patrick Lockyer.
Grand Master
Username: pat_lockyer
Post Number: 154
Registered: 9-2004
| | Posted on Saturday, 11 December, 2004 - 06:10 am: | |
Richard The Ford Essex engine had the fibre gear and they would let go on the boss.
Regarding the cam belts breaking before schedule times.
Have had water pump seizure taking the teeth off the belts with disastrous results on some cars!
Oh well back to the pitman arm sorry,any thoughts on the directional torque within the sub frame and the deletion of the panard rod?
It bugs me that it is just rhd. |
John D
Unregistered guest
Posted From: 144.138.194.102
| | Posted on Saturday, 11 December, 2004 - 05:30 am: | |
Thank you Patrick, for yours of 11/12. At line 3 you refer to the "pitman arm safety procedure not in the manual", followed (at line 5) "and it is to be shared with folk in due course". ARE you saying that you will post published technical data to validate this statement?
Repetitious material from past posts removed
(Message edited by david_gore on December 11, 2004)
(Message edited by david_gore on December 11, 2004)
(Message approved by david_gore) |
John D
Unregistered guest
Posted From: 144.138.194.102
| | Posted on Saturday, 11 December, 2004 - 06:19 am: | |
Thank you Richard. I have owned 911s for 30 years and have never had a chain (OEM type) actually break (nor have any owners whom I know) however chain tensioners (PRE hyd.feed; mains oil pressure type) have certainly been known to fail, causing the chain to "skip" a tooth (or two) with the drastic consequences which you correctly
describe.I suppose that is why "R-R" seem to have had an aversion to chains/tensioners etc.,the immortal "Merlin" deploying shafts/bevel gears for valve actuation and other accessory items. ooOOPPS!!...no, NOT my 911 chain tensioner, but silly ME (and others) wandering OFF the Thread/topic, which is "PITMAN ARMS". Let us resume our focus thereon, lest unrelated topics provide avenues of diversion from the prime issue/s and specific points currently under active discussion herein.
MODERATOR'S COMMENT:
Gentlemen Whilst we strayed from the original topic onto other topics including references to non-R-R/B vehicles; I used my discretion in allowing these references to be posted as a courtesy to Richard Treacy for his unwavering support of our website. If you wish to discuss non R-R/B vehicles with our contributors, please use the direct contact facilities included in the USER LIST available to registered users.
(Message edited by david_gore on December 11, 2004)
(Message edited by david_gore on December 11, 2004)
(Message approved by david_gore) |
Patrick Lockyer.
Grand Master
Username: pat_lockyer
Post Number: 161
Registered: 9-2004
| | Posted on Saturday, 18 December, 2004 - 10:18 am: | |
Has anyone in the Uk a cracked drop arm as i can have a full test carried out to determine where and how the fracture started.
There may be more of a chance of a RHD car with the numbers produced and still with the old type arms in use here to this day. |
Patrick Lockyer.
Grand Master
Username: pat_lockyer
Post Number: 253
Registered: 9-2004
| | Posted on Tuesday, 25 January, 2005 - 09:51 am: | |
Well today almost two years since i carried out my last torque check proceedure on the the pitman arm nut.
All was not as it should be today! pix to follow in due course with more details.
I am more convinced that the failing of the arm is brought about by the nut excercise not being carried out on a two yearly basis with other factors present.
|
John Dare
Grand Master
Username: jgdare
Post Number: 108
Registered: 12-2004
| | Posted on Tuesday, 25 January, 2005 - 10:26 am: | |
Please ensure that any pictures are sufficiently clear for me to on forward to a U.S manufacturer of Pitman arms (and retaining nut "kits") as OEM supply for military "Hummers" AND the Chairperson of the U.S based SAE (Fasteners Section) who I suspect is an engineer with GM, who I do believe manufactured the Shadow steering box. As recorded in previous posts BOTH of these (U.S) parties remain blissfully unaware of the "need" to periodically re-tightening or otherwise interfere with pitman arm nuts and THEY are the people who DONT have problems with the Pitman arms on THEIR(LHD) steering boxed Silver Shadow vehicles. HHhhhmmm. |
Patrick Lockyer.
Grand Master
Username: pat_lockyer
Post Number: 255
Registered: 9-2004
| | Posted on Tuesday, 25 January, 2005 - 10:35 am: | |
This is for some that know what i am getting at,I realy must retire to bed.
More tomorrow.
|
Patrick Lockyer.
Grand Master
Username: pat_lockyer
Post Number: 256
Registered: 9-2004
| | Posted on Tuesday, 25 January, 2005 - 06:02 pm: | |
Ok J Dare, i will now at this point let you carry on with the final conclusion on this serious matter as you have all the interested partys on hand to forward my details so far.
Thank you! |
Patrick Lockyer.
Grand Master
Username: pat_lockyer
Post Number: 258
Registered: 9-2004
| | Posted on Wednesday, 26 January, 2005 - 05:28 am: | |
Some more pix to help you JD,oh such silence.
 |
Robert Chapman
Grand Master
Username: shadow
Post Number: 157
Registered: 5-2003
| | Posted on Wednesday, 26 January, 2005 - 09:18 am: | |
Hi Patrick ,
These pictures have come out very dark and I am unable to see clearly inside the boss.Would it be possible to get more light on the subject. |
Patrick Lockyer.
Grand Master
Username: pat_lockyer
Post Number: 259
Registered: 9-2004
| | Posted on Wednesday, 26 January, 2005 - 09:49 am: | |
Robert hope this helps.
I have concluded my checks tests it remains for J Dare to conclude with his ramblings on the issues.
I myself will at this point confirm that there is no problem with the early arm it is other related faults that are the problem.
Pix i hope will be better or i will take some more when poss.
 |
John Dare
Grand Master
Username: jgdare
Post Number: 115
Registered: 12-2004
| | Posted on Wednesday, 26 January, 2005 - 01:19 pm: | |
Thank you Robert, for yours at 10:18 today re detailed enhancement of various photographs presumably tendered as some form of decisive evidence. Prior to pondering any answers or offering any conclusions (speculative or otherwise) in relation thereto, are you aware of the actual QUESTION which is (apparently) being advanced? |
Robert Chapman
Grand Master
Username: shadow
Post Number: 158
Registered: 5-2003
| | Posted on Wednesday, 26 January, 2005 - 02:21 pm: | |
Patrick,
Thanks that quite a bit better and I believe I can see the start of a crack in the first picture of he second lot,it appears to have started in the same point as usual in the same section of the boss.
I thought I could see it in the first picture but could not be sure,but in the second it look even more suspect.
I am looking at an arm that has started to crack but was detected before breakage and it look identical(except no rust).
Although it is difficult to see in the picture it would appear that the splines are worn(fretted)by movement and the spring washer does not show a full contact area and looks like it has lost its tension.
It appears the nut had been loose (as in lost its correct clamping tension)allowing the arm to move on the splines which becomes self perpetuating.
The arms we have detected cracked and removed for further inspection have definitely not been loose in fact have needed to be removed by hydraulic puller. |
Patrick Lockyer.
Grand Master
Username: pat_lockyer
Post Number: 260
Registered: 9-2004
| | Posted on Wednesday, 26 January, 2005 - 04:28 pm: | |
Robert i can assure you it has been removed by a hydralic puller and that when it let go it did with the usual crack!
The arm is Ok.
I have a check that i do and it was not correct this time,will let you know all details in due course after J dare gives his write up or SHUTS up. |
John Dare
Grand Master
Username: jgdare
Post Number: 117
Registered: 12-2004
| | Posted on Wednesday, 26 January, 2005 - 05:13 pm: | |
The foregoing appears contradictory. It says, "it let go it did with the usual crack", but THEN I read, er.."the arm is OK"(?) What is being suggested here and (more IMPORTANTLY) what was the original QUESTION again? |
Patrick Lockyer.
Grand Master
Username: pat_lockyer
Post Number: 261
Registered: 9-2004
| | Posted on Wednesday, 26 January, 2005 - 06:01 pm: | |
Any engineer will know the term so shut up. |
John Dare
Grand Master
Username: jgdare
Post Number: 118
Registered: 12-2004
| | Posted on Wednesday, 26 January, 2005 - 06:22 pm: | |
So I can only "guess" you are implying that it (the arm) was TIGHT?. SO very TIGHT that the extraordinary FORCE of a hyd. puller was required to remove it from the splined shaft, hence a "cracking" type of noise as you put it. If I am correct of course. IF so, then THAT condition is IDENTICAL to that already recalled by Robert C in his post at 3;21, refer his final two lines where the same TIGHTness (Not LOOSENESS!!) also required his application of hyd. force only to find a cracked arm (pre-existing) usually at the same location. And your question or point, again, was..was...?? |
Patrick Lockyer.
