If the brakes start dragging after 20 miles and then get rock hard again. Try reducing the length of the M/C push rod one complete turn. The M/C piston has to retract enough to uncover a port to release the brake pressure. You also need a return spring on the brake pedal so the piston can return to the original free state position. The internal M/C spring is not strong to push the pedal assembly rearward far enough. DaveW7