I know there is a sticky on spring rates. This is an attempt to revisit this and somehow get the JCW rates. I just measured them while I had the springs off the car using a VERY VERY primitive method. I set the springs level on a scale, zero'd the scale built a stacker for them and measure how much weight till the spring dropped 1/4 inch. Front springs dropped 1/4 inch with 40lbs stacked on them. Rear springs dropped 1/4 inch with 47lbs stacked on them. This was a far cry from an exact science. Mathwise that would make the front ~160 lbs springs and the rears ~ 188lbs springs. However my gut feeling says that's a wee bit soft.
Anyone got some real information?

 

No body? Really?

 

It is my understanding that JCW springs are variable rate; so you would need to test them over their range of motion.

 

That's part of why I figured my test was off. 160 / 188 just sounded way to low. I'd like to run about double that.

 

Any spring using the stock bumpstops will act as a progressive rate spring since the stock bumpstops are always in contact with the shock...

The rear spring isn't progressive. I don't know if the front is progressive since the barrel design confuses the look; this design shape allow the coils to fold a bit into one another yielding a little more spring travel.

My butt dyno tells me these springs are a little stiffer than stock and the valving a little tighter.