[jetbill]

*Edit: Changed the name of the thread, as I go through getting the new car dialed in for Sebring track duty (mostly PCA DE instructing with several students in the car) and the need for Autox FTD’s stickers) I’m logging some experiments as an early adopter of a new platform...(and in an attempt to not "ruin my car"...)

Stock vs KW HAS
Both spring front and rears of the stock and KW face-to-face dimensions at static ride heights are compressed to approx 4.00" and 8.00" (F/R), spring lengths are 8.5/11.0 (F/R) so you can look at values at the displacements at 4.50" and 3.00" respectively as starting rates with spring characteristics of linear front and progressive rear for both.

Note the tuning philosophy provided by KW, specifically in the front is a softer than stock (stock 260F/960R - kw 200F/900R+) spring coupled with a higher than stock rate bump stop, compared to stock which appears to be a higher rate spring with a slightly lower rate bump stop. This explains a bit of loss of steering "sharpness" experienced by what appears to be a 30% rate reduction from the stock rate. It also explains why the car bottoms out on speed bumps on my mid-pipe (with just a slight drop). Unless you are lowered so low, you are into the exponential function of the bump stop.

Might be good for some who like their cars really low(?), but not for me.

In summary - a total of 11mm front and rear drop is acceptable assuming maintaining the factory balance of front to rear bump stop engagement.

Interesting data points..
-TUV cert in kit denotes front as a progressive spring characteristic and rear as linear, data below shows the opposite.
-At rim centerline to fender measurement of 14.75", KW bumpstop starts its engagement.
-At a respectable Front ride height of 14.00" already 0.75" into the bumpstop.
-In the rear, 14.25" provides 14mm of clearance (shock body to bump).
-Minimum drop setting in the manual of 13.94" in the rear can not be obtained without extra parts. 30mm coil spring spacers in the rear were required, as the highest KW HAS setting was still too low and was engaging the bump stop 8mm at static ride height.
-40mm "A" dimension in KW manual provided a ride height of 13.25" (too low).
In summary for those that have this issue, for (whatever reason recommended by KW) to add this spacer at the owner's cost (not replace spring), I'd recommend a 15mm coil spacer that is manufactured by KW.
-1" drop provides a final Front camber rating of 2.2-2.4
-Bump stop lengths:
Front:
Stock- 75mm PUR model 22727110 DE (BMW model 3130 8091402-01)
KW- 64mm (consistent with KW TUV cert) PUR model 652 10 526

Rear:
Stock- 65mm PUR model 227271 10 DE (BMW model 3353 6859769-01)
KW- 54mm (consistent with KW TUV cert) PUR model 652 10 957