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Home >> GMC >> 1981 >> Forward Control 4.8L Eng VIN T, Standard Trans >> Repair and Diagnosis (Single Page) >> Brakes >> Mechanical - Hydraulic >> Power Brake Units - DELCO-Moraine Tandem Diaphragm >> Overhaul >> Power Brake Unit >> Disassembly

Power Brake Unit: Disassembly

  1. Remove pushrod boot, silencer, front housing seal, grommet and vacuum check valve.
  2. Scribe a mark on front and rear housing for reassembly reference. Attach front housing to suitable holding fixture (J-22805-01).
  3. Place spanner wrench (J-9504) over rear housing studs, press down, and turn counterclockwise to unlock housings. Carefully separate housings.
  4. Remove power piston group, power piston return spring, and power piston bearing. Remove piston rod, reaction retainer and power head silencer.
  5. Grasp assembly at outside edge of divider and diaphragms. Hold with pushrod down against a hard surface. Use a slight force or impact to dislodge diaphragm retainer.
  6. Remove primary diaphragm, primary support plate, secondary power piston bearing, housing divider, secondary support plate and diaphragm and power piston assembly.