Master Cylinder - Except Dual Diagonal System: Disassembly
- Drain all brake fluid from master cylinder and clean outside of master cylinder before disassembly. Remove reservoir cover and gasket. On aluminum master cylinders (with removable reservoirs) place a pry bar between master cylinder body and reservoir. Pry up until reservoir can be removed.
- On all master cylinders, place cylinder in a vise by mounting flange. Depress piston and remove stop screw, if equipped. Remove lock ring from groove in end of bore or retainer and screw. Remove rear (primary) piston assembly.CAUTION: Do not disassemble rear piston assembly or change adjustment of screw.
- Remove front (secondary) piston with air pressure. If air pressure does not work, use wire hook to pull piston out end of cylinder. Remove front piston spring if it did not come out with piston. Remove splash seal and retainer outside rear of cylinder, if they are used.
- Remove tube seats to gain access to check valves. If removal kit is not available, use one of the following methods. Thread a short screw into seat and then pry screw and seat out with a screwdriver.
- Another method is to drill a 13/64" hole through each seat. Then tap hole with a 1/4-20 tap. Screw a tubing nut into outlet. Then insert a 1/4-20 machine screw (with washer) through nut and into tube seat. Hold screw from turning. Unscrew the tubing nut to remove seat. Remove check valve and spring from drum brake outlet.