Supples’ Pub

So a recent discussion on the GTO forum prompted my attention. A guy had a similar suspension setup to mine, although with the Pedders coilovers up front. The coilovers allow a height adjustment of up to 1.25″ below stock - my front springs are a 3/8″ drop. Even with the coilovers cranked all the way down, he did not have the “rake” (rear end higher than front) he wanted with 1/2″ rear drop springs (like mine).

He started a thread on this and the head Pedders guy in the U.S., “JusticePete,” came in and started helping him diagnose. Among other things, the nugget below came out of that discussion. Apparently when using lowering springs front or rear, you need to “reset” the control arm bushings. The explanation is below.

The rubber bushes pressed into the control arms at the factory do not rotate in the control arms. The ferules inside these rubber bushes are bonded to the rubber. They do not rotate either. When the control arm bolt is tight to the ferule the rubber bushes become part of the suspension. They provide a certain amount of resistance on the bound, spring back to the neutral / timed position and then resistance on the rebound swing and spring back to the neutral position. If these rubber bushes are not timed to your new ride height the car is out of time — out of balance. While re-timing these bushes is standard practice in a Pedders shop it is almost an unknown every where else — except at the OE engineering facility where they use this in the design of your suspension. Failure to re-time the bushes results in premature wear, uneven ride height and uneven performance.

It is regular work when you do it on the alignment rail type lift. Actually doing this on your driveway is a really tough job. It has to be done with the weight of the car on the wheels with a 1/4 tank of fuel and the car empty of everything else on a level surface. That means you are crawling under the car to tighten control arm bolts and the car cannot be jacked up. If you can’t do this at home and really want to do most of your own work on your car let a Pedders shop finish the job up and do your front and rear cradle alignments at the same time.

This caught my attention not only because I lowered my car, but because my rear ride height is a wash. Just looking at it visually, some days it looks lower than the front and others it looks even. Before I get bent out of shape, I need to measure the ride height on a level surface with a 1/4 tank of gas. And if I’m going to bother popping the control arm loose, I oughta just replace the crap ass bushing in there. And well, you know how it goes from there…

Source: LS1GTO.com Forums - Pedders ride height/other issues?(long…)