The proportioning valve regulates the pressure to the rear brakes, reducing it under hard braking, to minimize lockup of the rear wheels. The valve can be removed after detaching the connections, and unfastening the mounting bolts. The use of a line wrench is highly recommended, especially when there are a number of connections (such as on the 1988–89 626 and MX-6). When installing, use the inlet and outlet arrows on the body of the valve to make connections properly from the master cylinder and to the wheels. Be sure to note the F marking, indicating the port leading to the front brakes. Bleed the system after completing the installation.