Grand Master
Username: pat_lockyer
Post Number: 262
Registered: 9-2004
| | Posted on Wednesday, 26 January, 2005 - 06:33 pm: | |
I give up.
You are a twit. |
John Dare
Grand Master
Username: jgdare
Post Number: 119
Registered: 12-2004
| | Posted on Wednesday, 26 January, 2005 - 06:57 pm: | |
When I last dared to respond to the likes of the foregoing, my dismissive reply (and that to which I responded) was deleted. Accordingly, I feel I am inhibited from delivering a reply, notwithstanding my ability to counter ANYTHING that is ever likely to be addressed to me upon this forum. Quite OK however for some to defame me (10;31 today) Quote; "Ive just realised you are a fraud". Ahh..."Australia Day"; reminding me of fairness, impartiality and equal opportunity for all. Depending upon who you are and where you are domiciled of course. |
Richard Treacy
Grand Master
Username: richard_treacy
Post Number: 527
Registered: 4-2003
| | Posted on Wednesday, 26 January, 2005 - 07:00 pm: | |
Thanks David, Robert and Patrick.
I have observed this thead a little bemused of late. At least, through the smokescreen, we can observe that there is indeed an important issue to address here.
Pictures can tell lies, but I do observe the mark apparent in each shot. Cannily, as pointed out already, that mark is exactly where these levers crack. Is this one about to let go I wonder.
I looked at my split Pitman arm last week, and apart from the tack weld imposed to move the car into the workshop, it is a carbon copy of the one posted by David last November.
Robert, would you Magnaflux this one, X-ray it, throw it away or otherwise ? If possible, I would throw it away and fit the stronger one superseding it. In any case it is the weak original type and as such is suspect at best. Perhaps David can offer a metallurgist's view ?
As for periodic retightening, let's not get hostile. If it makes sense, maybe it should be done. Afterall, there are other non-scheduled retightenings which are worthwile, such as rear axle U-bolts on cars with live axles. I have no view on retightening other than to be appalled that such a safety-critical item could ever need any attention at all.
Take it easy guys.
RT.
PS our car is one of the very last with non-compliant suspension, and has the Panhard rod. I know of failures of Pitman arms on cars with compliant suspension (Panhard rod deleted) alike, and have never heard of any connection between suspension types and Pitman arm failures. The only relevant difference between UK and Australian-delivered cars is the stiffer Oz suspension. But hell, this is all clutching at straws. LHD cars may just be that tiny bit less susceptible, but that's not good enough is it ? |
Robert Chapman
Grand Master
Username: shadow
Post Number: 159
Registered: 5-2003
| | Posted on Wednesday, 26 January, 2005 - 09:27 pm: | |
Hi Richard,
I would very carefully clean this arm and then Magnaflux it as I believe I can see the start of a crack in second valley (root)passed the alignment flat spline at about 2 o'clock.
And as you also observe this is always where they start and I am looking at one that looks exactly the same.
I would personally not refit this one,I think it would wise to change it now,but of course Pat is on the spot and that dicision will be his.
In my opinion the cause is quite straight foreward,there simply isn't enough material around the boss(this is why the new arm was made twice the thickness) and the expanding pressure of the tapper eventually splits it through,starting from the root of the spline.
I believe the reason why LHD arms don't crack is the same reason idler arms don't crack(after all they recieve the same road shocks and vibration),that is there is more material in the boss and the positioning of the removal lugs relitive to where the arm joins is different.
Whilst I understand that retightening may be required on some components that has come to light through milage,and different methods of performing jobs are not always in the mamual, I can't believe this is so of steering components,after all none of us reported the nuts as being loose!.And since undoing the nut would not release the pressure exerted by the tapper (they all have to be hydraulically pulled off)what possible use would it serve, only perhaps to stress the threads in the relatively thin half nut.Sorry but I cant see any technical or practical evidence to support this theory. |
Patrick Lockyer.
Grand Master
Username: pat_lockyer
Post Number: 263
Registered: 9-2004
| | Posted on Thursday, 27 January, 2005 - 12:06 am: | |
Hi Richard, Robert,first the checking proceedure had show up that the torque had varried on the the nut.
removal of the nut then reveled movement on the spline ot the spring washer sorry i had not made this clear as i only put the pix up due to the parret of many hollow words.
The examination of the box shaft also was to show movement within the splines.
The pictures are of the same arm,it was cleaned for the crack testing and that proved ok.
I am not happy until the arm has futher tests and has now hopefully on its way for xray.
Im a bit short of time at pressent but will put up some more pixs and let you know further,you have touched on one prob that i will agree on.
|
Patrick Lockyer.
Grand Master
Username: pat_lockyer
Post Number: 264
Registered: 9-2004
| | Posted on Thursday, 27 January, 2005 - 12:16 am: | |
Richard Robert,the other main worry if i am correct is the modified arm giving up on a longer time within the splines as i stated somwhere along the lines. must fly. |
Patrick Lockyer.
Grand Master
Username: pat_lockyer
Post Number: 265
Registered: 9-2004
| | Posted on Thursday, 27 January, 2005 - 06:07 am: | |
Richard Robert David.
First the movement is only on the lower part of the taper due in my opinon to the stress angle of the arm to the boss.[With other stated faults] and confirmed by the removal need of the hyd puller.
This is why it is important to check the torque of the nut every two years.
However the check is not just the torque factor it has to be slackened and retorqued to the same centre punch marks,this nut was not loose.pix shows marks,the two marks are the position diference from two years ago.
If they dont line up something is going wrong,this was the case with this one.
Time to investigate.
After removeing the nut it was soon apparent that the lower splines of the arm had stress movement showing up on the washer pix above.
The mark on the arm spline face is the spring washer split digging in,there are three and it happens that one is in the suspect position.
It is my opinion that the half nut is the main failing of this set up it is just not strong enough and needs more torque ,as you said Robert it is not an ideal situation to have to retorque a component like this,
However i have yet to have a failure,we will see what the x ray shows up.
If ok i will refit with new nut and check yearly.
I beleive the crack starts on the lower spline area working outwards if the movment goes undetected for a long period of time.
As for the modified arm if all this is correct i can see the new ones failing on the splines over a longer space of time.
Robert your veiw on the arm running up the splined taper is well noted but i can see no sign of it on the arm or shaft.
Has the mod arm a new nut and washer set up.
Richard, How many years and miles before the arm needed to be replaced on the Bentley i am still working on the RHD factor.
 |
Richard Treacy
Grand Master
Username: richard_treacy
Post Number: 534
Registered: 4-2003
| | Posted on Thursday, 27 January, 2005 - 06:39 am: | |
Pat,
Ours failed in 1999 when the car was 27 years old at around 195,000 miles. Despite the signals from the Pitman arm and final drive crossmember mounting problems, this car has had a very gentle life, mostly swanning around on Canberra's super smooth, wide curved avenues with few intersections.
I do understand that many failures occurred on fairly new cars in the late 1970s and early 1980s especially in the UK, and since then the occurrence has settled down to a more moderate but still significant rate.
It all reinforces my hatred of all tapered fixtures.
RT.
|
John Dare
Grand Master
Username: jgdare
Post Number: 124
Registered: 12-2004
| | Posted on Thursday, 27 January, 2005 - 07:02 am: | |
Like it or not the United States is the most progressive and industrialised nation on the planet. They lead as others follow. See my previous posts whereby an U.S based OEM manufacturer of Pitman arms (AND nuts therefor!) for MILITARY spec. vehicles (Hummer) and the decidedly AUTHORITIVE (as opposed to spectating and speculating owner/enthusiasts) Society of Automotive Engineers (SAE) U.S chapter, have NEVER heard of the mysterious Re-tightening procedure (at some "predetermined" interval) with ONE of them stating that the procedure could in fact CAUSE problems!. I am embarrassed to think that my many U.S friends and contacts read all of these bizarre "loosen and tighten" theories as now advanced by assorted experts. Experts who of course "know" better than GM engineers etc., who chair (honorary) the Fasteners section within the U.S/SAE. And as for a Pitman arm MANUFACTURER.. well, what would HE know? |
Patrick Lockyer.
