Review on Cardone 10 1388 Remanufactured Master Cylinder by Jerry Amos

Residual Pressure Valves are NOT installed in the front or rear ports. These residual valves are required for drum brakes and the OEM has the required valves. This does not work immediately on any car with drum brakes. To use this you either need to install them in the master cylinder or weight them down in the outer ones. (You can tell if there is a valve by carefully inserting a toothpick into the opening. If it goes far enough, the valve isn't there.