105 rear suspension - solution to strange problem

["Leslie J. Singh" <Les.Singh@domain.elided>]

Hi All

The following message I sent yesterday is posted in full below in case it
could help someone with a similar problem. I got an excited phone call from
John Langley last night to say that he thought I was nuts when I made the
suggestion about the Trunnion, but in fact that's what it was - a twisted
trunnion.

Regards all.  Les in Wellington, New Zealand

John

Really sorry to hear about the problem with your gtv. What is more puzzling
is that you seem to have gone about it pretty thoroughly and chekced
everything. There is something definitely askew because the car should not
sit loweron one side, presuming that the springs are seated properly both
top and bottom and the trailing arms haven't been swapped around, not that
should make any difference - I'm running the right arm on both sides having
broken my left one which had urethane bushes.

Try triangulating from the trunnion to body mounting points to the diff
housing centre up at the top - that will tell you whether the trunnion is
out. Trunnion also needs to be checked for twisting in the horizontal
plane, any of these will cause the effect you've described. Measure
everything, sort of like you've been doing but also check the arms for
straightness with a straightedge. These are simple things and really
clutching at straws because without looking at the car I couldn't tell what
is wrong.

One other thing check the camber of the rear wheels - just use a level
vertically the bubble indicator is ok for this purpose - I set my front
camber by this method initially - don't tell anybody!

Raise the body and let the whole suspension droop with the shocks
disconnected - any obvious twists?

Got a good 4 wheel alignment operator down there? people have the equipment
but many of them don't know how to operate it.

My immediate thought is that if the springs are seated correctly then
something is wrong in thetrunnion department.

Sorry I'm not much help but please keep me informed and perhaps throwing
some ideas around we can solve the problem.

The discussion group is the Alfa Digest - I still subscribe.

Regards

Les
At 07:41 AM 10/20/99 +1200, you wrote:
>Dear Les
>alfa gtv 105 rear suspension problem
>
>Sometime ago you provided some good advice to me via a alfa e mail 
>list, the name of which escapes me  as i am no longer subscribing,
>anyway i wondered if you had any advice for my current problem
>
>I have gradually been doing up the front and rear suspension. This has
included
>1) bilstein shocks front and rear
>2) new springs front and rear (ex centre line -ak; slightly lower than
normal)
>3) new bushes on the trailing arms (front end and rear end of)
>4) and bushes on the reaction trunion (both the diff ones and those 
>at each end of the arm)
>
>Its 4) which appears (although i am not entirely sure; see below) to 
>have presented me with a problem which is as follows
>
>a) the whole back end is 10 mm too far to the right - but i cannot 
>move it any further to the left because the trunion arm is on the 
>left of the diff and diff is tight up against it ??
>
>(this 10 mm is very noticeable because it means the back end is 20 mm 
>too far to the right)
>
>At each end of the trunion arm (where it mounts to the subframe of 
>the car) there is a spacer. I tried leaving this out on the left side 
>(to pull the arm to the diff further to the left ) but all this 
>seemed to achieve was that stretching  of the bush but no real 
>movement of the arm which connects to the diff.
>
>b)as measured at the top outer edge of  the rear wheel arches the car 
>is 20 mm lower on the right side (due to 10mm bias to the right 
>slightly skewing the spring?) (front is ok)
>
>I have pulled the entire back end out and checked
>a)  springs werent broken, and are same length
>b) the placement of the new bushes on the outer ends of the the 
>trunion arm and the inners are flush with the stubs on the end of the 
>arm.
>c) shocks are ok
>
>Now when i say it appears that this is a new problem i should explain 
>a bit more:
>
>some time earlier I got the diff done up by a guy in chch and he took 
>it out for a road test and hammered into around a around -about at 
>which point the left wheel rubbed on the body (rear innner- near fuel 
>tank)
>
>This test drive was before i started replacing all the suspension 
>bits -so i assumed that it was simply a sloppy back end. well perhaps 
>that was part of the problem but perhaps also i had always had this 
>off set problem (on the other hand it would have been picked up in a 
>wheel alignement check surely-which i had a few months back)
>
>by the way i am running 185 70's and they are the same size and brand 
>on each side and equally inflated.
>
>I actually had red urethance bushes in the reaction frunion at the 
>diff and replace these with std rubber ones thinking they urethane 
>ones were too hard and precluding take up which would allow movement 
>to the left. anyway it didnt change things at all
>
>Oh there is no evidence of any rear structural damage to the car (i 
>have checked in the boot and inside under back seat)
>
>your suggestions as to what to check next would be appreciated
>
>
>
>
>
>
>
>
>
>
> 
>John Langley
>Injury Prevention Research Unit
>Department of Preventive and Social Medicine
>University of Otago Medical School
>P.O. Box 913,
>Dunedin, New Zealand
>Phone: 64-3-4798511
>Fax: 64-3-4798337
>http://www.otago.ac.nz/ipru
>

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End of alfa-digest V7 #1106
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