From ECSTunning:
$274.49
OEM (TRW) BMW Power Brake Booster - 34336760461
Has your brake pedal become stiff and hard to depress, or goes right to the floor with no pressure or feel, most likely the brake booster unit has failed.
Power Brake Booster Failure Symptoms
Hard pedal with no braking power
Longer stopping distance
Engine stalls with brakes applied
Brake pedal position higher than normal
$200
OEM (TRW) BMW Brake Master Cylinder - 34316757743
Brake Master Cylinder Failure Symptoms
Spongy Pedal Feel
Loss of brake operation
Poor brake performance
Internal fluid leaks
External fluid leaks
I found a great DIY for installing both MC and booster, but I hate brake bleeding, especially when dealing with air in the braking system. Might just take this work to a shop if cost is reasonable. Or maybe do all the parts install myself and have the vehicle towed to a shop just for brake bleeding.
https://xoutpost.com/bmw-sav-forums/...inder-diy.html