madmaverick wrote:
Yoshi wrote:
the cosmo coilover kit is 450lbs front and 650 rear I think. the Ground Control kit is 550 front and 750 rear.
i think thats 9kg fromt and 11kg rear if youre going with kilograms and 10kg 12kg for ground control.
Wow, those ground control springs are pretty stiff. I have 12/10 spring rates on my S13 and its WAY oversprung, to the point that I lift tire mid-drift on flat pavement:

Im pretty sure the e30 is a lighter chassis when properly prepped and about the same weight stock, it would seem that the cosmo kit is a better rate to go with.
I know this is old, but I figured I'd answer this since I was discussing that with my friend when I was going with cheap coilovers a while back...
It's all the geometry and leverage needed to compress it. The E30 just has the spring located in a weird spot which bears a lot of weight and needs to be higher rates for the same amount of support as a lesser weight spring if it were right on the shock. Like if you ran a 800lb spring in the normal location, you would use like a 500lb spring if you were to have it on the shock.
Also, I posted this in another unlreated thread but it applies more here

I uploaded pics of the Cosmo Coilovers that I installed a while back here:
http://www.flickr.com/photos/dotcommie/ ... 242555007/