If the brake booster pin is misaligned it will apply the brakes usually somewhat slowly but eventually full application.

All the BMWs I've helped with have no adjustment so usually the fix is to shorten the pin or shim out the master cylinder.

You can confirm by cracking a brake pipe at the MC to release the pressure.

I forget the correct name of the pin from the booster to the MC but that very much matches your symptom and also almost always happens shortly after the MC was replaced.

This was a recent thread on XO and the fix was thin washers between the booster and MC.


–awr–

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)