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Old 10-28-2025, 08:32 PM
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andrewwynn andrewwynn is offline
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Quote:
Originally Posted by e70jane View Post
Andrew, when you ask me to loosen the mc from the booster to see if the brakes will release, do you mean that once the car starts acting up again, and I am pulled over onto the shoulder, keep the car on and pop open the hood to loosen the bolts?
You can wait until it acts up or you can do it first to see if you can get it to act up.

The theory is when hot the push rod in the MC is expanding and engaging the booster. The tolerance is very tight like 24/1000 and if they start out touching you will get the exact behavior you are experiencing.

If that fixes the problem the "proper fix" would be to remove the MC, measure the depth into the booster and the length of the rod coming out of the MC and file down the rod until it's the proper length.

Most cars have a threaded rod coming from the booster and and you use a special calibration tool to measure and set it. BMW doesn't they are made one size at the factory.

If this happened to my car i would loosen the nuts to get the rod gap to work by trial and error and then I'd shim the MC away from the booster using shims in numerous places around the base of the MC.


–awr–

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