| Author | Message | ||
     Bill Coburn Grand Master Username: bill_coburn Post Number: 274 Registered: 4-2003 |
As everyone knows there were two plunger seals used on these master cylinders. The changeover was during the S1 (sic) production run. I am in the process of replacing these same seals on a Cloud III and as promised both seals come in the kits. Unfortunately there is no explanation as to which is the correct seal. The original service bulletin tells me that the new seal has a dot of blue paint on it. Seems that since that was issued they have run out of blue paint! I don't really trust the people who did the job before so matching the new seals to those which were fitted does not inspire my confidence. Any help please. | ||
| Robert Chapman Grand Master Username: shadow Post Number: 109 Registered: 5-2003 |
Bill, I will send you a picture in the morning by email. If you have any trouble bleeding the brakes after fitting the cylinder, try having the wheels balanced. | ||
| Bill Coburn Grand Master Username: bill_coburn Post Number: 276 Registered: 4-2003 |
I have found out that it is the smaller of the two plunger seals you use on the Cloud III and the II and most of the one's I believe. I worried that I may have been suffering from Glenlivettitis when I found the original service bulletin issued circa 1957 announcing the change in seals and assuring me that the later one was identified by a touch of blue paint. Well I have concluded that the paint pot has run dry after 47 years 'cause there was nary a drop of paint. I did actually fit the early seal initially and the piston was very noticeably firmer and therein lies the reason for the change my advisers (not one of you wheel balancing lot!) told me. The piston took so long to get back to square one it was not able to recharge for the next stroke! One other interesting thing about this much used Cloud three is that the trapeze linkages are quite worn including the top pin that the thing hangs on. Worse, the hole on the chassis plate that the top pin sits in has also elongated a little and the cumulative lost motion which has to be taken up with the lower smaller master cylinder plunger calls for a big adjustment down below. Next stop, methinks is going to be a lot of work. (Message edited by admin on January 01, 2006) | ||
| Donald Maloid New User Username: prodmgr Post Number: 2 Registered: 9-2007 |
Hi Guys, My Bentley S2 braking is less than adeqate for safety. I've rebuilt both master cylinders, replaced all 5 rubber brake lines, and bleed the system countless times. I'm not sure of the brake servo though it appears to look fine I guess. When I step on the brake, very little happens though I hear light braking action so I step a little harder and it bearly has enough brake to stop. what could be wrong? please help! | ||
| Paul Yorke Frequent User Username: paul_yorke Post Number: 75 Registered: 6-2006 |
Hi Donald, when you say the servo 'looks fine' - what do you mean? The usual problem with them is that oil from the gearbox leaks inside them and contaminates the servo clutch plate. The plate will then take on a dark , shiny, polished, look. (with very little 'grip') There will probably be oil inside, but sometimes a very minimal amount. The extension that fits on the gearbox which the servo mounts on has a small tube that should let escaped oil drip through, so if this is wet - the servo is probably contaminated. Wheel-free the car on a ramp or jack up the car safely with the rear wheels off the ground With the wheels being driven, Lay underneath so you can see the servo, have somebody press the brake pedal slowly down, the servo should whip around ( about 1/4 turn ) fairly quickly and stop the rear wheels. Revving the engine will make the brakes come on harder. If the servo turns but it doesn't stop the rear wheels, use a lever on the master cylinders as though bleeding them and see if the rear wheel stop then. | ||
| Bill Coburn Moderator Username: bill_coburn Post Number: 923 Registered: 4-2003 |
Donald/ Can we have an assurance that you are getting pressure from the master cylinders? Put a lever in the trapeze to the rear of the master cylinders and push forward. The master cylinder plungers should move a short distance and then stop as they hold the shoes hard against the drums.Hold the pressure on for a couple of minutes and I mean pressure - use your foot on the lever to give it weight! If the cylinders are faulty and they are getting to be this way with age the pressure will leak away and your lever will slowly move forward! I am suprised that you would do the master cylinders and NOT the servo. The linings even without oil on them tend to glaze as Paul says which can be corrected by judicious rubbing down on fine sand paper on a sheet of glass. If oil is getting through to the servo plate the seal will need to be replaced. Use a double lip one. If the shaft is scored from the old seal belt a stainless steel ready-sleeve over it and it will last forever. The driven plate should have radial grooves cut it to clean the lining. If not cut some in. If the driven plate is scored or unevenly worn it can be trued up with a light skim on a machine used to surface grind flywheels! Lastly the drain tube Paul refers to. This originally was peened inside the body of the extension. They sometime get knocked off and replaced with a bit of brake tube which is OK except thet the level of the end in the housing has to be no higher that the inside surface other wise any oil that gets in there will be dammed up. | ||
| Paul Yorke Frequent User Username: paul_yorke Post Number: 76 Registered: 6-2006 |
Bill . . . "I am surprised that you would do the master cylinders and NOT the servo." That's a bit harsh LOL.  Maybe he's not used to the R-R brake servos's vodoo magic ways and it's shortcomings! Question is: Should he try having the wheels balanced first ? | ||
| Bill Coburn Moderator Username: bill_coburn Post Number: 924 Registered: 4-2003 |