Grand Master
Username: pat_lockyer
Post Number: 266
Registered: 9-2004
| | Posted on Thursday, 27 January, 2005 - 07:28 am: | |
In that case i am sure you will get them to confirm that the splines on the modified arm will not fail over a longer period of time.
We all wait for your now stated facts from them on the issue. |
John Dare
Grand Master
Username: jgdare
Post Number: 125
Registered: 12-2004
| | Posted on Thursday, 27 January, 2005 - 01:39 pm: | |
P.L; Once again you appear to maintain the rather bizarre expectation of wanting others to interpret YOUR question (or assertion) or whatever it is that YOU are attempting to submit or advance. It seems rather like a "guessing game", as opposed to a simple quiz, but nevertheless, being bold and adventurous I will ASSUME (please advise if incorrect) you are implying that UNLESS your periodic nut "re-tightening" procedure is adopted, then even the later R-R modified arm "boss" will ALSO crack as per the earlier version. IF that is your submission, then in response to your second para. as above, "we all wait for your(?)now stated facts from THEM on the issue", I invite your attention to evidence supplied from AUTHORITIVE (and "FACTUAL", since they WOULD "know"!!) sources, IN response to your SPECIFIC claim. Such relevant submissions were posted by me under this thread on Dec.2nd at 1;17pm (Mnfr.) and further, on Dec 10th at 7;21am (US/S.A.E). Both parties essentially confirmed that your proposed procedure is UNHEARD of (under ANY circumstances!) within the auto. engineering & mfg. fraternity; UNRECORDED (anywhere) within the annals of auto/eng. history (incl.MILITARY auto. service manuals!) and could in fact lead to and/or CREATE problems, including the particular kind now under discussion. |
David Gore
Moderator
Username: david_gore
Post Number: 377
Registered: 4-2003
| | Posted on Thursday, 27 January, 2005 - 04:12 pm: | |
Gentlemen [and others],
My apologies for the absence of my editing finger over the past few days as I have been preoccupied with other matters that have had to take precedence over Forum moderation. I note there has been a resumption of inappropriate comments much to my disappointment and I again ask our "combatants" to respect the latitude they are given to avoid imposition of undesirable constraints on direct posting.
Thank you Pat for your photos and I would dearly love to get my hands on one of these arms or at a minimum, the results of careful fluorescent dye penetrant testing of the splines - there are some inherent difficulties in getting good Magnaflux[R] testing of this area due to the component design and crack direction and I doubt if X-rays will be any better in picking up incipient cracking until it has progressed a considerable distance into the boss.
If anyone has a cracked arm that they can cut and remove a section say 20/25mm thick from the boss to expose the actual transverse fracture surface for photographing; this will help confirm the mode of failure. the stress levels involved and most importantly the number of initiation sites and direction of crack propagation.
I am particularly concerned that Pat's arm does not show the forging crease evident on Robert's original example and I now suspect more than one factor may have been responsible for the failures - the use of half instead of full nuts for retention has the potential to create problems with loss of torque over time as suggested by Pat and the subsequent "fretting" is a very well-known cause of fatigue cracks in parts subject to cyclic stressing.
My only comment about John Dare's information from the US is that engineering excellence and/or ineptitude is not conferred by geographic location alone. The value of advice given is entirely dependent on the information provided by the person asking the question and the diligence/experience of the "expert" providing the answer. In all cases; "one look is worth a thousand words" and the only ones with this privilege so far are Robert, Richard and Pat.
This has now developed into a very important topic thanks to the persistence of our contributors. |
Patrick Lockyer.
Grand Master
Username: pat_lockyer
Post Number: 268
Registered: 9-2004
| | Posted on Friday, 28 January, 2005 - 05:53 am: | |
Well the arm is on its way for testing.
I have no knowledge on this testing procedure it appears that it is not done by x ray but by several other means,i can only guess at what was meant by do i want the stress dressed out if the arm is ok i said yes!
Needless to say that the checks are used it the aircraft industry,more on this when the hopeful results will let me use the arm again as a new modified one priced at £400-00+ disgusting.
Crewe have not heard the last of me on that.
From the powers of b it appears that the nut washer set up are still the same on the modified arm.
I just don't like it and needless to say i am going 21st century with help from my Son on that whatever arm i use.
More in due course on the return of an early hopefully passed ok arm.
|
Richard Treacy
Grand Master
Username: richard_treacy
Post Number: 538
Registered: 4-2003
| | Posted on Friday, 28 January, 2005 - 06:17 am: | |
Pat,
Now you see why I was so.. annoyed (being polite). First the humiliating failure itself, the flatbet truck, then the consternations over the safety implications, and finally a sting in the form of the cost of a new one. They should give you a new one free of charge and a bribe to shut you up. To be fair, the Sydney agent sold us one at cost, around £250 including freight, the then punative import duty, and also including a crazy sales tax now replaced by a sensible 10% VAT, in recognition of the embarrassing nature of this fault. I looked at the invoice last week just for fun.
Dressing out stress is, I assume, filing away the fatigued metal and polishing the whole area smooth to stop a full-scale crack from developing. |
John Dare
Grand Master
Username: jgdare
Post Number: 126
Registered: 12-2004
| | Posted on Friday, 28 January, 2005 - 08:55 am: | |
Being the gentleman that I am, I obtained MY robust,stronger, modified design Pitman arm entirely WITHOUT charge, ie "FREE" (absolutely!) "GRATIS" (of course.. as I EXPECTED it to be!) There was nothing "wrong" (as such) with my original arm, albeit the inherent weakness occasioned by its (comparatively) flimsier,lighter and less substantial mounting point construction thereby representing a prima facie case of LATENT DEFECT. However, in the interest of safety, I took pre-emptive action, not only for myself but (as with the issue of speed) in consideration for the safety of OTHER road users, especially those who might be approaching me from the opposite direction. I note that the original weaker arm spectacularly FAILED to indicate ANY evidence of cracking, despite the nut failing to undergo the mysterious "LARP" (The "X" Files?) i.e Loosening And Retightening Procedure, at any time during its (then) service "life" of approx. 28 years. |
Richard Treacy
Grand Master
Username: richard_treacy
Post Number: 539
Registered: 4-2003
| | Posted on Friday, 28 January, 2005 - 09:21 am: | |
"jOHN",
WITH "all" due ie etc sic respect,,,,,, "WHAT" is your (point) ? |
John Dare
Grand Master
Username: jgdare
Post Number: 127
Registered: 12-2004
| | Posted on Friday, 28 January, 2005 - 10:14 am: | |
R.T: Well since I am easily confused, I was wondering why some people "have"(or are expected) to pay 400+ pounds (see prev.post at 6;53am) for something that I readily and easily received (ex UK)absolutely FREE. Furthermore, I was recording the fact that despite no LARP (of the nut) my original (weaker) arm had NOT developed any incidence of cracking. Ergo, the much vaunted periodic Loosening And Re-tightening Procedure (LARP) would appear to be not only dubious, but irrelevant (as a protective/inhibiting factor) in relation to the cracking as variously witnessed. But speaking of "points", may I quote my latest reply (as received) in relation to this particular point of issue as tirelessly promoted by others to date. Quote: "In my 37 years of Automotive experience, I have never heard of a periodic loosen and retighten procedure on any tapered spline application"; Unquote. But then this (and others which I am expecting) merely came from the USA, the country which had the technology to end WW11 and 24 years later (less than the age of most S/Shadows!) thought they just might put a man (or two) on the moon, and then bring them back to relate the experience. Would they "know" (about LARP) IF it were a CREDIBLE (and accepted) procedure?. I suspect they might. |
David Gore
Moderator
Username: david_gore
Post Number: 379
Registered: 4-2003
| | Posted on Friday, 28 January, 2005 - 10:30 am: | |
John, with due respect I suggest you may be overlooking the essential reason for the periodic checking of the nut torque - it currently appears to me that there is a problem specific to R-R/B vehicles whereby the locknut may become loose in service and result in fatigue cracking.
