Power Brake Units - DELCO-Moraine Single Diaphragm: Overhaul: Disassembly

Scribe mark housings (for reassembly), then remove master cylinder. Attach suitable separator tool and wrench (J-9504 and J-22805 or J-22893), press down and turn counterclockwise to separate housings. If necessary, tap lightly with plastic hammer to assist separation.
NOTE: Do not put pressure on plastic power piston extension.

Lift rear housing assembly from unit. Remove clevis, lock nut, silencer retainer, and silencer from push rod. Separate power piston assembly and seal from rear housing.
Remove air filter from power piston neck. Pry lock ring off power piston. Remove reaction retainer, piston rod, reaction plate, three reaction levers, air valve springs, small reaction bumper, and air valve spring retainer. Position suitable support plate tool (J-21524) in vise and in notches of support plate. Grip steel plate under diaphragm, press down and turn counterclockwise until plate separates from power piston. Remove air valve snap ring. Using rod (not exceeding 1/2" diameter), press air valve assembly from power piston.
NOTE: Air valve (floating control valve) push rod assembly is serviced as complete unit. New assembly should always be installed if original is removed from power piston.
Remove power piston return spring from front housing. Remove front housing seal. If defective, remove check valve and grommet. Push master cylinder push rod from center of reaction retainer. Remove "O" ring from master cylinder push rod.