Final drive crossmember, small subfra... Log Out | Topics | Search
Moderators | Register | Edit Profile

Australian RR Forums » Miscellaneous » Final drive crossmember, small subframe and boot floor strengthening « Previous Next »

Author Message
Top of pagePrevious messageNext messageBottom of page Link to this message

Richard Treacy
Grand Master
Username: richard_treacy

Post Number: 573
Registered: 4-2003
Posted on Saturday, 12 February, 2005 - 07:17 am:   Edit PostDelete PostView Post/Check IP

I invite contributions and photos of individual experiences on the final drive failure issue before I finalise an article on this matter.

Many thanks in advance,

RT.
Top of pagePrevious messageNext messageBottom of page Link to this message

Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 323
Registered: 9-2004
Posted on Friday, 25 February, 2005 - 08:53 am:   Edit PostDelete PostView Post/Check IP

To-day the job of the rear crossmember has started.
Had to take the LPG tank out first.
Leaving the car on its wheels on the hoist but with a support under the diff the crossmember was removed.
The rubber mounts were removed and this in my opinon is some of the start of the probs.
As the bushes wear they cause lateral excess movement with the crossmember.
If left unrepaired metal fatique through stress weak points develop with the weak crossmember and floor mountings stress points.
Spot welds round the bolt area dont help.
On the crossmember n/s mount bolt fixing one had started to lift up confirming a weakness.
The mods i will make and fit starting tomorrow.
More to come as the work is carried out.
Pix on the mounts and boot floor.



Top of pagePrevious messageNext messageBottom of page Link to this message

Richard Treacy
Grand Master
Username: richard_treacy

Post Number: 565
Registered: 4-2003
Posted on Friday, 25 February, 2005 - 08:25 pm:   Edit PostDelete PostView Post/Check IP

Thanks, Pat.

I look forward to more snaps.

Has the crossmember been previously modified by the way (with through-bolts attaching the mount to the top and the bottom of the crossmember) ?

Could you do me a favour and let me know the offset for the Z-bracket as I forgot to record it ? The details have aroused quite some interest, and I feel silly not having this basic measurement
.
Thanks, and

Regards,

Richard.

ps it's good to see that you and others are taking this matter seriously and taking action.
Top of pagePrevious messageNext messageBottom of page Link to this message

Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 324
Registered: 9-2004
Posted on Saturday, 26 February, 2005 - 06:17 am:   Edit PostDelete PostView Post/Check IP

To-day i fabricated the plates for locating the spacers and strengthening the lower crossmember section.
The large 2" holes have to be flatened so the new new plate will sit flat on the crossmember.
The threads are drilled out in the old mounting captive nuts and the lower section is then drilled useing the top hole as the guide.
Once the lower holes are drilled they have to be opened up for size for an interference fit with the spacers.
The two spacers must be made to stand just a little proud so that the plate compresses them when all clamped up with the mounts.
I was not happy with just the two bolts clamping the plates to crossmember so have migged them in place with short welds.

The first pix is of one spacer tube fitted and the
new plate RT that is welded and clamped after the other spacer is fitted.



The next pix is showing the spacers with the plate welded to the lower section.
Note at the end, the mounting plate with the four threaded holes is now welded in place externaly,this is for the harmonic dampers.



Last pix is just to show the diff asembly support.



Top of pagePrevious messageNext messageBottom of page Link to this message

Richard Treacy
Grand Master
Username: richard_treacy

Post Number: 566
Registered: 4-2003
Posted on Saturday, 26 February, 2005 - 06:51 am:   Edit PostDelete PostView Post/Check IP

Pat,

This is brilliant work.

The original factory lower crossmember mod indeed did not use just two bolts on the lower crossmember mount, but had two additional countersunk setscrews to keep the new lower plates flat and to spread the loads (see my earlier pictures). I am sure that your MIG welding will spread the load better than bolting, but a metallurgist or two may care to comment. Given the flaws which needed MIG repairs just recently on our '72 car's lower crossmember, despite having been modified anonymously by R-R in the late 1970s, you have pipped everyone at the post.

Let's watch this space. I hope I may use the pictures with due acknowledgement to you, and shall hold back a few days on submitting a Praeclarvm aricle accordingly. I am most interested soon to see your own solutions to the subframe (Z-bracket I named our fix) and boot floor reinforcement. Maybe ours will prove a bit rough-and-ready by comparison.

