Viper Suspension Tuning

[Godsize]

I am posting this for my best friend who's been trying to get accepted into this board for the past month and a half. Sorry man, and you are the one with the Viper..go figure! Anyway, he has a 98 GTS with the Penske coilover suspension and Eibach springs. This past Saturday we decided to lower the car more than what the previous owner had in an effort to achieve a certain look. He had lowered the vehicle about an inch and had it aligned as you should. We lowered his GTS another 1/2 an inch. The car looks great but now my friend says the rear end feels very loose and comes around much easier than before. Now I know the car needs to be realigned obviously but I find it hard to belive that such a minimal adjustment in ride height would have such a drastic effect on the handling. Any comments or suggestions or similar experiences?

 

[Dave's Big Brakes]

Any change at all, makes toe and camber different.

 

[Frank Parise]

Dave is right on. Lowering the car without realigning it will result in higher negative camber and less toe-in (more toe out). You may have ended up with toe-out in the rear which makes the car feel unstable.

You imply that the car has been lowered by 1 and 1/2 inches from original factory settings. That is way too much for the suspension geometry to work in your favor. You should go back up at least 1/2 inch.

For good road course handling, at the axle centerline, the distance from the ground to the bottom of the frame should be about 4-1/4". Look for about 4-5/8" to 4-3/4" in the rear, using scales and your corner weights to dial the exact ride height in.

 

[Chuck 98 RT/10]

I find it hard to belive that such a minimal adjustment in ride height would have such a drastic effect on the handling.

A 1/2 inch is a mile. Big changes.

 

[GTS Dean]

Way too much lowering. Roll centers get bad quickly when you go too far. Toe out at the rear is to be avoided at all cost. Frank's ride height recommendations are very good, but a street car that low will scrape frequently and you'll begin losing side sill screws.