Someone please help me understand why all of the major coilovers for our cars do not allow ride height adjustment without affecting rebound/spring rate.

Am i missing something? Coming from the Supra world where all of the good coilovers have this feature. My 996TT has Bilstein pss9s, it drives me nuts that I couldn't adjust separately. I am looking to purchase a set for my 997TT and was hoping for a set with this feature that also supports PASM. I know, I'm asking a lot.

Educate me please. I'm sure there is a good reason.

 

Hi there, Bilstein Damptronic is the only coilover that supports PASM, so I assume you are asking about it. I discussed your question and related issues here, in post #187: https://www.6speedonline.com/forums/...-turbo-13.html .

In short, first it's important to follow Bilstein's official recommendation for ride heights reduction: 10mm-30 mm in the front, and 5mm-25mm in the rear. If you stay within these specs, then both dampening rates and spring rates should not change with ride height, at least not in a properly installed Bilstein system. In other words, ride height doesn't change spring/damper/ride/compliance characteristic. Any change in handling would be from the advantage of lowered center of gravity, and not change in the coilover system per se.

The risk of not lowering enough is coil binding, and the risk of lowering too much (beyond 30mm) is hitting internal bump stops. Either would be a dangerous situation (very little or no compliance at all) in either situation.
BTW, I do not recommend lowering any more than 25mm for other reasons: the 3D geometry of the suspension system is altered to much, leading to other problems and complications.