Useful to all would be details on any positive signs of imminent failure. The boot floor piece which separated on ours highlights the limitations of spot welds, and your previous pictures confirm this. I would personally be selfishly glad to hear that you have avoided a near catastrophe as our car suffered (thankfully it was only money in our case).

RT.
Top of pagePrevious messageNext messageBottom of page Link to this message

David Gore
Moderator
Username: david_gore

Post Number: 396
Registered: 4-2003
Posted on Saturday, 26 February, 2005 - 08:20 am:   Edit PostDelete PostView Post/Check IP

Provided the welds have full penetration with adequate heat input; it is most unlikely these will be potential sources of future problems.
Top of pagePrevious messageNext messageBottom of page Link to this message

Bill Coburn
Grand Master
Username: bill_coburn

Post Number: 343
Registered: 4-2003
Posted on Saturday, 26 February, 2005 - 11:36 am:   Edit PostDelete PostView Post/Check IP

Richard relax. The cut offis stll yonks away and when David gets burried in rally stuff we will be among the last to be inserted.
Top of pagePrevious messageNext messageBottom of page Link to this message

Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 325
Registered: 9-2004
Posted on Monday, 28 February, 2005 - 04:28 am:   Edit PostDelete PostView Post/Check IP

Now the crossmember is completed the task of checking the body mounting structure,good news both sides are ok so i will be leaving as is.
A good look into the floor mounts and i am not happy at all with the feeble inner spacer locating on the boot floor section.
As this takes all the loading if the bolt becomes slighty loose through section fatique etc the top and bottom sections with spacer will pull out with the results of the whole diff assembly dropping with disastrous results as RT has brought this to attention after the Bentley suffered from this.
The next job is to make some renforced plates for the boot.
The one important job on all Shadows etc is to check the boot floor mounting bolt for tightness as the nut is without any locking device,
I would recomend checking the silent block mounts with the rear wheels off if there is any strange noises within the rear end area.
More to follow as the repairs take shape.



Top of pagePrevious messageNext messageBottom of page Link to this message

Richard Treacy
Grand Master
Username: richard_treacy

Post Number: 569
Registered: 4-2003
Posted on Monday, 28 February, 2005 - 04:49 am:   Edit PostDelete PostView Post/Check IP

Thanks again, Pat.

The tightness of the main bolt is an impotant issue which you have raised.

You will notice from the pictures in the other thread, on our car there is now a Nylock locknut on the main mounting bolt for the very reason you cite. A Nyloc nut is fine as it is a low-temperature application.

RT.

ps do I see flaring of the subframe in your picture due to the distance piece ? If so, by the way that's why we fitted the Z-bracket. I referred to a mismatch between the small-diameter distance piece and the subframe, and also the boot floor. Your idea of a new, far larger diameter distance piece seems to be an excellent alternative.

It looks to me like you caught this just before it would have failed.
Top of pagePrevious messageNext messageBottom of page Link to this message

Richard Treacy
Grand Master
Username: richard_treacy

Post Number: 570
Registered: 4-2003
Posted on Monday, 28 February, 2005 - 05:22 am:   Edit PostDelete PostView Post/Check IP

To avoid confusion, the inner spacer and distance piece are one and the same component.
Top of pagePrevious messageNext messageBottom of page Link to this message

Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 328
Registered: 9-2004
Posted on Tuesday, 01 March, 2005 - 06:01 am:   Edit PostDelete PostView Post/Check IP

Another day of progress, useing 14g sheet metal 6"+6"i made the recess and welded a heavy flat washer.
This is the most important part as the bolt and all the load is carried on the plate recess.
The washer is of larger diameter than what is used originally so the bearing surface circle has to be
enlarged.
Pix of recess and heavy type flat washer.




Pix of completed plate



The O/s plate will be more or less a mirror image
of this one.
When the boot floor plates are bolted up with the crossmember assembly i will put some type of fixings for locating them if the bolts are removed
at any time.
Going back to the damper bracket that i welded in place,i was not happy with the reliance on welds alone so have drilled the centre and fitted one nut and bolt with washers on each.
Pix crossmember fitted up with mounts and dampers.

Top of pagePrevious messageNext messageBottom of page Link to this message

Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 330
Registered: 9-2004
Posted on Wednesday, 02 March, 2005 - 04:41 am:   Edit PostDelete PostView Post/Check IP

Hummmm! Mirror image,well that was not to be, the fuel tank mountings come close and the recess is stepped so have made a different shape plate today.
pix o/s boot floor mount.



