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Power Brake Units - DELCO-Moraine Dual Diaphragm: Overhaul: Reassembly

  1. Install new check valve grommet, check valve and seal in front housing. Lubricate air valve "O" ring with power brake lubricant and install on air valve.
  2. Apply power brake lubricant to outside of floating control valve.
    NOTE: If floating control valve needs replacement, replace complete air valve push rod assembly.
  3. Position air valve end of push rod in power piston. Press down on push rod so that floating control valve bottoms on tube section of power valve.
  4. Place retainer lip on the outside of retainer installation tool (J-23175). Press retainer in until seated in power tube piston. Install filter element over push rod eye and press into power piston tube.
  5. Install snap ring in groove in air valve. Install rubber reaction bumper on end of air valve. Install air valve spring on end of air valve.
  6. Install reaction body with large hole up. Install reaction body retainer. Install reaction piston into reaction body with large diameter up.
  7. Apply power brake lubricant to the outside of the rubber reaction disc. Place disc in cavity in reaction body.
  8. Place power piston on bench with push rod up. Install assembly cone (J-28458) over push rod end of piston.
  9. Install secondary diaphragm on secondary support plate. Press raised flange on the diaphragm through the center hole on support plate. Make sure edge of support plate fits into groove in diaphragm flange.
  10. Apply power brake lubricant to the inside diameter of the secondary diaphragm. With assembly cone on power piston place secondary diaphragm and support plate on power piston and push down until it bottoms on power piston.
  11. Hold housing divider so that flange that holds primary diaphragm faces down. Place power piston bearing in the inside of divider so that extended lip of the bearing faces up.
  12. Apply power brake lubricant to inside diameter of power piston bearing. With assembly cone on power piston, hold housing divider so that flange that holds primary diaphragm faces up.
  13. Press divider down over tool and onto power piston tube until it rests against secondary diaphragm.
  14. Install primary diaphragm on primary support plate. Press raised flange on diaphragm through center hole of support plate. Make sure edge of support plate fits in groove in diaphragm flange. Apply power brake lubricant to inside diameter of diaphragm.
  15. Remove assembly cone from power piston. Fold primary diaphragm away from outside of primary support plate. Place primary diaphragm assembly over power piston. Push down until it bottoms.
  16. Fold primary diaphragm back into position on support plate. Pull outside diameter of diaphragm over flange of housing divider. Make sure bead on diaphragm is seated evenly around entire area.
  17. Position diaphragm retainer over power piston and onto diaphragm. Place assembly cone (J-28458) over power piston onto diaphragm retainer. Strike with hammer until retainer is locked on neck of power piston.
  18. Install power head silencer over neck of power piston until it rests on retainer. Apply a thin film of power brake lubricant to outside of piston rod retainer. Insert master cylinder piston rod retainer into cavity in power piston so that flat end bottoms against rubber reaction disc in bottom of cavity.
  19. Install power piston bearing in rear housing center hole so that flange of center hole in housing fits into groove of power piston bearing. Thin lip of bearing will protrude to outside of housing. Apply power brake lubricant to the inside of power piston bearing.
  20. Position housing unlock tool (J-23456) in a vise. Mount rear housing in tool and retain with two nuts. Install power piston assembly in rear housing by pressing tube through rear housing bearing.
  21. Press down until housing divider seats in rear housing and power piston bottoms against housing. Install power piston return spring over reaction body retainer.
  22. Position front housing over rear housing aligning scribe marks made during disassembly. Install spanner wrench on front housing.
  23. Tighten down on front housing and fit tangs in correct slots in rear housing. Rotate spanner wrench clockwise until front and rear housings lock.
    Fig 1: Gauging Push Rod Position
    G09317504Courtesy of NOT AVAILABLE
  24. Remove spanner wrench from front housing. Stake housing interlocks at 2 new positions, 180° apart.
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