[dsraven]

the rubber bumpers also set the brake pedal height so it is the same with each release of the pedal. this allows the master cylinder pushrod to be adjusted correctly so the internals in the master will allow the cylinder to A) release the pressure in the system properly after the brake pedal is released. this is important because otherwise the brakes may drag when the fluid gets hot and expands. B) this allows the piston to retract far enough so the brakes can be "pumped" to make up for fluid loss or out of adjustment drum brakes