Answer: A. If the primary piston cup in the master cylinder is leaking pressure will not build up ahead of the primary piston to increase pressure to the rear brakes. The piston will then move forward until the spring is compressed enough to move the secondary piston. Consequently this internal leak will cause the brake pedal to slowly drop to the floor.
The driver of a vehicle with power disc/drum brakes says that the brake pedal moves slowly to the floor while maintaining pedal pressure at a stoplight. What could cause this proble…