Originally Posted by elp_jc
Why do you expect them to cover a mistake made by the exhaust installation shop (or whoever installed it)? The most likely root cause of the failure was improper retorquing of those bolts. Most shops just remove those brackets, rather than fiddle with the rubber mounts, which are difficult to dislodge up there.
Another failure cause (not applicable to you) is to use the subframe as a lever to remove springs, rather than using proper spring compressors. Good luck man.
There are no spring compressors or leveraging required to do the rear springs. You undo 2 bolts and the spring pops out. Both bolts are irrelevant to the subframe and differential.
I was actually on the phone for about 1.5 hours yesterday trying to come up with a solution with BMW and BMW NA regarding this. This is beginning to get out of hand and kills any confidence people may feel in driving their cars.
Singletrack, yes I do have some updates. I have already designed the reinforcements and will begin to test them sooner than later.
I am also working on fastening solution that will improve on the mounting of the differential so it minimizes differential movement and compliance which causes damaging of the bolts.
I have also realized that stiffening the axle carrier (subframe) bushings such as the GTS, etc will reduce the chance of compliance in the system and keep the subframe from moving around and causing wheel hop which is the primary cause of this.