Alright fellas... here we go.

Called Ground Control and spoke with Mark who said that they recommend a 400lbs setup on the rear for FDs... He was stumped as to why I had 350lbs on rear and worked fine on the previous FD but bottoming out on this one - based on the fact that I got the setup in late 90's from Nick at Ntech he said it is quite possible that back then people just didn't know what was the right setup for the 3rd gen Rx7.

Ok, so I ordered 0700.250.0400 springs, got them Monday.. put them in after work.. tested... EURIKA! Then for the rest of the week I tested it on all the familiar road where I normally bottom out and so far so good.

No more bottoming out, holds very well on even the roughest potholes. So I'm pleased to report this issue has been resolved.

Lesson learned - make sure you have the right spring ratio in your FDs boys! 500lbs in the front, 400lbs in the back, and increase if you're loading up your chassis with heavy objects (i.e. subwoofer boxes, amps, credenzas, office desk, etc..).

Here is my final Ground Control CO setup that works with a normally loaded chassis with a large 5 channel sony amp and subwoofer box with 2 10" subs:

Fronts: Eibach No. 0600.250.0500: 6" tall, 2.5" diameter, 500lbs spring rate
Rears: Eibach No. 0700.250.0400 : 7" tall, 2.5" diameter, 350lbs spring rate

Back on the happy road...

 

Glad you got it worked out.

FWIW...

I run 350# rear springs. No issues w/ bottoming on my car. I also don't have any stereo stuff though. Static ride height set at 25.5".

I used to run 7" springs. Now running 8" on the rear.