BMW M3 owners have reported 1 problem related to brake master cylinder (under the service brakes category). The most recently reported issues are listed below. Also please check out the statistics and reliability analysis of BMW M3 based on all problems reported for the M3.
In a situation where the car is stopped and light pressure is applied to the brake (hvac is off) the idle of the car will fall below specification and the idle becomes rough. Even a very slight decrease in brake pressure will return the idle to spec. This would seem to me to be a problem with either the vacuum booster or the master cylinder. I have noted many others with the same symptoms in online forums. At the very least it is an emissions issue and at worst a safety issue. I am prompted to log this complaint given today's news of 328i brake investigations. I have called Bmwna to get no satisfactory response.
See all problems of the 2008 BMW M3 .