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      09-05-2019, 04:03 PM   #51
Racer20
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Drives: F80 M3, 228i THP, E46 ZHP
Join Date: May 2009
Location: Ann Arbor, MI

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Quote:
Originally Posted by Encanto View Post
The LCI OEM documentation stated the 5-bolt change as part of the chassis changes to improve steering feel and suspension tuning. These changes started with late MY2015 F3x and F8x production.

Both steering gears show the clunk, some without suspension mods, most with the mods. You have quite eliminated all possible causes of this clink -except the steering rack. And that's the part that BMW replaces when everything else fails to eliminate this noise - but only when the suspension is OEM. My brother's 17 M3 has this clunk with Eibach V2, my 18 M3 with Eibach V1 does not. We are going to try the steering rack adjustment once we get the tool.

Most probably you have been the only person outside BMW that have gone this far in finding the root cause of this problem, and for that thank you very much.

Quote:
Originally Posted by Racer20 View Post
The only reason the 5 bolt mount would increase steering feel is if there was too much compliance in the joint. Which is exactly the same thing that would cause this clunk noise.

The F3X and F8X gears are completely different, made by different suppliers. I haven't seen any actual evidence that the noise is coming from the steering gear on the F8X, and plenty of evidence indicates that this is the problem (on my car at least).
Being in this field, I'm familiar with the difference between what marketing materials claim vs why something was actually done. Both are true . . . Steering response is probably better, but that would only occur if the joint was insufficient rigid in the first place.

I'm not fully buying into the steering gear explanation yet because it doesn't fit with the evidence (on my car) but I'll certainly be happy to be wrong. At least that means it's fixable.

Keep us posted, looking forward to hearing if it solves the issue for you.

Note that my clunk is significantly louder and heavier than the clunk I heard on the 2017 car I drove. There very well could be multiple things going on here.
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2015 M3, 2005 330i ZHP, 2015 228i 6MT Track Handling Pack, 2007 M Coupe (Sold)