Last year I purchased a used Ground Control setup with KYB AGX shocks from a gentleman getting out of racing. The setup only had about 3-4 events on it and I got it got it for a steal. So now I’m overhauling my suspension and I have a few questions…

PROJECT OVERVIEW:
Subject car: 1989 GTUs NA. Currently with 100% stock suspension.
Purpose: The is my summer fun car. My wife and I take it on long trips and I drive it to work most of the summer. Autocross? Maybe in the future, mostly just spirited driving. IE: Ride quality is more important than max handling.

Right now the suspension is in pieces. All the rubber bushings are being replaced with polyurethane. I have a new set of Racing Beat sway bars for the front and rear and Toe eliminator bushings are being installed in the rear hubs.

QUESTION #1
So now I have to decide what shocks and springs to use. I know I’ll be using the KYB AGX shocks that I have. Should I use the Ground Control coil-over setup or purchase a set of RB springs? Which setup is going to give me a better compromise of ride comfort AND handling?

QUESTION #2
How do you read the Eibach Springs? IE: How do I know what the spring rate is from the model number?

The front springs have this written on them:
Eibach 71957 0700.250.0450

The rear springs have this:
Eibach 49895 0800.250.0325

I figured out the 0700 and 0800 is the spring height…7” and 8”. I don’t know what the “250” means. Does the 0450 and 0325 mean they are 450lb and 325lb rates?

Thanks for any opinions you have.
Jeff

 

You are correct. 0800 and 0700 is spring height. The 250 is coil diameter (2.5") which is standard for most coil over set ups. The last set of numbers is spring rate in in pounds, 450 and 325. These rates although much stiffer then stock really arent horribly stiff. It will be a much harsher ride, but there not so stiff to be considered "race" springs. I'd personally stick with these and keep the dampers onn a soft setting and see if its bearable for you, then decide if you want to go with something softer. Replacement 2.5" coils arent too expensive, so you can retain your coilover set-up and still have the ride height adjustability if you do decided on a softer set of springs instead of buying a street/stock replacement "lowering spring". or you could just sell me your whole set up : :

~Mike...........

 

I figured the spring rates were the last number... just wasn't sure. Do you know of anyplace that lists the spring rates and sizes? Where would I go for alternate springs?

I read the GC info at: http://www.brfoundation.com/RX-7/gcinfo.htm
I gathered from his experiance that 450lb and 325 lb springs were going to be overkill for a street machine.

I maybe selling the coil-over setup in favor of RB or ST springs. I need some more opinions right now about street performance with this setup...

 

ive got agx and gc coil overs 450 front 300 back.... wouldnt change them for the world.. to me its just right.. i have my setup 4 in the front. 6 in the back

 

also that guy didnt have adjustable struts..... being able to adjust them makes a huge difference... and the non adjustables probably couldnt handle a harder spring as well as oursput them on.. being that they are coil overs you dont need a spring compressor to take them off

 

Good point. I just noticed that. Sounds like you think I should try the coil overs at 450lb front and 325 rear and see how I like it?