I remain concerned that current indications suggest there is more than one reason for the cracking and again why it is confined to RHD vehicles. |
John Dare
Grand Master
Username: jgdare
Post Number: 128
Registered: 12-2004
| | Posted on Friday, 28 January, 2005 - 01:06 pm: | |
Thank you David. For all PRACTICAL considerations the "age old" tapered spline "fail-safe" (?) connection appears to provide the effective prime attachment/ holding function, hence the massive force needed to displace/remove the arm even WHEN the so-called "retaining" nut is detached, let alone "loose", or looser than it "should" be. A loose NUT does NOT, a LOOSE Pitman arm MAKE, for if it DID, you wouldnt need huge hyd. removal forces (common to tapered spline applications) to remove such an arm (sans nut) particularly if it was considered to have been sufficiently loose as to induce fretting upon a tapered connection. The alien process of periodically "loosening and retightening" (AND re-USING??) the same "half" nut/s "just to be on the safe (?) side", could, for various reasons, produce a wonderful variety of conflicting (and incorrect) torque values anyway. However, if P.L and others are correct, perhaps we should all apply this unheard of LARP ritual to the nut at our (tapered spline) steering wheel to hub connection, a point which also receives road shock loadings, hence typically worn bushes/parts in the R-type upper steering column region. Oh NO!!... NOW I will have someone telling us thats why many Mk6/R type steering wheels display cracks radiating from the hub, ie due to failure to deploy LARP. Oh dear. |
David Gore
Moderator
Username: david_gore
Post Number: 381
Registered: 4-2003
| | Posted on Friday, 28 January, 2005 - 02:46 pm: | |
John, I think we should all keep an open mind and not lock ourselves into rigid positions as the recent input indicates the problem may well be multi-faceted and the eventual findings may embarass all of us who have expressed an opinion so far and that includes myself. One thing that I am now certain about is that a simple explanation for the problem almost certainly does not exist and there is an increasingly valid argument for crack testing of modified arms on high-mileage vehicles to see if cracks have developed and if so; how far they have developed [after all most aircraft flying right now have cracked components that have defined service lives and will be replaced during scheduled maintenance before catastrophic failure occurs - these service lives have been determined from the extensive testing and monitoring that takes place throughout the life of the aircraft from initial prototype to the last one that stops flying].
The fact that power separation is required to separate the arm from the spline is no guarantee that fretting and subsequent cracking is impossible in localised areas due to deformation of the material within its elastic limits whereby it can move locally yet not move in the overall sense. The use of pre-loads to generate compressive stresses within a material to counter tensile stresses subsequently generated in service is not uncommon and the fastener torque specification is based on all the factors involved to generate the required compressive strength. It is possible for the nut to relax and release the critical compressive stress whilst the arm remains firmly located on the spline giving the superficial impression that all is well when it certainly is not. |
Robert Wort
Prolific User
Username: robert_wort
Post Number: 78
Registered: 12-2004
| | Posted on Friday, 28 January, 2005 - 04:34 pm: | |
Actually, this isn't peculiar to RR/B's or Pitman arms. In my days as a mechanic, we had to loosen and retension the nuts on 1600 cc Volkswagen cylinder heads as they were prone to come loose and blow the head ring (gasket) and crack the cylinder heads. I will offer no further comment. |
Robert Wort
Prolific User
Username: robert_wort
Post Number: 79
Registered: 12-2004
| | Posted on Friday, 28 January, 2005 - 05:47 pm: | |
Sorry, I lied! One further comment. This procedure had to be done every major service
(especially on the Kombis), during the warranty period. The first signs of trouble were popping sounds on acceleration and if this wasn't rectified quickly, it would result in cracked cylinder heads. |
Patrick Lockyer.
Grand Master
Username: pat_lockyer
Post Number: 271
Registered: 9-2004
| | Posted on Friday, 28 January, 2005 - 06:03 pm: | |
Robert w.I have in my time done many things that have not been known in the trade to get over probs as you have done.
Mind you some don't always work.
Stretch bolts are now the norm to get over the head gasket failures.
I can tell you some stories about my beloved Jaguars starting with the mk1 2.4 with the solex carbs but at the moment the old brain is on the glenfiddich and pitman arms.
|
John Dare
Grand Master
Username: jgdare
Post Number: 129
Registered: 12-2004
| | Posted on Friday, 28 January, 2005 - 06:12 pm: | |
Yes indeed, and still the case with 911 head/case, studs and nuts as are the R-type head nuts which might deserve a "tweak" (as with other ALUM. head, nuts or bolts) maybe Shadow exh. manifold nuts too, and "Look Ma..not a TAPERED fitting in sight!". Moving ON.... Years ago, I met a person who had been Chief Engineer with a British (not R-R) car manufacturer, during which time he had been OFFICIALLY invited to the Soviet Union to advise on brake upgrades for the Fiat derived Lada. Seemingly, the original design could not cope with differing driving and general operating regimes encountered within that country. Due to the political sensitivity at the time, the "secondment" had to be sanctioned, arranged and supervised by the Foreign Office, my friend recalling his "5-star" treatment and accommodation which he (not suprisingly) hoped would only be of a temporary nature. Apart from being taken on wild boar hunting expeditions, he had the pleasure of a guided tour of the Kremlin garage (Leonid B presiding!) duly noting (but NOT commenting upon) the apparently pluralist nature of socialism. Through unsmiling interpreters "black" comments of a jocular (??) nature were referenced in respect of anyone who designed (let alone MADE) a faulty braking OR STEERING related component within the Mother country. NOW... had I been the visiting consulting engineers quivering ASSISTANT, and the good Leonid had handed ME a Pitman arm (exhibiting the SAME type of crack/split and at same location as "that" one from Crewe) and given me 30 seconds to provide the CORRECT explanatory "answer" (lest I earn a train ride east) THEN, despite not being a descendent of Einstein, I would have BLURTED out..... "its not THICK enough at one end !!!!!" . Amid perspiration, I would have hoped and PRAYED of course, that it wasnt of Soviet manufacture and regardless of its origin, that the grim faced interpreter had not somehow taken a dislike to me! |
Robert Chapman
Grand Master
Username: shadow
Post Number: 160
Registered: 5-2003
| | Posted on Friday, 28 January, 2005 - 09:45 pm: | |
Hi Robert W,
With respect I think JD is quite correct ,the re-tensioning of cylinder head bolts or nuts is a completely different concept to the periodic loosening and re-tightening of a tapered splined joint and cannot be compared.
The notion that tapered joints should be regularly loosened and re-tensioned in my opinion is nonsensical and fraught with danger.
Should we apply this practise to track rod ends, ball joints,idler arms ,and what about axle drive yokes! should we be removing rear hubs and carrying out this procedure.
I fear that there are to many red herrings being thrown into this issue,the facts are that the nuts dont come loose,early arms dont crack,the new arms dont crack,idler arms dont crack,only the arm with the counter bore machined in it to except the spring washer crack, the cracks always start at the same point,they always crack through the thinnest section,R-Rs answer to the problem was to put more material around the boss,the securing nut cant stand tentioning more than about 3 times before it starts to pull the threads.
With due respect PL in my opinion the theory that you can mark something and re-tension it and it should line up each time is open to so many variables as to make the results meaningless.
I thing the only embarrassment to come out of this is will be the number of times we aloud ourselves to be lead around the houses and up the garden path. |
Robert Chapman
Grand Master
Username: shadow
Post Number: 162
Registered: 5-2003
| | Posted on Friday, 28 January, 2005 - 10:13 pm: | |
Hi Patrick,
I am sure you could tell us a tale or four about your Jag's but first please tell us the full story on the brake and engine mods you have carried out on the Shadow.I am sure many readers would be very interested in its performance. |
Robert Wort
Prolific User
Username: robert_wort
Post Number: 83
Registered: 12-2004
| | Posted on Friday, 28 January, 2005 - 10:23 pm: | |
Thanks Robert C. I stand corrected.
Rob. W. |
Patrick Lockyer.
Grand Master
Username: pat_lockyer
Post Number: 272
Registered: 9-2004
| | Posted on Saturday, 29 January, 2005 - 12:29 am: | |
Robert C.
Think about the minis 1100's etc of the 60's 70's 80's flywheel to crank taper,many times of removal in the engines life more in due course.
However this is the first time in my posession of many years that the arm has been removed.
Have worked out a modern way to get over the spline movement failing of arm if mine comes back ok, and ofcourse on the modified type.
Ps did i say Shadow 1 i don't think so.
Realy must fly. |
Patrick Lockyer.
Grand Master
Username: pat_lockyer
Post Number: 273
Registered: 9-2004
| | Posted on Saturday, 29 January, 2005 - 06:28 am: | |
Robert C If the marks are not in the position or in very close proximity then it is my veiw that something is going wrong.
