I've been dealing with this for a while but I just never thought to ask. When I come across several bumps in the road, my acceleration somewhat gets thrown out of whack and the rear end seems to bounce over the place. Is this due to fact that our cars don't have IRS? Is there a way to decrease this feeling? My suspension mods are as follows... FFRP K Springs, FRPP shocks/struts, 295/35/20 rear tire. Thanks

 

To some extent, that's a solid rear axle trait, but my S197 has UPR Products control arms & panhard bar and it is A LOT more stable than it was from the factory.

 

control arms (LCA & UCA) will make this feeling almost go away.

 

LCA and UCA will not make these traits go away, at all. We have a solid rear axle, a watts link would help a little but the symptoms will still exist.

 

IRS is only going to help in a bumpy corner. On the street, which is the only place I drive, I have never felt the need for IRS and I do push it in the corners.

We need a better description of what's going on. You could be describing wheel hop. You should have lower control arm relocation brackets with those springs. Your staggered tires could be contributing to the problem, they aren't great for handling.

 

I only drive on the street also. Let me see if I can be more specific. When i'm accelerating (not hard, just gradually) on a straight bumpy road (even while making a turn), the back of the car just doesn't feel "planted." I guess it can be wheel hop, but i was under the impression that wheel hop only occurs under "hard" acceleration. Basically, what I'm saying, what kind of upgrades should I look into to "feel" more planted to the ground, even while driving on bumpy roads. On smooth roads, the car feels fine. Southern California is notorious for bumpy roads though, lol
Thanks guys for the input.

 

How much of a drop are K springs? If it's more than 1 1/2" you must have brackets.

 

K springs are 1.5 inch, but anything over 1 inch it's recommended. I'd do relo brackets even with a 1 inch drop, but get the ones with multiple holes for adjustment.

I'd get some relocation brackets and change the rear shocks to koni str T or some other shock made for lowering springs.

 

Sounds like the "hopping" on bumpy curves you are talking about are the symptoms that a watts link cures. A WL simulates (to the best that it can) an IRS. I just put a whiteline WL on mine and bumpy corners are no longer a problem. Single wheel bumps upsetting the car is history now. Corners can be taken crazy fast and you (mostly) don't lose the connected to the road feel. Like anything you can overdo it, and the rear will still come around but generally it really seems to let the suspension work unimpeded.

 

oops - double post