Does anyone know the spring rate for the stock WS6 rear springs, Code NYM (stiffest)? I have some eibach lowering springs I had planned to install, but they seem softer then the stock springs. The eibach's seem softer in my super scientific way of jumping on them. I don't have a good feeling about installing softer then stock springs on the rear. My fronts are the stock WS6, FJH (Stiffest). I used the lowering ball joints on the front.

From searching on the form I've found that the eibach's spring rate is 131-308

As far as I know, the spring rates varied depending on options.

That being said, I'm thinking its somewhere between 180lbs - 2xx ... Not sure but there are more factors involved in suspension stiffness than just the springs.

Are you going to match the rest of the suspension components together? There's a really good thread on this topic in the archives somewhere - but I don't feel like jumping through the hoops of the search function from my phone.

The spring rates for the Eibach Springs in a Pontiac Fiero application is 350# per inch per Eibach tech support.
It is the same rate front and back with a 0.8" decreased height.

I do not know the exact spring rate for the WS6 springs or if they vary year to year.

Here is a list of the spring part numbers and RPO codes:
http://floridafieros.org/osg/springs.html
Not sure how to find out the actual rates for them.

Doug Chase had some springs measured and his results are here:
https://www.fiero.nl/forum/A...020825-2-020192.html

Can't give you exact numbers, but from personal experience (upgrading my own car), the Eibachs are much stiffer than the stock springs.

We did a thread on this a couple of months ago. We did conclude that the Eibachs are progressive rate. If you have something specific you want, try Eaton Detroit Spring.