Help with my brakes what do i do

[jasamja]

hey guys just got this M5 from a buddy of mine, it was invoked in a small accident (hit a sidewalk with the passenger wheel) damaged the wheel control arms and caliper, and the car has been sitting like that for 2+ years (actually caliper was removed at the time of accident)
i got the car from him and have now fixed it up with new control arms, wheel and a used caliper. so upon installing the caliper i have noticed the pedal went all the way to the floor and would only go back to normal if i pumped it 3 or 4 times, so we did a complete fluid flush as there was air in the system (car sat with no caliper for 2 years so that was understandable)
so did a quick bleed and nothing happened, so he ordered a a nice brake flush pump and today we did a full flush and bleed 3 times, and its still doing the same thing, however today i noticed that if you start the car the brakes pedal feels perfectly fine, its not until you put the car into gear and start moving that the pedal falls all the way down to the floor, and unlike before when you needed to pump the pedal 3 or 4 times now all you have to do is pump it once and the pedal feels normal, so that has improved however there is still an issues. he had the car scanned (he has a BMW computer) and no faults were displayed, does any one have any idea or advice to what the issue could be

FYI brand new Pads and Rotors were installed all around as well

Thanks

[SapphireM5]

Originally Posted by jasamja

hey guys just got this M5 from a buddy of mine, it was invoked in a small accident (hit a sidewalk with the passenger wheel) damaged the wheel control arms and caliper, and the car has been sitting like that for 2+ years (actually caliper was removed at the time of accident)
i got the car from him and have now fixed it up with new control arms, wheel and a used caliper. so upon installing the caliper i have noticed the pedal went all the way to the floor and would only go back to normal if i pumped it 3 or 4 times, so we did a complete fluid flush as there was air in the system (car sat with no caliper for 2 years so that was understandable)
so did a quick bleed and nothing happened, so he ordered a a nice brake flush pump and today we did a full flush and bleed 3 times, and its still doing the same thing, however today i noticed that if you start the car the brakes pedal feels perfectly fine, its not until you put the car into gear and start moving that the pedal falls all the way down to the floor, and unlike before when you needed to pump the pedal 3 or 4 times now all you have to do is pump it once and the pedal feels normal, so that has improved however there is still an issues. he had the car scanned (he has a BMW computer) and no faults were displayed, does any one have any idea or advice to what the issue could be

FYI brand new Pads and Rotors were installed all around as well

Thanks

You may have to activate the ABS module and do the BMW bleeding process. If the car sat like that for awhile it could have drained the other master cylinder for the front calipers and you may also need to bleed the other front caliper too. You have air trapped somewhere. Try bleeding the other front caliper too then try the BMW bleeding process.
GL

[jasamja]

Thanks again for the answer as well as on the suspension issue, i was able to source out a really cheap Used Master Cylinder and Brake booster, i was thinking of getting that installed but will try this method first