I think that I have got a braking problem with my 750i.

Wen the power is turned off, I can push the brake pedal many many times. It never gets hard.

Although this is my first car with the brakebooster system.
My other cars had a very firm/hard brake pedal after step 3 or 4 times on it when the power was off.

Can anybody tell me if this is normal or if it is a problem.
And how can I fix that?

I already replaced the brakemastercilinder.

Thanx for any help!