suspension setup advice? handles great but rear end is a brick

tabstang said:

Of most interest to me are the low rates on the Boss 302 ... 148F/186R lbs/in,
Boss 302 Laguna Seca 137F/191R lbs/in. These seem REALLY low for a performance oriented car - and higher in rear than front - ???. Am I missing something here?

Click to expand...

Tab,

I'm not sure about the Boss but I know on my 2011 GT the front bar is actually glued (wtf!!) to the sway bar bushings. So the effective front wheel rate likely is higher than the reported spring rate at ride height. Something about reducing squeaks. I don't think it was glued on the 2005-09 models. The rear asb is not glued.

Also remember the Boss models came with a staggered setup so more rear bias may be appropriate?

It seems a lot of the custom coilover track setups run approximately twice the spring rate in front as in back, just as a general reference point. But as you say, lots of variation depending on sway bar sizes, rear spring mount location, etc.

Just went through this with a customer who had one of our lowering spring + Bilstein kits.



As Norm pointed out, if you haven't chopped the rear axle mounted bump stop down, that is going to cause major problems.



Cut the top portion off above the lowest "ripple" in the molded foam bump stop. Do that first before chasing any other options. This is almost always the problem.



The stock ride heights on an S197 are hilariously tall - and lowering them 1-2" is common. But so is running into the rear bumpstop, after lowering...

Cheers,

That was the solution! I had already cut the axle-mount stops so I thought they were OK - but I left too much on there. Ground Control advised me to cut both the axle mount and body mount stops in a tent shape, and that did the trick. It's a firm ride (as expected for sport springs) but no more spine-banging on the big bumps. Thanks everyone for all your advice. In retrospect I should have gone straight to this solution but instead I had to permutate every possibility before acting - not the first time I've done that! While I was in there I finally got my panhard properly adjusted - bonus!