GM Prizm/Nova 1985-1993 Repair Guide

Master Cylinder

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REMOVAL & INSTALLATION



See Figures 1 and 2


WARNING
Be careful not to spill brake fluid on the painted surfaces of the vehicle; it will damage the paint. If spillage occurs, rinse the area immediately with water.Handle the steel brake lines very carefully. Once they are bent or kinked, they cannot be straightened.

  1. Disconnect the negative battery cable.
  2.  
  3. Clean the area at the reservoir and brake lines to prevent entry of dirt into the system.
  4.  
  5. Disconnect the wiring to the brake fluid level switch. Release the wiring from any clips.
  6.  



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Fig. Fig. 1: Removing the brake master cylinder - 1985-92



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Fig. Fig. 2: Removing the brake master cylinder - 1993 without ABS

  1. On Prizm vehicles, remove the air intake duct.
  2.  
  3. Use a syringe to remove the fluid from the reservoir. Store the fluid in a clean glass jar with a lid.
  4.  
  5. Disconnect the brake lines from the master cylinder. Plug or tape the lines immediately to keep dirt and moisture out of the system.
  6.  
  7. Remove the retaining nuts holding the master cylinder to the brake booster.
  8.  
  9. Remove the 3-way union from the booster stud on vehicles not equipped with ABS or 2-way union with ABS.
  10.  
  11. Remove the master cylinder from the studs.
  12.  
  13. Remove the seal or gasket from the booster.
  14.  
  15. When reinstalling, always use a new gasket or seal and install the master cylinder to the booster. On Nova vehicles, confirm that the UP mark on the master cylinder boot is in the correct position.
  16.  
  17. Install the 2 way or 3-way union bracket over the stud and install the retaining nuts finger tight.
  18.  
  19. Connect the brake lines to the master cylinder. Make certain each fitting is correctly threaded and tighten each fitting 1-2 turns. The job is made easier by having a small amount of movement available at the master cylinder mounting studs.
  20.  
  21. Tighten the master cylinder retaining nuts to 9.5 ft. lbs. (115 inch lbs.)
  22.  
  23. Tighten the brake line fittings to 11 ft. lbs. Do not overtighten these fittings.
  24.  
  25. On Prizm vehicles, install the air intake duct.
  26.  
  27. Connect the wiring to the brake fluid sensing switch and attach any wiring clips.
  28.  
  29. Fill the master cylinder reservoir.
  30.  
  31. Bleed the brakes.
  32.  
  33. Connect the negative battery cable
  34.  

OVERHAUL



See Figures 3 through 8

  1. Remove master cylinder from the car. Remove the cap and strainer from the reservoir.
  2.  
  3. Remove the set screw and remove the reservoir.
  4.  
  5. Mount the cylinder in a vise.
  6.  
  7. Remove the 2 grommets from the cylinder.
  8.  
  9. Using a screwdriver or similar tool, push the pistons all the way into the bore and remove the piston stopper bolt with its gasket.
  10.  
  11. Hold the piston into the bore and remove the snapring with snapring pliers.
  12.  
  13. Place a rag on 2 wooden blocks. Remove the master cylinder from the vise and tap the cylinder flange between the blocks until the piston tip protrudes.
  14.  
  15. Remove the piston by pulling it straight out.
  16.  


WARNING
If the piston is removed at an angle, the cylinder bore may become damaged.

  1. Inspect all parts of the pistons, grommets and bore for any sign of wear, cuts, corrosion or scoring. Check the inlet port and return port for obstructions. Use compressed air to clear any dirt or foreign matter from the area.
  2.  

To assemble:
  1. Apply clean brake fluid to the rubber parts of the pistons.
  2.  
  3. Insert the 2 springs and pistons straight into the bore. Do not angle them during installation.
  4.  


WARNING
Be careful not to damage the rubber lips on the pistons.



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Fig. Fig. 3: Master cylinder components - 1989-92



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Fig. Fig. 4: Removing the stopper bolt

  1. Install the snapring while pushing in the piston.
  2.  
  3. Push the pistons all the way in and install the piston stopper bolt and gasket. Tighten it to 7 ft. lbs.
  4.  
  5. Install the 2 grommets.
  6.  
  7. Install the cap and strainer onto the reservoir, then press the reservoir into position on the cylinder.
  8.  
  9. Install the set screw while pushing on the reservoir. Tighten the screw to 15 inch lbs.
  10.  

There may be a slight bit of play in the reservoir after the set screw is installed. This is normal and no washers or spacers should be installed.

  1. Reinstall the master cylinder.
  2.  



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Fig. Fig. 5: To remove the snapring, the piston must be pushed into the bore



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Fig. Fig. 6: Lightly tapping the flanges on protected blocks will release the pistons



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Fig. Fig. 7: Removing the reservoir set screw



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Fig. Fig. 8: Master cylinder reservoir assembly - 1993

 
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