My dear Paul/ I don't know you well enough to know whether you are playing with me. The wheel balance is a fair indicator! Actually I have just this minute stopped talking about this very matter to Richard Treacy in Switzerland whom I have known for nearly thirty years - he used to be a nearby resident in Canberra. As you I think know, I spend a fair amount of effort on producing Tee One Topics which is apparently fairly well accepted around the traps and when somebody asks a question about balancing the wheels when one has just exhausted the subject in the last issue it does tend to loosen the bowels slightly! I am no expert and my amateur status is fully documented but there is a coterie of owners who come onto this forum with lines such as 'I was driving my off-peuce Silver Mist with Cobra skin upholstery and silver plated wheel nuts and it stopped what do you think is the problem. OK hyperbole aside I fervently hope that the information that the likes of you and maybe myself provide would be thought about before leaping in with a request for assistance. As to the current enquiry, in the last 18 months I have had more troubles with the post55 braking systems than most mechanics would have in a life time. And almost all of it is related to age. These cars are bloody ancient and should by rights be crunched to make more Toyotas but fools like us persevere and the use by date gets forgoten. No problem except that the approach has to be different. No longer do we have to pay homage to the trite little service lists A B C etc, they are simply a framework. Joints now have to be lubricated or dismantled and checked that most owners and many of the current service people don't even know they exist. You may have noticed the wear report I gave on the fulcrum pin mounts for the post55 brake trapeze. I just wonder how many people have thought about that one - I bet not anyone in the Factory! God I prattle on! But seriously, Richard and I are in the process of setting up a separate web site to incorporate a very comprehensive library purely technical to start with. Included will be not only the standard service routines but new ultra-service routines for the very old cars. Most readers (assuming there are some) will not have a schmik about these latter problems but I have hopes they will go along to people such as your goodself and say ' This silly old fart in Canberra thinks my wigwam should be checked and regreased - what do you think?'. That will give you hopefully an opportunity to say 'rubbish - quite unecessary' or ' probably not a bad idea'. That way you avoid the impression that you are trying to drum up business by telling all owners that they should get their wigwam greased - if you follow me! A good friend of mine in this country with a successful repair business for the marque tells me that he frequently tells owners that they should replace their brake hoses. 'But they look alright' is the frequent response!!! Anyway I'll stop. Thank you for your efforts they are appreciated. Cheers | ||
| Paul Yorke Frequent User Username: paul_yorke Post Number: 77 Registered: 6-2006 |
Hi Bill, Yes, I was playing with you!! I had flipped to the top of this topic and saw the wheel balancing comment there . . . which is where I pulled it from. I assumed Robert C was joking to! Maybe not. Indeed brake hoses and hardening of the arteries are silent killers which people tend to ignore until they have a major problem! To answer your question about Wigwam greasing, I always do my clients at a matter of course, even between services if they pop in, along with adjusting the fou-fou valve. It is NEVER a waste to grease in my opinion. I think balancing of the Wigwam can be left to 12000 miles regardless of time! Seriously though everyone. Bill is right to ignore the 'lower' service schedules. Lubricate and Grease everything, at every opportunity. Change oils more frequently than is recommended. Write dates on things like filters and tag things like brake fluid changes etc. Time goes by so fast without realising it. Keep up the good work Bill! | ||
| Peter Colwell Frequent User Username: peter_colwell Post Number: 55 Registered: 3-2005 |
Its unfortunate that the people who were brought up in the era when all manner of wigwams needed greasing, routinely, - are dying out. I have been known to attack squeaky Motel doors with WD40, for an overnight stay, so all my wigwams are well greased. However my newest car from the Fatherland, does not even have an engine dipstick. One stops on level ground, and presses a button, just like my 1957 Silver Cloud, except that all I get now is a 'oil level satisfactory' message. I don't know what happens if it just about to become unsatisfactory, at the start of a 1000 mile journey.... | ||
| Paul Yorke Frequent User Username: paul_yorke Post Number: 78 Registered: 6-2006 |
PC, Don't fret! I'm sure it will let you know - in no uncertain terms! Probably whilst it simultaneously dials the factory to tell them about the fault, and downloads a litre of synthetic oil as you pass a Starbucks Hotspot Whilst talking of new technology and improvements - when was the last time somebody had a water hose actually burst? I had to replace *another* burst hose on a Seraph having a failure to proceed moment on Friday. What is that about? To add insult to injury , one of the hoses was about £70! | ||
| Bill Coburn Moderator Username: bill_coburn Post Number: 925 Registered: 4-2003 |
For All. For the record Robert Chapman was having a go at me at the time - it was inspired by an old contributor who would drop the most extraordinary suggestion into a repair debate and we were never quite sure whether he was serious or suffering from an overdose of Balveney! Fascinating Paul about a burst hose on a Seraph. I wake up screaming occasionally having dreamt of such an event. Years ago on a back country road I was tootling along in an old S2 at about 90 mph - a respectable speed in most peoples' minds and was overtaken by a then fairly 'new' Silver Shadow endeavouring to break through the sound barrier. The S2 had barely recovered from the lurch generated by the slip stream and my eyes had just focussed when the latter were treated to a one off lifetime view. I would loosely describe it as an exploding Shadow! I now describe it as the computer graphics now used to indicate some enormous space ship entering hyper-drive - whatever that is. Steam and smoke belched around the car, the rear end lifted somewhat and the rear wheels seemed to be skidding from side to side. Much standing on the stoppers and we eventually approached the wreck from the rear with much incredulity. The engine had not only seized it had 'broken'. There were visible cracks in the block, belts had broken and fuel dribbled from mysterious places around the top. The top hose had burst probably some distance before the car passed us and the driver thought the drop off in performance was probably bad fuel so was giving it the gun as he described it to 'clear' the problem. I often wonder what happened to that car - the rear vision mirror was still in good nick! |
