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      01-03-2013, 10:51 PM   #30
BIU
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Drives: 2008 A22 E90 M3 DCT
Join Date: Apr 2009
Location: Hong Kong

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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.

That makes perfect sense and you sir are a scholar

My only concern was the V3 springs possibly unseating from the car going on a lift (No weight of car)

Last edited by BIU; 01-03-2013 at 11:24 PM.