Power Brake Unit: Disassembly
- Remove master cylinder and check valve from power unit. Place power unit in a vise with push rod up.
- Scribe alignment marks on front and rear shells to assure reassembly in original position. Remove clevis, lock nut, and dust boot from rear shell.CAUTION: Separate front and rear shells carefully. Spring tension may cause rear shell to release quickly.
- Attach a bar and plate tool to rear shell mounting studs. Press down on tool while rotating it clockwise to unlock rear shell.
- Lift rear shell assembly from power unit, remove air silencer retainer, and separate diaphragm from power piston assembly. Remove valve rod with plunger assembly from rear shell.
- Remove lock plate and press valve rod in to remove valve retainer key. Remove valve rod and plunger assembly. Remove air silencer and filter.NOTE: Service valve rod plungers as an assembly.
- Remove retainer and bearing. Never remove rear seal from rear shell unless seal is defective and a new one is available. Remove push rod, front seal, and support plate.