The n/s was completed first with four fixings and then the o/s but with only three.
This i preffered than welding in place as the zink coating of the body would be burnt off,a source of corrosion in future years.
The main stress loading is on the n/s due to the directional torque of the drive.
The bolts were put in place and the crossmember assembly was bolted up with the single washer idea as Richard T suggested due to the drive shafts being more in line, be it just a little also i was able to use the stepped original bolts with Nylock lock nuts.
All went ok and the lpg tank was refitted and the car tested with a clean bill of health.
How lucky to catch the job in time before the failings occured,it would have been just a matter of time.
The z plate was not needed in this case.
Pix of the n/s boot floor mount.


I will do some checks in the near future of other stress loaded points as these cars are getting on a bit,dont want to be an alarmist though.
Top of pagePrevious messageNext messageBottom of page Link to this message

Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 331
Registered: 9-2004
Posted on Wednesday, 02 March, 2005 - 09:00 am:   Edit PostDelete PostView Post/Check IP

two more pix.One of the single washer spacer insted of the two.
The other is the crossmember installed.




Job done.
Top of pagePrevious messageNext messageBottom of page Link to this message

Robert Wort
Grand Master
Username: robert_wort

Post Number: 185
Registered: 12-2004
Posted on Tuesday, 12 April, 2005 - 11:15 pm:   Edit PostDelete PostView Post/Check IP

Read the excellent article by Richard Treacy and introduced by Bill Coburn on the above topics in the latest Praeclarvm today.

Excellent work gents. Let's not forget Pat's bit too which was also referred to in the same contribution.
Top of pagePrevious messageNext messageBottom of page Link to this message

John Beech
Prolific User
Username: jbeech

Post Number: 167
Registered: 10-2016
Posted on Sunday, 15 January, 2017 - 04:08 am:   Edit PostDelete PostView Post/Check IP

Folks, what is "Praeclarvm"?

Also, it would have been very nice to have a wide angle photo showing the area to be worked on.
Top of pagePrevious messageNext messageBottom of page Link to this message

Brian Vogel
Grand Master
Username: guyslp

Post Number: 2198
Registered: 6-2009
Posted on Sunday, 15 January, 2017 - 04:58 am:   Edit PostDelete PostView Post/Check IP

PR∆CLARVM is the RROC Australia's club magazine, with the subtitle, The National Journal of the Rolls-Royce Owners' Club of Australia.

Even though I seem to have 2 PDF copies of said publication I cannot seem to locate any online archive at the club site or on rrtechnical.info for it.

Brian
Top of pagePrevious messageNext messageBottom of page Link to this message

Brian Crump
Prolific User
Username: brian_crump

Post Number: 152
Registered: 2-2007
Posted on Sunday, 15 January, 2017 - 06:37 am:   Edit PostDelete PostView Post/Check IP

Brian - try this: http://praeclarum.rroc.org.au/
Regards,
Brian
Top of pagePrevious messageNext messageBottom of page Link to this message

Brian Vogel
Grand Master
Username: guyslp

Post Number: 2199
Registered: 6-2009
Posted on Sunday, 15 January, 2017 - 07:07 am:   Edit PostDelete PostView Post/Check IP

Thank you very much Mr. Crump!!

I don't know if this isn't better publicized on other parts of the RROC-Australia affiliated websites because it's supposed to be a members-only benefit or not. If not this should definitely be added so that it's prominently featured on both rrtechnical.info and on the main RROC-Australia web page.

Brian
Top of pagePrevious messageNext messageBottom of page Link to this message

Brian Vogel
Grand Master
Username: guyslp

Post Number: 2201
Registered: 6-2009
Posted on Sunday, 15 January, 2017 - 11:32 am:   Edit PostDelete PostView Post/Check IP

Also, the article regarding reinforcing the final drive crossmember is posted on rrtechnical.info:

http://rrtechnical.info/finaldrive/FinalDriveCrossmember.html

Add Your Message Here
Post:
Bold text Italics Underline Create a hyperlink Insert a clipart image

Username: Posting Information:
This is a public posting area. Enter your username and password if you have an account. Otherwise, enter your full name as your username and leave the password blank. Your e-mail address is optional.
Please quote Chassis Numbers for all vehicles mentioned.
Password:
E-mail:
Options: Enable HTML code in message
Automatically activate URLs in message
Action: