I have some ReSpeed adjustable rear springs, and my setup bottoms out on moderate bumps. My jounce bumpers are the original ones, with about half their height removed. When the car bottoms out, there's a fairly hard "thud", and I think this will upset the car when it's on the track. I want to try some of the foam progressive jounce bumpers, but I haven't found any that bolt into position, like the OEM ones. The other option is to put them on my shocks, but I don't know if the shock brackets are strong enough to withstand the forces generated.

Also, my rear spring rate is 175#. I'll consider upping the rate, but I want to try the progressive jounce bumpers first, since I'm happy with the handling balance the way it is.

Suggestions? Ideas?

 

what kind of bumps are you hitting? how low is your car? i have stock rear bump stops non cut and havent bottom'd out. (im using 175# eibach with 2 coils cut.) on the track/autoX ive never had any problems cuz those pavements pretty smooth.

 

The bumps are moderate ones, like the transition from a freshly paved section of road to an older one. As for the height of my car, it's fairly low. The only way to give a meaningful measurement is to go from the axle to the top of the bump stop (as installed), which I can't do this instant. But remember that my setup is different:
1. It's probably much lower than yours, since it was designed as a pure race setup.
2. Your spring rate is now higher than 175#, since you cut some coils.
3. Your spring may be progressive (are the coils closer together at one end?)

It's not a question of whether I need it -- I'm already pretty sure it's the best way to do it. The question is how to get some progressive jounce bumpers in there.

 

have a pic of the car? that may help.

i have eibach coil springs, not the progressives. the red ones. lol. but yea i have 330# up front and the 175 rear. the coils cut were dead coils.

 

the eibach springs have some dead coils, so you can cut em to set ride height and it doesnt affect the rate.

mine are uncut, its probably lower than stock but not much

 

I'm running the adjusters, with 150 Lb springs and Bilstein shocks. Can't say that I've ever bottomed out, no matter how hard the bump was. I can't imagine why you'd be bottoming out with the stronger springs. The rear of my car is very low due to the short lenght of the Bilstein shocks.