• On Disc front, Drum rear combinations with a single master cylinder, be sure to remove the residual check valve, or purchase a master cylinder without a check valve. You must then install an in-line residual check valve in the line to the rear drum brakes. The valve should be installed on the brake side of the proportioning valve as shown in the diagram.
• When using a dual master cylinder with Disc front, Drum rear combinations you won't need to remove the residual check valve as it only applies pressure to the rear brake line. On dual master cylinders, the large reservoir side is for the disc brakes, and the small reservoir side is for the drum brakes.
• Do not use a residual pressure valve with 4 wheel Disc brake systems. The residual pressure will cause the calipers to drag.
• An adjustable Proportioning valve allows you to balance the pressure between the front and rear brakes for smooth safe stops. This is a must for disc/drum combinations, as disc brakes require considerably more pressure to operate than drum brakes. Without a properly adjusted proportioning valve, the drum brakes will lock up before the discs do which can result in handling problems. Proportioning valves are also useful on 4-wheel disc or 4-wheel drum brake systems, giving you the ability to compensate for tire size differences, weight distribution, etc.
• Make sure that the bleeder valves on the calipers and the power booster point up when installed. Air cannot be fully bled from the system unless the valves are installed in the up position.
• If you do not intend to use a power booster, we recommend that you use a dual master cylinder.