The check i have done for years has been ok until this check showed up the diferental.
As you stated there was a problem that has been bought to the attention of all from your original postings,it was my reply to the possible causes
that could lead to the possible failings of the arm.
I had no idea that what i have found was so simple
but i will confirm to you that the more i get into the probs it is pointing that it is a total failing with the nut and spring set up.
It is my belief through the lower stress movement on the spline it causes expanding pressure within the boss,it lets go and then the second stage takes over;greater movement with the arm causeing the break to look as though it started from the outside before the boss lets go completly at the time of most leverage,Parking hitting the kerb etc.
Today have been informed that the nut washers have never been supplied on there own to any dealers.
I find this hard to believe if you say that you
cannot use more than three times.
Any way i have ordered two so as to do further checks either way.
I await the result of the arm before i conclude on the rest of the findings.
And if it is ok on tests i will reuse it of course
with all the mentioned causes not pressent on my car!and a simple modified set up.
I am sure you will work that out, 21st centry stuff and a little more.
The box shaft splines are in first order as they should be being very very hard.
Robert keep going round the garden path it sure will lead you to my theory.
And please don't assume you have to tighten track rod ends etc remember angles forces stress.
pix of the s/box shaft.
 |
John Dare
Grand Master
Username: jgdare
Post Number: 132
Registered: 12-2004
| | Posted on Saturday, 29 January, 2005 - 08:46 am: | |
Allow me to bypass "The X Files" and cut to the chase. Scene 1. Some Pitman arms develop fractures, these generally being the ones with the milled washer "recess", the creation of which obviously translated to LESS metal at the mounting boss area. Scene 2. Following their awareness of the breakages (by fracture) and their assessment of the most PROBABLE reason for the breakage, R-R manufactured arms with MORE metal, thereby creating an INCREASED (larger!) physical DIMENSION at the mounting boss area. Scene 3. The new, stronger arms do NOT develop any cracks, NOR provide any reasonable indication that they are LIKELY to do so. THEN....everyone lived happily thereafter, being convinced yet again, that in most cases, SIZE DOES MATTER! |
David Gore
Moderator
Username: david_gore
Post Number: 383
Registered: 4-2003
| | Posted on Saturday, 29 January, 2005 - 09:08 am: | |
A brave call John Dare - my original opinion about the failure was the same as Robert Chapman's however the information posted by Patrick has created enough doubt in my mind to cause me to consider other possibilities for causing the cracks may also exist and that this should be investigated further particularly on high-mileage vehicles to see if fixing the apparent problem hasn't also created the opportunity for secondary problems to come into play later in the service life of the vehicle - see RT's comment on the rear crossmember problems AFTER the factory modification. If the cracking is confirmed and the probable causes identified; then we can debate what are the best preventative measures. |
John Dare
Grand Master
Username: jgdare
Post Number: 133
Registered: 12-2004
| | Posted on Saturday, 29 January, 2005 - 11:44 am: | |
When R-R first became aware of the physical failure/s of such a CRITICAL (safety related) component, they responded by modifying the arm to make it stronger in the mounting boss area. Did someone say, "lets make the boss area 10% larger.. or.. 25% maybe, or 50%" (whatever) and then simply sign off a "lets see" prototype for production? . Of course NOT, for given the DEMONSTRATED weakness in the "original", they would have run computer programmed stress tests (on a variety of sizes and designs) after which time pilot samples would have undergone "destruction" type tests (FOCUSING upon the splined mounting area) to ensure their integrity and confirmed suitability as a worthy and RELIABLE service replacement for the previous design. R-R had testing devices which simulated the cyclic opening and closing of doors and even testing rigs such as their affectionately named "Squirming Irma" (a weighted model of the human posterior) to test the durability of seat cushions. If those less critical parts were tested for safety (door locks/hinges etc) and durability (seat cushions/springs) you can be sure that they would have had their analytical laboratory, metall./ engineering sections thoroughly check and trial TEST the "new" Pitman arm to avoid any possibility of a recurrence of the original "KNOWN failure" condition. Manufacturers dont always get it "right" the first time (hence "recall" programmes) but not suprisingly, usually do so on the second occasion, given that FURTHER failures (especially those of an IDENTICAL nature in such a SAFETY CRITICAL area) would in all probability, expose them to an unacceptable level of legal liability, which under such circumstances, could well render their position indefensible. |
Robert Chapman
Grand Master
Username: shadow
Post Number: 163
Registered: 5-2003
| | Posted on Sunday, 30 January, 2005 - 07:19 pm: | |
Hi Patrick,
In answer to your post of 29/1,sorry I think you may have misread my post, I didn't say you had said it was a Shadow 1.
So I presume then that it was a SS11,and that would explain your reason to covert to larger carburettors but I am still dying to know the other details,what is the size of the larger valves you have fitted ,what are the cam event figures,and how did you get the comp ratio up and what to,how does it perform on those country roads in your area. |
David Gore
Moderator
Username: david_gore
Post Number: 384
Registered: 4-2003
| | Posted on Monday, 31 January, 2005 - 04:07 pm: | |
John,
You have not addressed my comment in its entirety - yes R-R did fix the "apparent" cause of the cracking but does the new information indicate that secondary causes are present which MAY ALSO cause cracking but at a much greater mileage - I would prefer to remain cautious on this until the facts reveal that we either have a problem or we don't. |
John Dare
Grand Master
Username: jgdare
Post Number: 139
Registered: 12-2004
| | Posted on Monday, 31 January, 2005 - 06:32 pm: | |
Well upon reflection I am still not sure thats necessarily right either. It may not be CERTAIN that R-R identified and then "fixed" any mysterious root CAUSE (which had POSSIBLY imposed unsustainable loads upon the splined mounting boss area) OF the consequential cracking, however it would NOT be UNREASONABLE to assume that for all PRACTICAL purposes, they MINIMISED ( time will tell; remembering though, that "average" male life expectancy is only 76.5 years ) OR perhaps even totally DENIED, the opportunity for the arm to crack in the SAME previous fashion (IRRESPECTIVE of some vague, intangible "X" factor cause!) by making the arm THICKER IN THE MOUNTING BOSS AREA!. It would seem that R-R correctly addressed the EFFECT (ie "the breakage") of the CAUSE ( "X"?? ) rather than the "cause of the effect". Analyse this; When the "U" boat pens of Bloom and Voss (and others) were bombed (my since dec. uncle being a RAAF navigator) did Karl Doenitz order the construction of submarines with THICKER hulls to resist the ordnance OR did the German High Command ( like R-R, they were NOT stupid people!) build PENS with concrete walls/roofs THAT were several times THICKER. That is to say, THICKER than BEFORE!. SO, very THICK that the even so-called "Grand Slam" bombs often failed penetrate, although to be fair, they didnt have the todays technology for "pin-point" target aquisition. Crumbs..we arent talking "rocket (or bomb) science" here, but rather a simple case of rather obvious physics, combined with a modicum of BCS (Basic Common Sense). However, IF some kind of mysterious "problem" IS eventually found with Pitmam arm WASHERS, I DO hope it didnt result from people "marking" them with centre punches. |
John Dare
Grand Master
Username: jgdare
Post Number: 140
Registered: 12-2004
| | Posted on Monday, 31 January, 2005 - 08:02 pm: | |
Speaking of physics, Ive just recalled the story about the father who built a garden swing for his son, Kim. He duly selected a suitable tree with a healthy and sturdy branch from which he suspended ropes considered to be of ample sufficiency. The eager lad leapt into the robust wooden "plank" seat, whereupon the branch broke. A new thicker branch was selected but THIS time the ROPES snapped. Feverish calculations were made by the father and his academic, tweed coated, pipe smoking friends who muttered, mumbled, pondered and theorized. Elongation stress analysts arrived with instruments to test the ropes and horticulturalists descended like locusts upon any suitable trees which remained available. The tanglefooted village idiot, who happened to be stumbling along, came upon this vast assembly of higher intellect, whereupon he suggested a DOUBLING of the size of the last selected tree branch AND a tripling of the diameter of the currently deployed ropes. To the amazement of all (except the idiot) the swing THEN HELD!. Oh, JOY and WONDER, as Kim continued to enjoy the swing AND the CAUSE of the very problem, i.e his thrice daily visits to a well known fast food outlet. MORAL; IF you design anything strong enough, it will withstand any and all REASONABLE forces which are, by whatever unknown "X" factors (tsunamis excepted!) LIKELY to be delivered to, and imposed upon it in the NORMAL course of events. I believe and remain confident, that R-R have applied this simple "field" logic (along WITH lab. tests) to their redesigned, thicker and more visibly robust Pitman arms. |
