BENDIX/DELCO-Moraine Dual Piston Master Cylinder: Description

All master cylinders are single cylinder with front and rear pistons. Master cylinders can have divided or common reservoirs that are integral with the piston cylinder. Aluminum master cylinders have reservoirs that are removable from piston cylinders. Front piston is operated by rear piston. In a divided reservoir, the larger reservoir feeds the disc brakes. This is because the pistons used on disc brakes are larger than wheel cylinders used on drum brakes. A residual pressure valve is located in the master cylinder under outlet seat for drum brakes. This keeps a small amount of pressure in drum brake circuit.

NOTE: Chrysler models do not use a residual valve for rear drum brakes.

Disc brake outlet does not have a residual pressure valve.

NOTE: Disc brakes must not have any residual pressure or they will lock up.

On some master cylinders a stop screw is screwed in from outside of cylinder. This stop screw limits return stroke of front piston. Some master cylinders have one outlet on bottom and one on the side. A bleeder screw on these master cylinders allows trapped air to be released.