Originally Posted by italyix
Yeah ty, math was never my strong point. Im not saying to run 1200lb in the rear. If one plans to match the rear spring with the front, the equivalent oem location would require a 1200lb spring to match the front, hence why a rear coil over makes sense. Now, will the towers crack? Idk, but GTS runs a rear coil over.
I'm not the most knowledgeable person on suspension set ups but idk why anyone would want to match the front effect wheel rate with the rear on the e9x M3s? Especially with the weight of the engine slung over the front axel. Im guessing thats why M3SQRD used the OEM "wheel rate" ratio (1.70:1 front to rear) of approx ~460 lbf/in Front and ~270 lbf/in Rear. Hence brings you to around a 800lb rear spring for oem locations and ~ 300lb rear spring for a coilover rear location.
I would think having a 1:1 effective spring rates on the front and the back would be really stiff in the rear.