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      06-10-2013, 06:21 AM   #53
ajsalida
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Drives: 95 M3, 02 R1150GSA, 09 335xi
Join Date: Aug 2010
Location: SW USA

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Quote:
Originally Posted by thegrinchboy View Post
NICE!!!! Thanks for the update and good work! I was thinking about adding the M3 sway bar/bushing as part of the spring swap out to ZSP. Now, you went with the M3 rear sway, M3 bushings, the bushing inserts, and the Koni at 1/2 turn from full soft, interesting... Part of my upcoming spring swap out was going to include dialing back the rear Koni to 1 turn from full soft. If it still as compliant as you say, may be I will dial it back further. Love to hear an update after a couple days/weeks of driving.
Well on the dialing back to 1 full turn off soft. Couple of things. If that other thread you posted up about spring rates was right about rear Eibachs being linear and stock rate then adding a bigger bar, stiffer bushings and stiffer rebound onto stock rate is a lot. Full soft they are already stiffer than stock shocks. Something to consider.

Other thing is people tend to not understand all the functions of rebound on shocks. First since it is a damper it resists motion, with force proportional (roughly) to velocity of piston rod. But there are low piston speed and high speed effects. Keeping the tire on the ground over bumps is one, the other is governing rate of chassis dynamics and weight transfer (F/R side side and corner corner). The latter is more a low speed function.

Point is a softer setting lets weight transfer faster. A bigger rear bar already slows down the side-side roll, stiffening up the shocks will slow it down more. I was thinking after my test drive I might want to slow down the weight transfer in front, that is stiffen up the front a little.

Too much rebound will also slow down the high speed damping, and that is why for example when people complain about rear feeling loose over bumps I ask what their shocks are set to. To much rebound WRT wheel travel over bumps will not let the susp extend fast over small bumps so tire does not stay in optimal contact with the ground.

Trick is finding the softest settings that do everything well and playing the low speed chassis dynamics against high speed tire behavior over surface irregularities.

edit: and that is with only rebound adjustable. Compression damping and sway bars on many cars are also adjustable, some with separate high and low speed damping.
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