John Dare
Grand Master
Username: jgdare
Post Number: 142
Registered: 12-2004
| | Posted on Monday, 31 January, 2005 - 10:17 pm: | |
But WAIT theres more!. Many readers, especially those who own (or have owned) EARLY production SC/S1 vehicles, will have probably experienced (or heard of) rear axle "1/2 shaft" failure where they would suddenly shear at the "inner" (differential) end. This was (and remains) generally accepted as being the result of the increased WEIGHT of the "new" body AND the increased power provided by the larger 4.9L engine as introduced in 1955. When Crewe first heard of this problem (as we know, not even R-R always "got it right" first time up!) does anyone seriously believe that they agonized over the weight of their latest design and apologised if not cursed, the designers for daring to produce a new more powerful engine to propel it?. Did they organize legions of learned, bearded boffins to devise means by which the combined factors of weight/power could be REDUCED so that less stress/torque loadings would be input to the axles?. Obviously they didnt. Did they terminate their driveline engineers and metallurgists for using steel that was suspected to be "too weak" or forged/ machined "too thin"? What about some "new" better/safer, torque values for any and all associated rear axle nuts (in case of "fretting") or even recalibration of the rear shock absorbers? Did they embark on a wild goose chase in the hope of identifying OTHER possible causative "X" factors, such as driver habits; if vehicle used for towing; passenger and boot/trunk loadings; regions where failures were most prominent; geographic (road surface) factors including volatile weather/temperature variations?. I doubt it. They simply made the axles STRONGER, and verily the "problem" thereby became part of recorded history. (Duh) |
Robert Wort
Prolific User
Username: robert_wort
Post Number: 86
Registered: 12-2004
| | Posted on Monday, 31 January, 2005 - 11:08 pm: | |
Hi John, I can relate to the rear axle problem with the SC1 as I had it myself on old Eleanor. It happened at 110,000 miles and I was informed by the mechanic of the day that if you were to check the 'rear transmission' oil every service for bubbles and change it if there appears to be any. You will ensure that the oil is kept at its correct viscosity and it should help to protect it in future ( although he gave no guarantees). I wasn't quite sure of the science of this, but I did that and when I finally parted with my dear old girl at 320,000 miles without further incident, I can only assume that he was right. Of course, I could have been just plain lucky. |
Patrick Lockyer.
Grand Master
Username: pat_lockyer
Post Number: 278
Registered: 9-2004
| | Posted on Tuesday, 01 February, 2005 - 05:38 am: | |
First if i may deal with the somewhat prolific piffle and rubbish postings by one of the above.
I shall ignore him and his somewhat strange manner as this is in my veiw is a very serious matter.
Pitman arm testing.
Shift work and they have done the business.
The arm after my cleaning and test i thought i had it clean enough,well they had to do it again.
It went for testing in a special room full of altroviolet lights with fluids,it passed with full colors.
Then many more tests as i said leave nothing unchecked,it was tested with sonic waves and every thing.
It passed and if it was for a plane they would use it apart from the weight.
So where are we now,shall i use it again you bet i will but with a different set up that i have completed today.
As Robert C confirmed this is one off the failing types,but no not the arm itself i must add.
It is my belief the modified arm is not getting over the prime cause of the failing.
It is my belief that the spline moves in the first instance due to the faults of the nut and washer.
even the new ones that arrived today are no good as they are.
By the way the spring washer had lost none of its tension.
The pix of the boss with the marks are from the spring washer.
It is my theory that the loading stress on the lower part of the boss from the angled lever from my original comments cause stage one fatique crack starting within the boss at the weakest point this is confirmed by the movement spline marks on the washer.
The splined angles are another factor with the forces within the boss.
Stage two, after time it is my belief that the crack gives up completly but the arm stays put untill a heavy loading such as parking at slow speed or hitting the kerb etc causeing total failure
looking as though the boss broke on the outside first.
Now have we agreement on this so far before i state and show my rectification on all types of arms.
 |
John Dare
Grand Master
Username: jgdare
Post Number: 143
Registered: 12-2004
| | Posted on Tuesday, 01 February, 2005 - 05:49 am: | |
Thank you Robert. May I assume that when you experienced the not uncommon early SC/S1 axle failure, your vehicle incorporated what you believed to be the original axles, one of which eventually fractured. If that was the case, are you able to recall and confirm, the nature (ie type of) actual repair/replacement as performed at the time? |
John Dare
Grand Master
Username: jgdare
Post Number: 144
Registered: 12-2004
| | Posted on Tuesday, 01 February, 2005 - 07:01 am: | |
The foregoing pictures of the Pitman arm which "they" (the Royal Aeronautical Laboratories at Farnborough??) are supposed to have "tested", show an old design, since superseded by another R-R factory issue part, with MORE metal in the boss area. Whatever the DEGREE of stresses and operational loadings (IRRESPECTIVE of their nature or origin!) the original washer "recess" design did not incorporate sufficient metal to ACCEPT such applied loads, HENCE the formation of a CRACK, in protest (and as CLEAR EVIDENCE) of that insufficiency. Note the foregoing concession in clear acknowledgement of that circumstance, Quote; "one fatigue crack starting within the boss area at the WEAKEST point". That WEAKNESS resulted (not suprisingly) in the evolution of a stronger arm which was significantly more robust at the mounting boss area. When you are next parked aside a prime mover/ "long haul" road tractor such as a "White" Freightliner, "Ford" Louisville or "Kenworth", simply glance (underneath the guard/fender) at the steering "drop" (Pitman) arm and note the relationship of the amount of metal surrounding (buttressing) the central mounting point (upon the steering box shaft) and the diameter of that shaft RELATIVE to the overall length of the arm. Take a mental note of those dimensional factors and then COMPARE them with the relationship of the dimensions as illustrated in the picture of the early design, DISCONTINUED (obsolete) R-R Pitman arm. NO "ROCKET (or "Sopwith" Camel) science" here, I am afraid to say. |
Patrick Lockyer.
Grand Master
Username: pat_lockyer
Post Number: 280
Registered: 9-2004
| | Posted on Tuesday, 01 February, 2005 - 09:30 am: | |
Rectification with a fixing mod is needed on all arms as the spring washer and nut are used on all arms without change.
This is the weak part.
You have been notified it is my opinion that the splines will fail through undetected movement by this nut washer weakness. |
David Gore
Moderator
Username: david_gore
Post Number: 385
Registered: 4-2003
| | Posted on Tuesday, 01 February, 2005 - 10:32 am: | |
John, with regard to your comments above; when Boeing had cracks in the wing structures of their aircraft did they strengthen them to make them more rigid or did they use other alternatives which did not affect the wing flex?
The answer is obvious to anyone who has ever flown in an aircraft and watched the wings - they do flex and in fact the flex is critical to prevent the wings falling off [a "strong" wing made according to John's reasoning above is guaranteed to fail in service within a very short time]. The engineering reasons are too detailed for a forum such as this.
Blanket assumptions such as those above are not appropriate in failure rectification as each case has to be resolved in terms of a wide range of factors and invariably some of these will conflict with each other - hence the wide-ranging and argumentative discussions that invariably occur between the experienced technicians, engineers and material specialists responsible for determining the most appropriate rectification procedure.
