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      02-24-2013, 12:42 PM   #32
ortho281
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Drives: 2011 E92 M3 6MT
Join Date: Aug 2010
Location: Katy, TX

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Quote:
Originally Posted by Richard@M-World View Post
V3 for E9X M3 do not come with helper springs. They will stay seated at full droop.

The springs used for V3 are soft enough such that they compress sufficiently (from full droop to normal ride height) by the weight of the car to deliver proper ride heights.

For Clubsport, higher rate springs are used. Therefore, the springs may not compress sufficiently by the weight of the car to reach a reasonable ride height. To address this, the front axle lower spring perches have to be moved down to "lower the car" if you will. But this creates a gap between the spring and the spring perches. That's why helpers are added.

Looking at it using math:
(The numbers are made up)
  • Spring rate: 500 lb/in
  • Corner sprung weight: 1000 lb
  • Spring will compress 1000/500 = 2 in
But, we need suspension to compress 3 in to reach normal ride height.

Solution: move spring perch down by 1 in.

New problem: there is a 1 in gap between spring and perches at full droop.

New solution: add helper spring.

This may be a bit confusing so let me know if this makes sense.
Hi Richard, Makes perfect sense! You answered many questions. Here is another. The KW S/O are progressive and also does not require a helper spring, even set to max lowering. Are the S/O spring rates similar to that of the V3?
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Last edited by ortho281; 02-25-2013 at 12:36 PM.