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      08-23-2019, 12:31 PM   #14
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Drives: 2011 135i, Space Grey
Join Date: Apr 2014
Location: Silicon Valley

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Originally Posted by bbnks2 View Post
Seems odd to be contacting the chassis unless TCkline packaged/matched the struts, bump stops, and spring rates poorly. I have about 2-2.25" of bump travel and don't have this issue lol. The fact that you are contacting the upper wheel well means you have too much bump travel.

Are the TC Kline struts adjustable (threaded body)? To solve the contact issue without sacrificing bump travel, I would raise rear ride height 3/8" with spring pre-load, turn the dampers up 1-click to compensate, and then make the strut body longer by 1/4" or so. If changing the strut length isn't an option then use the packers or look for a better/longer/stiffer bump stop.

Remember that the contact point between the wishbone and chassis is inboard from the strut. The wishbone will not travel in 1:1 fashion with strut travel. Motion ratio... If you have 1-2" travel at the strut then the wishbone may only move something like 3/4-1.5." Looks like TCKline is using very tall stock style "spring supporters." You may only have 1" of travel until you get into the bump stop but the bump stop probably compresses another 3/4-1" under load. The evidence of contact is clear but maybe something just got jammed up between there?

Can you jack the entire rear-end up, then use another jack to jack up one tire until you get into the bump stop (full compression)? Then take another pic? I can do the same tonight and see where I end up with the M3 subframe.
IIRC, Houtan is also running the rear M3 shocks using the M lower control arm, I wonder if those shocks are shorter for some reason.