Alfa Romeo Forums banner

1 - 10 of 10 Posts

·
Registered
Joined
·
57 Posts
Discussion Starter #1
A little niggler that I can't figure out.

My mechanic has been waiting for the shims used to take up the space at the mounting points of the sway bar, torsion bar, whatever you want to call the bar across the rear end that is intended to tighten up the suspension. They've never been in the car since I've owned it and there has always been a sharp thunk or rap from the back end when I go over an uneven piece of pavement that works the left and right wheels independently. The mechanic originally said the shims would solve that. Now he says they're just plastic (?) and won't make any difference. It must be something else.

Looking at it from under the hoist and there is nothing that seems amiss... other than those shims.

Can someone tell me if the shims are likely the problem or if I should look elsewhere? I'm still waiting to receive them from Italy... :(
 

·
Administrator
Joined
·
16,629 Posts
Our '84 used to make a klonk from the rear when we went over a big enough bump.

I got underneath and saw that the sway bar (aka anti-roll bar) was bumping against the body on one side. I loosened the sway bar mounting bolts and used a pry bar to push the sway bar to the other side about 1/2". Then I tightened the mounts. No more klonk!
 

·
Registered
Joined
·
57 Posts
Discussion Starter #3
Our '84 used to make a klonk from the rear when we went over a big enough bump.

I got underneath and saw that the sway bar (aka anti-roll bar) was bumping against the body on one side. I loosened the sway bar mounting bolts and used a pry bar to push the sway bar to the other side about 1/2". Then I tightened the mounts. No more klonk!
Thanks Eric, I'll look to see if I can find a point of contact. We were not able to replicate the noise when up on the hoist.
 

·
Registered
Joined
·
293 Posts
Could be missing the rubber shims on the trunion (t shaped piece from the rearend to the body). Where it attaches to the body there should be a spacer about 1/4 inch on either side. If it is not there you'll get quite a thunk when cornering.

HOP
 

·
Administrator
Joined
·
16,629 Posts
Thanks Eric, I'll look to see if I can find a point of contact. We were not able to replicate the noise when up on the hoist.
To find the source of the noise in our Spider I had to get my son (~200 lbs) to jounce the back of the car while I was underneath (car up on jack stands). Having my wife (can't say her weight in a public forum but way less than 200 lbs) bounce the car wouldn't move the suspension enough to produce the noise & allow me to locate the problem.
 

·
Registered
Joined
·
150 Posts
I have a short steep driveway at my house and in order to get up it I have to be in 1st gear.

When I drive up the incline I notice a thud one or two times... sort of a quick sucession of thuds, like thud-thud-thud quickly a could of times. I suspect on the incline the rear axle is bottoming out, but haven't really investigated further. This thread had piqued my interest. Is the sway bar a common cause of issues for out of the ordinary noises from the backside of spiders? [opening for clever backside-related jokes :)]
 

·
Registered
Joined
·
243 Posts
thunk from rear suspension

hard to say from here really, but when get a knocking like that - one side at a time when going over bumps - a likely suspect is the rear sway bar mounting bushings. when they get worn out, they allow the bar to move up and rap the floor of the car. they can look OK when not stressed - but still allow too much movement. cheap and easy to fix.
another place to check is the "grommets" at the trunnion/diff joint.
the trunnion spacer/thrust washers are usually gone on most cars. they do not let things clunk - rather they let the rear of the car shift over the rear suspension/wheels - which makes for some very scary self steering from the back end.
good luck with it.
andy
 

·
Registered
Joined
·
57 Posts
Discussion Starter #8
Thanks for the comments. I'm still waiting for the 'shims' for the sway bar to arrive on the slow boat from Italy. I'll have a very close look at these other ideas at the same time as the shims get installed.
 

·
Registered
Joined
·
57 Posts
Discussion Starter #9
I'm still waiting for the plastic shims, however I'm almost convinced they won't solve the problem.

If I put my weight behind me and really work the rear suspension *sideways*... i.e., shake the car side to side, I can hear a clinking that I believe is part of the clunk/thump I hear when driving. My ace in the hole retired Italian mechanic is convinced I need shims for the de Dion arms (?) and explained how to line the car up (with string around all four tires!) to make sure it didn't dog leg or tend to steer from the back. This was without the benefit of a hoist mind you, but he's pretty smart about these things. Unfortunately he doesn't work on cars anymore!

So the question now is... will I have to have the shims machined or are they available? Does anyone have a diagram of how this all fits together?

Thanks,

Brock
 

·
Registered
Joined
·
293 Posts
Poly urathane shims, perhaps bushings is a better term, are vailable from performatek. Just cut the bushing ring through on one side, grease it up, and slide it in place.

HOP
 
1 - 10 of 10 Posts
Top