Pontiac Fiero 1984-1988 Repair Guide

Master Cylinder

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REMOVAL & INSTALLATION





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Fig. Fig. 1 The master cylinder is mounted on the power booster and retained with two nuts



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Fig. Fig. 2 Use a flare nut wrench to loosen the brake line fittings ...



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Fig. Fig. 3 ... and remove the brake lines from the master cylinder



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Fig. Fig. 4 Remove the master cylinder retaining nuts ...



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Fig. Fig. 5 ... then remove the master cylinder from its mounting

  1. Place a number of cloths or a container under the master cylinder to catch the brake fluid. Disconnect the brake tubes from the master cylinder, using a flare nut wrench only. Cap the open ends of the tubes.
  2.  

Brake fluid dissolves paint. Wipe up any spilled fluid immediately, then flush the area with clear water.

  1. Remove the two nuts attaching the master cylinder to the booster or firewall, then remove the master cylinder.
  2.  

To install:

  1. Position the master cylinder and install the retaining bolts. Torque to 22-30 ft. lbs. (29-41 Nm).
  2.  
  3. Reconnect the fluid tubes using flare nut wrenches to 17 ft. lbs. (23 Nm).
  4.  
  5. Bleed the brake system at the furthest wheel from the master cylinder first. Refer to the Brake System Bleeding procedure in this section.
  6.  

OVERHAUL





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Fig. Fig. 6 Exploded view of the master cylinder components

  1. Remove the reservoir cover and diaphragm and discard any fluid in the reservoir.
  2.  
  3. Depress the primary piston and remove the lock ring from the end of the housing.
  4.  
  5. Direct compressed air into the outlet at the blind end of the bore, and plug the other outlet to remove the primary and secondary pistons.
  6.  
  7. Remove the spring retainer and seals from the secondary piston.
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  9. Clamp the master cylinder in a vise and use an appropriate prybar to remove the plastic reservoir.
  10.  

Do not clamp on the master cylinder body. Do not attempt to remove the quick take-up valve from the body. The valve is not serviceable separately.

  1. Remove the reservoir grommets.
  2.  
  3. Inspect the master cylinder bore for corrosion. If the bore is corroded, replace the master cylinder. Do not use any abrasives on the bore.
  4.  
  5. Lubricate the new reservoir grommets with silicone brake lube and press them into the master cylinder body. Make sure the grommets are properly seated.
  6.  
  7. Lay the reservoir upside down on a flat, hard surface. Press the master cylinder body onto the reservoir using a rocking motion.
  8.  
  9. Lubricate new seals with clean brake fluid and install them on the secondary piston. Install the spring retainer.
  10.  
  11. Install the spring and secondary piston assembly into the cylinder.
  12.  
  13. Lubricate the primary piston seals with clean brake fluid. Install the primary piston, depress, and install the lock ring.
  14.  
  15. Fit the diaphragm in the reservoir cover and install on the reservoir.
  16.  

 
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