Aluminum trailing arm installation in early car

kent olsen · kent olsen's Garage

Well I finally finished the installation of a aluminum trailing arm on the left side. I'm rebuilding a 3.0L so I thought I'd wait to replace the right side when I pull the engine. The hinge bolt is in backwards so you either cut it with a hacksaw or pull the engine.

Now the interesting part. I went to the local Les Schwab tire dealer for the rear alignment. What I found was the left side (aluminum) would go out to 1.6 degs neg camber but only 0.65 deg positive toe (toe in). The original steel trailing arm on the right would only get 0.6 degs neg camber and 0.42 degs NEG toe!!! The rear is then steering to the right!!!

First of all I need to get the toe on both back to zero. Is there a way to shim the trailing arms at the hinge point on the chassis to assist in the toe adjustment.

Second why am I able to get 1.6 degs camber on the aluminum side and only 0.6 degs neg on the original steel, right, side? The 1.6 degs neg is what I really want. Is there a way to add a shim somewhere to help in this adjustment?

Steve@Rennsport · 07:06 PM

Kent,

Sorry I missed your call today,..I've been swamped.

Assuming that their alignment equipment has been recently calibrated and the alloy trailing arms are not bent, its possible the torsion bar tube may be bent a bit. If its necessary to fix this, the proper way to fix this would be to put the car on a Celette Bench (special frame jig) and straighten it out.

Sometimes, one can modify the trailing arm slots and spring plates to get more range of adjustment but I'd recommend having the rear suspension toe chnage curves checked to ensure that they are equal, side-to-side after that.

AFAIK, there are no shims to correct this situation. I've never seen anything made for 911's in that regard.

Whenever used alloy trailing arms are to be installed on a car, they should be put into a jig to check them for straightness before installation.

kent olsen · kent olsen's Garage

Steve

Well the funny thing is I was able to get at least 1 deg neg camber with the original steel arms. Now how does the aluminum side get to 1.6 degs neg? I've heard that's about all you can expect unless you go to that adjustable spring plate.

I guess I'll drive it for now. I've got the 3.0L long block in my shop and that's what I'll be concentrating on this summer. Once I get to the assembly point and I have to pull the 2.7L out of the car for all the parts that will be used on the 3.0L I'll hang the other trailing arm and see what I get.

Mr9146 · 06:15 PM

With all due respect to Steve, THE TUBE IS NOT BENT!!!!

I am dealing with this EXACT SAME issue right now. I have adjustable spring plates (SC and Sway A Way) and the problem remains.

I would like to talk with you about your situation ... please PM me.

BTW, what year is the car in question?