Quote:
Originally Posted by wesleyan92
I don't think it is the parking brake. The sound and thud and vibration are substantial enough to think it is something way bigger.
OP - my build date was March 2021.
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I agree with you. I don't think the parking brake is
the cause of the sound/shudder I hear, which is "something way bigger" and more powerful in nature. But, the parking brake could be the catalyst for the sound/shudder event. At least, I'm not ruling it out. I think
ashmostro has a point and here's why:
Both the rear differential and the parking brake are electronic-activated. The M Active Differential is in a league all its own, with many input variables contributing to "lock" based on software and its electronic-mechanically operated multi-disc clutch. Is it possible that a premature/maladjusted parking brake is holding off the rear differential via its lock control unit from "relaxing" at ignition cut-off? Is there tension in the differential that should have been electronically "released" once the car is stopped, just prior to ignition cut-off? [Admission: Though I've worked on domestic rear differentials, I have little knowledge of how the M5's differential really operates.]
I still think the rear differential is the source of the sound/shudder at cut-off, but am unsure of whether the parking brake may be the actual initiator somehow. The fact the event doesn't happen every time throws me a little, as does the fact that the sound/shudder occurs without touching the parking brake; but, the electro-mechanical nature of both systems and a possible relationship between the two is why I couldn't ignore the possibility. Just my $.02.