"Act in haste with pre-conceived ideas; Repent at leisure and hope that no injury has resulted from your folly". |
John Dare
Grand Master
Username: jgdare
Post Number: 145
Registered: 12-2004
| | Posted on Tuesday, 01 February, 2005 - 11:04 am: | |
UV/"Magnaflux" etc., all SOUNDS impressive, but what physical load/stress tests were applied and under what circumstances?. What was the "brief", for as D.Gore recently opined, the "answer" is often predicated upon the composition of the question. Specifically; HOW, may I ask, was the "tested" Pitman arm and steering box shaft, "jury" rigged (in a "bench" type environment) to simulate and record the expanding pressure upon the boss, as exerted BY the taper when the nut was correctly tensioned?. I suspect that for the sake of credibility, some readers might also be interested to know WHO actually performed the "test". Given that you vigorously complained of a cost of 400+ pounds for a modified, thicker, replacement arm, you may appreciate my suprise that you have allegedly commissioned (at your expense) comprehensive and conclusive "factory/lab." type tests which could potentially cost thousands of pounds, being tests not LIKELY to be commercially available from a nearby provincial "aircraft hanger" type facility. Even if they were, I doubt that such tests would be routinely available and completed within the time frame of a few days and at a realistic, or even acceptable cost, which at the very least, would certainly eclipse the cost of a Shepherds Pie down at "The Red Lion". |
John Dare
Grand Master
Username: jgdare
Post Number: 146
Registered: 12-2004
| | Posted on Tuesday, 01 February, 2005 - 11:58 am: | |
Yes, I am aware that aircraft wings (fixed or rotary) must be able to "flex", UP TO A POINT. I mean you dont see them flapping like those of seagulls and if you ever did, then it might be time to reflect upon your will and loved ones. Similarly a Pitman arm (like the Harbour bridge) would also possess an ability to "bend/flex" etc (at some points and TO SOME EXTENT) but NOT beyond certain calculated limits, breach of which, would typically precipitate failure or collapse. There are U.S based mnfrs. of custom-made Pitman arms, designed for EXTREME 4WD applications, not likely to be encountered in normal "off road" conditions and when I last viewed them they appeared to be of larger (not reduced) overall dimension. In any event, it will probably be all over (within the next 24 hours or so) as certain evidence will be examined in detail, to reveal a frightening and undeniable reality. At that time, readers might THEN like to reflect upon my previous comments regarding liability, which in the event of a fatality, could lead to the question of culpability. More to follow. |
David Gore
Moderator
Username: david_gore
Post Number: 387
Registered: 4-2003
| | Posted on Tuesday, 01 February, 2005 - 03:42 pm: | |
John, this is not a Court of Law where legal practitioners pontificate and obfuscate to try and confuse everyone by sheer volume and minute points of difference. The download time for this thread is now excessive for those on dial-up connections and I request all future posts from everyone be brief, concise and to the point. |
Robert Chapman
Grand Master
Username: shadow
Post Number: 164
Registered: 5-2003
| | Posted on Tuesday, 01 February, 2005 - 08:45 pm: | |
Hi Patrick,
Do I understand correctly,you have come to your conclusion.That in your opinion it is the nut that causes the arm to come loose on the splines(unseen) and that eventually causes the arm to break.
Could you explain what in your opinion happens,since previously you said that the nut was not loose and there was no evidence that the boss had worked its way up the splines,yet your nut markings did not line up.
I agree this forum is not a court of Law but I believe this subject has the potentail(especially for professional motor engineers) to very easily end up in one. |
Patrick Lockyer.
Grand Master
Username: pat_lockyer
Post Number: 284
Registered: 9-2004
| | Posted on Wednesday, 02 February, 2005 - 05:06 am: | |
Spline movement confirmed by the marks on the spring washer,it is in my opinion that the bearing surface of the spring washer nut is not enough for the torque applied.
After examination of the arm top splined face it has over a time compressed and is due to the high torque figure upon the spring washer face with the nut face that is totaly inadequate.
If left for a long period the lower boss splines
move causing excess stress loading to the point of tension and then to crack at the weakest point, with stage one as above.
To rectifiy the problem first mill the boss face till the washer sits flat.
The washer is thicker wider with a smaller hole ,more surface contact area,it is milled to size,far more sturdy than the spring washer Pix.
The new nut arrived but as you can see the bearing face is just not up to the job,the nut face has to be milled as well to get the most surface area.pix
After the required checking and milling the arm is offered up and assembled to make sure the nut is indeed fully on the threaded shaft.
Proceed to use WURTH a German product[better than Loctite in my opinion]this has to be applied to the splines,shaft threads,washer and nut.
Now the torque,no not 200ft lbs but 150ft lbs pix
Job Done!! |
John Dare
Grand Master
Username: jgdare
Post Number: 148
Registered: 12-2004
| | Posted on Wednesday, 02 February, 2005 - 07:50 am: | |
Lines 6/7 of the foregoing post at 6;06am state "and then to crack at the weakest point". Whatever the source or origin of an applied force, any item will eventually fail (typically at its WEAKEST point) once a certain critical threshold has been breached. THAT is why R-R increased the mounting boss area of the ONE type of Pitman arm that was prone to failure (AT its weakest point!) by WHATEVER cause, perceived or real and IF the latter, then PROVEN to be so by a RECOGNIZED independent eng. test laboratory. To date there have been no recorded failures of the later, modified, stronger arm, NOR is there any reasonable expectation that it will fail (in the same manner and location) given that due to their earlier experience, R-Rs sophisticated eng.lab WOULD have performed searching and exhaustive tests (load/stress/fatigue etc) PRIOR to release of such a modified SAFETY, "life or death" component. Failure to DO so would NOT have been an option, given the OBVIOUS implications in respect of liability. Despite this, veiled "wait and see" suggestions have been variously advanced, predicting that even the modified arm "might" ALSO fail at some future time. Since the issue of a "Court of Law" has been raised, may I ask if anyone IS effectively suggesting (in ANY way whatsoever) that the modified arm was NOT tested by R-R, OR was tested, but perhaps NOT in a proper or conclusive manner. If neither are being suggested (OR even remotely IMPLIED) then I will reasonably conclude that there is an ACCEPTANCE (however reluctant) that R-R DID comprehensively and conclusively TEST the arm and that as a consequence, said arm is therefore not LIKELY to fail (as did the former) due to its INCREASED mounting boss area dimension. Accordingly, if the arm PASSED stringent R-R tests, then the presence of the additional support/buttressing metal surrounding the mounting boss area of the arm as modified, will have clearly been seen as providing the MEANS of PREVENTING any fracture, IRRESPECTIVE of the origin or nature of any applied forces considered to be causative. |
David Gore
Moderator
Username: david_gore
Post Number: 388
Registered: 4-2003
| | Posted on Wednesday, 02 February, 2005 - 10:26 am: | |
Too many assumptions - not enough facts and too much speculation about what R-R did or did not do; too many repetitive word from previous posts and no consideration of the most important point involved i.e.
It is possible that fixing the APPARENT cause of the initial failures will allow less aggressive secondary causes [which may also have contributed to the initial failures] to become active and cause unexpected problems later in the life of the vehicle - I do not believe for one minute that R-R would have conducted the field testing necessary over several decades to reveal the problems found by Patrick and/or the probability of future failure from secondary causes - the history of engineering has too many instances of service failures that were never predicted by extensive laboratory testing.
This is a fundamental lesson all applied scientists and engineers are given very early in their education and one which we ignore at our peril - despite all the information and technology available to us; we are not and never will be infallible [unlike our legal counterparts who profess we are when there is money to be made as a consequence of this fundamental lesson - it is an interesting fact that you have no comeback on a lawyer who loses a case as a consequence of their relative lack of knowledge/inexperience in comparison to their opposition]. |
Robert Chapman
Grand Master
Username: shadow
Post Number: 165
Registered: 5-2003
| | Posted on Wednesday, 02 February, 2005 - 09:18 pm: | |
I believe there is the potential for a very dangerous precedent to be set here ,the proposition being advocated is that it is ok to machine safety critical steering parts and reduce manufactuers tightening torques and this will prevent failure.This could lure owners into a false sense of security and to the assumption that the new arm is not needed.
Patrick L,
1)You have reduced the thickness of the nut( no matter by how little)and therefore reduced the total contact area of the threads from a nut that you previously said was "to thin".
2)You have reduced the thickness of the boss on the arm,an arm you previously said had "a weak point" and recommend refitting it.
3)You removed material from an arm of a particular design known to fail,a part improved by RR by increasing the material around the boss.
4)You have recommended reducing the clamping(tightening torque) tension on the splined taper connection by approximatly 25%.Interesting that RR during there examination of this falure and redesign of the arm did not find it necessary to change either the nut or the washer arrangement.
5) You have told us that your re-tensioning procedure had revealed that the centre pop marks did not line up and this told you that something was going on,you have suggested that this was to do with the nut and washer.
If you execpt this procedure as accurate I would suggest it much more likely given the history of this arm that in fact the boss was/had expanded therefore allowing the splines to go deeper into mesh, in other words the boss working it way up the shaft.
This then should be taken as a serious warning sign as the depth of engagement at a given clamping force should remain constant any increase in the depth of engagement could indicate expansion of the boss.
