E36 Spring rates/Rear Coilover....

[trakday]

Good day to all and hope we are all in good health.

Planning on ordering MCS 2ways w/ External reservoirs for my 1995 E36 M3. Car is fully caged and gutted by FALL-LINE...its classed for GTS2. Rear Strut tower's are reinforced with the cage tied into it. Will be running on 17x8 wheels and 245/40 slicks. Brakes are Brembo BBK on all 4 corners.

Now the question is what is the ideal spring rate for a set up that has a full rear coilover? Car has PTG rear wing and will be running the Bimmerworld Max Velocity version 2 splitter...or maybe something home made.

Thank you

[aeronaut]

If you order MCS from a knowledgeable distributor, they'll help you with spring rates even with the true coil over setup.
And/or call MCS directly. They're awesome.

But if it helps, it's my understanding that the motion ratios for the stock attachment points are:
Front: 0.94 damper and spring
Rear: 1.05 damper, 0.64 spring
So, assuming your true coil over setup uses the same mounting points as the oem damper, that gives a motion ratio of 1.05 for rear spring.
Wheel rate = spring rate * (motion ratio)^2