(crossposting from FRAXX) After really tossing my car around at El Toro this weekend, I feel that my rear is too lightly sprung (something that people here have brought up, since I've mentioned that I lowered the panhard).
I'm going to try a 300 lb spring (up from 230); however, I'd like the damper to be perfectly matched to this rate. I have Koni Yellow SA right now, would it be worth it to have my old Bilstein HDs revalved to match the spring? I'm looking at the Bilstein rebuild form, and I'm not really sure what to ask. "Hey match it to a 300 lb spring"? I'm trying to decide if I should just keep the Konis on as is.

 

What are your front springs? 300# is pretty serious spring. i have 250's but i haven't installed them yet.

Plan A-I would call Koni and ask how the Yellow SA's would work with 300# springs.
Plan B-Have the bilsteins revalved for the 300# springs

 

300 is kinda stiff. That's stiffer than what most people run. instead if getting stiffer springs you could get linear rate springs. Also and adjustable rear sway bar would help you tune. When you lowered you panhard rod did you only lower the chassis side? Lowing the axle side also help.

 

The new Ridetech HQ series monotube shock has enough rebound adjustment to handle your #300 pound spring. The adjuster is readily accessable making changes easy. Mounting is just like OE.

 

Do you have a pic of the PHB? How much did you lower it? Do you know your Roll Couple - front roll center and rear roll center? Do you have drop spindles up front so that you needed to compensate the rear RC that much? What front spring rate are you using, cast iron block? Stock rear or aftermarket rear? What wheels are you using? Plan on using a stock torque arm with 300# springs and lowered PHB? Track only car?
230# is plenty strong. I suspect you'd be better off bringing the PHB up a little without knowing anything other than that your rear is loose. And the experiment is FREE!

 

I have stock MOOG IROC springs cut 1/2 coil with Unbalanced Engineering's PHB relocation brackets (body and axle side) and lowered to the lowest (and only) hole and my rear rolls alot.

 

They looked good in the car Sunday; thanks for the instruction and setup input as always, it's on point.