View Full Version : GC rear spring question for the BMW guys - Who went 4" in the rear?

04-14-2010, 11:13 PM
So, I have the GC 450/600 kit with 6" 450lb springs up front and 5" 600lb springs in the rear.
I have Koni G60 rado front struts and standard e30 m3 rear konis

I am looking for another 1/2" of drop in the rear so who has gone to 4" rear springs? And for those of you that did, what spring rate did you run?

I was looking at HyperCoil

http://www.hypercoils.com/Catalog.aspx - Click on 2.25id for the rears and you can get whatever you want for a reasonable price from a good company.

So who runs 4" rear springs what spring rate do you run?


04-16-2010, 12:40 PM
no one?

04-16-2010, 01:23 PM
I looked at 4" springs but after seeing how little travel they afford I decided to raise the rear spring mount into the body an inch and a half. It's more work but much better than hitting coil bind on large bumps. and the 5" spring affords more droop as well as the added compression travel. as long as the cup you're building into the suspension is less than 50% of the bound height of the spring you won't run into interference issues.( or at least you bind the coils before then) If you don't want you modify your car you could drop the lower spring mount into the control arm as well. (that way if you wanted to return to stock you still could by swapping in a set of stock control arms. ;) )

I have used Hypercoils on several cars and they have a good product though.

E30 (on the left would be easily modified as they are steel and plenty large for a recessed 2.5" spring seat)

E36 (demonstrates a spring seat dropped into a hollow style control arm)


04-16-2010, 09:50 PM
^ Hmm bro, I dont think I want to go around modifying the RCAs.

Anyone else run a 4" rear spring

04-18-2010, 04:56 AM
I know this doesn't answer your question, but I too am kind of in the same boat with my PSS9's. They don't go low in the rear at all even with just the spring without perches. The guy from TCKline said their "shorty" springs could be an option. http://www.tcklineracing.com/springs.htm Not too sure about the sizing though.

04-18-2010, 10:42 AM
I ran 4" springs on all four corners on my 6. No issues.