Personally I should not care who had carried out what tests on the arm after seeing the incipient cracks in that arm ,I would certainly not weaken it further by removing more material and then refit it,possibly endangering not only my life but also other road users and all for the sake of 400 pounds.
I certainly agree that there has been to much assumption and not enough facts,the assumption has been that the fault lies with the nut and washer contrary to RR findings and actions and that if we machine more material from the arm and re-tension the nut every two years not only will this stop failure of the original arm but also the new arm!and the only known fact is this arm can break at ANY time without notice,so why take the risk .As RT pointed out at the very start,souldn't be changing them all now,reasoning that makes more sense as every day goes by. |
John Dare
Grand Master
Username: jgdare
Post Number: 149
Registered: 12-2004
| | Posted on Thursday, 03 February, 2005 - 01:10 am: | |
Thank you Robert. In relation to your final para. I agree with you, whereby you acknowledge the existence of what has been perceived in some areas as, "too much assumption and not enough facts", also noting at review, the further suggestion that there has been, "too much speculation". In relation to the former, it is interesting to note that submissions posted on Feb 1st,2nd, incorporate statements such as, "it is my opinion", "my belief" and "my theory" etc., on approx. SIX occasions, thereby prefacing what can only lead to ASSUMPTIONS. As such, and in the absence of any endorsement or validation from an independent recognized engineering authority (ideally R-R Motors!) FACTS and/ or factual CONCLUSIONS must of necessity be denied. In regard to the suggestion of "too much speculation", I note within the same post (with ADDED emphasis) quote; "it is possible that fixing the APPARENT cause of the initial failures will...", the two words "possible" and "apparent" in themselves appearing to invite a notion of SPECULATION. Turning now to, "too many repetitive words from previous posts". I agree yet again, but rather than allow ones gentle sensibilities to be affected merely by REPITITION (see words such as "RUBBISH" / "FILE DUMP" etc) I would be more concerned with DESCRIPTIVE words such as FRAUD, which, if misdirected and applied within a personal context, may well have implications not anticipated by author or publisher. |
Patrick Lockyer.
Grand Master
Username: pat_lockyer
Post Number: 287
Registered: 9-2004
| | Posted on Thursday, 03 February, 2005 - 05:25 am: | |
Robert C,
reply No1.
I have left a very important detail as i thought you would have picked it up being a engineer.
Look at the splines in your broken boss Compare the to mine.
I cannot under stand why you have missed how far the shaft splines have rissen in the boss over a long period and still more to go!
What does this tell you.
Yes Yes avoid "Space"Nothing.So no contact to the face boss part of where the 200ft lbs torque with the feeble washer and nut in its supplied state.
And to add the position of the lever to boss.
As to the amount of milling to the nut and boss it is of no importance due to the large milled thicker washer.
As to the redused torque of the nut it is more than satisfactory due to the modified set up.
No2.The boss thickness is reduced a little to tidy up the face and we are talking of the compressed face.
The milled thicker flat washer with far more surface area spreads the torque loading and it will not of course compress as with the old spring washer set up causing movment.
No3 Putting more metal round the boss in my opinon will not stop spline movment with the old spring washer and feeble nut as is supplied.
No4 Try to under stand that less torque with more bearing area through the flat washer and modified nut is a far better set up,no compression.
Of course with the modern Wurth locking system product.
This is modern progress.
No5.Robert you really have to look at your pix and compare the splines with my pix.
It will tell you that the crack started at the top inner spline area.
As for my arm as i stated it had not moved up the shaft spline,i assure you that when removed by the hydralic puller there was the bang crack, what does that tell you!
Robert the testing was carried out with no expence spared,it passed 100%
As for the marks that you think are cracks in the top face they are as i have said before from the "split" spring washer marks.
I shall ignore the rambling posts and hope every one else does.
(Message edited by david_gore on February 03, 2005) |
Patrick Lockyer.
Grand Master
Username: pat_lockyer
Post Number: 288
Registered: 9-2004
| | Posted on Thursday, 03 February, 2005 - 07:14 am: | |
Robert just found this pix before the arm was removed with the hydralic puller.
Can't see the splined shaft can you.
What ever was going on with your dummy shaft exercise with the three arms that were showing cracks but not broke.
Did you not notice the washer spline marks indicating movement of the top face of Boss.
Have you still one of the arms that is showing cracks but not broke?
Just fitting the modified arm in my veiw will have stated probs later in its life.
DANGER.
movement boss face. |
Robert Wort
Prolific User
Username: robert_wort
Post Number: 90
Registered: 12-2004
| | Posted on Thursday, 03 February, 2005 - 02:13 pm: | |
I think the last time someone asked
for opinions on design it was about an animal..... the platypus was created!!!!!!!! This is a joke and it is intended as such. The same way that the word Fraud was. There are many serious issues in the discussions above but some comments are taken too seriously. let's lighten up a bit eh?
|
whunter
Grand Master
Username: whunter
Post Number: 140
Registered: 10-2003
| | Posted on Thursday, 03 February, 2005 - 02:57 pm: | |
Hello David Gore
The nut torque does change, when the arm begins to fail.
Patrick has inverted cause and effect, possibly without being aware of it.
Effect = torque loss on nut.
Cause = expansion of arm collar.
This problem is not specific to R-R/B vehicles.
I have seen it hundreds of times, generally off road vehicles worked beyond structural limits.
The collar of the arm stretches wider, allowing the collar to rise up the spline shaft = relieving pressure upon the nut, next the spline shaft collar cracks.
The correct test is extreme GD&T inspection of the arm collar bore and spline dimensions, only the supplier or OEM will have enough GD&T detail to interpret the results.
Patrick Lockyer is a well meaning hobbyist; but this topic needs to end.
The assertions, claims and statements made here are in several cases potentially lethal.
The insinuation that Rolls-Royce engineers are inept, incompetent or stupid on this safety issue is wrong and offensive.
My sincere hope is that this thread is removed, as I would rather not be summoned to testify in court, which is very possible today. |
Patrick Lockyer.
Grand Master
Username: pat_lockyer
Post Number: 291
Registered: 9-2004
| | Posted on Thursday, 03 February, 2005 - 03:52 pm: | |
W.Hunter.
If Robert can confirm his misunderstanding of the issue and exccept my findings that i have stated from the start im sure it would help.
The ground work has been done by myself.
Prehaps the issue will be looked into and recalls on all arms done.
With new 21st centenary technics applied.
As for the rambling parret just ignore it,its just piffle for the file dump.
|
John Dare
Grand Master
Username: jgdare
Post Number: 152
Registered: 12-2004
| | Posted on Thursday, 03 February, 2005 - 04:59 pm: | |
Thank you W.Hunter for your professional, compelling and decisive summation which expounds the principle of "cause and effect", to which I had previously alluded at 7;32 on Jan. 31st. As a qualified ASE Master mechanic you have not suprisingly, articulated it well, hopefully rendering it understandable to all, even those who you note, appear to have unwittingly "reversed" the application of the age old principle. Indeed, an interesting contrast to the "findings" (??) of others. I DO especially like the part; "problem (ie the Pitman arm) is NOT specific to R-R/B vehicles" AND.. "Ive seen it hundreds of times... the collar (boss) of the arm stretches wider etc ". I suspect some will NOW attempt to suggest that (and other points you have advanced) is EXACTLY what THEY were/are saying ?. As an aside, I see that there are some current pics. of what appear to be tie rod/track rod ends (?) under your old "Hydraulic Fluid seminar" thread. Not sure of the RELEVANCE (which we were recently asked to observe) so I guess we have to "Guess" ? |
Patrick Lockyer.
Grand Master
Username: pat_lockyer
Post Number: 292
Registered: 9-2004
| | Posted on Thursday, 03 February, 2005 - 05:43 pm: | |
W Hunter.
I would to bring your attention to one finding with your boss riseing up the taper spline theory that would only happen if the boss was letting go.If it was doing just that the force to remove it would not be needing the hydralic puller or if it was it would not go with the crack bang as mine did.
Foget the rambling piffle above from dare i say. |
RROCA Web Site Administrator
Moderator
Username: admin
Post Number: 26
Registered: 10-2002
| | Posted on Thursday, 03 February, 2005 - 09:04 pm: | |
This thread has been closed.
It's too large, too acrimonious and now has the lowest signal-to-noise ratio ever seen on this Forum.
All users are hereby on notice to remain polite, tolerant, concise, coherent, intelligible and on topic, or risk having their posting deleted or account disabled.
Play nice, boys! |