Chevrolet Citation/Omega/Phoenix/Skylark 1980-1985 Repair Guide

Master Cylinder

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REMOVAL & INSTALLATION





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Fig. Fig. 1 On vehicles that do not have power brakes, the master cylinder is mounted to the firewall



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Fig. Fig. 2 The master cylinder is mounted to the power brake booster, on vehicles equipped with power brakes



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Fig. Fig. 3 To remove the master cylinder, use a clean syringe to remove the brake fluid



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Fig. Fig. 4 Unplug the electrical connector from the master cylinder



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Fig. Fig. 5 With a shop rag placed under the lines, use a flare nut wrench to loosen ...



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Fig. Fig. 6 ... then remove the brake fluid lines from the master cylinder



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Fig. Fig. 7 Unfasten the master cylinder-to-vacuum booster retaining nuts ...



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Fig. Fig. 8 ... then remove the brake master cylinder from the vacuum booster

  1. If your car does not have power brakes, disconnect the master cylinder pushrod at the brake pedal inside the car. The pushrod is retained to the brake pedal by a clip; there is a washer under the clip, and a spring washer on the other side of the pushrod.
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  3. Use a clean syringe to remove as much of the fluid from the master cylinder as possible.
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  5. Unplug the electrical connector from the master cylinder.
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  7. 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; use a flare nut wrench if one is available. Tape over the open ends of the tubes.
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Brake fluid eats 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.
  2.  
  3. Remove the master cylinder.
  4.  

To install:

  1. Attach the master cylinder to the firewall or the booster with the nuts. Torque to 22-30 ft. lbs. (30-45 Nm).
  2.  
  3. Reconnect the pushrod to the brake pedal with non-power brakes.
  4.  
  5. Remove the tape from the lines and connect to the master cylinder. Torque to 10-15 ft. lbs. (13-20 Nm). Connect the electrical lead.
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  7. Bleed the brakes.
  8.  

OVERHAUL





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Fig. Fig. 9 Exploded view of the master cylinder assembly



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Fig. Fig. 10 Use a large prybar to carefully separate the reservoir from the master cylinder



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Fig. Fig. 11 Install the master cylinder body to the reservoir using a rocking motion

This is a tedious, time-consuming job. You can save yourself a lot of trouble by buying a rebuilt master cylinder from your dealer or parts supply house. The small difference in price between a rebuilding kit and a rebuilt part usually makes it more economical, in terms of time and work, to buy the rebuilt part.

  1. Remove the master cylinder.
  2.  
  3. Remove the reservoir cover and drain the fluid.
  4.  
  5. Remove the pushrod and rubber boot on non-power models.
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  7. Unbolt the proportioners and failure warning switch from the side of the master cylinder body. Discard the O-rings found under the proportioners. Use new ones on installation. There may or may not be an O-ring under the original equipment failure warning switch. If there is, discard it. In either case, use an O-ring upon assembly.
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  9. Clamp the master cylinder body in a vise, taking care not to crush it. Depress the primary piston with a wooden dowel and remove the lock ring with a pair of snapring pliers.
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  11. The primary and secondary pistons can be removed by applying compressed air into one of the outlets at the end of the cylinder and plugging the other three outlets. The primary piston must be replaced as an assembly if the seals are bad. The secondary piston seals are replaceable. Install these new seals with the lips facing outwards.
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  13. Inspect the bore for corrosion. If any corrosion is evident, the master cylinder body must be replaced. Do not attempt to polish the bore with crocus cloth, sandpaper, or anything else. The body is aluminum; polishing the bore won't work.
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  15. To remove the failure warning switch piston assembly, remove the allen head plug from the end of the bore and withdraw the assembly with a pair of needlenose pliers. The switch piston assembly seals are replacable.
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  17. The reservoir can be removed from the master cylinder body if necessary. Clamp the body in a vise by its mounting flange. Use a prybar to remove the reservoir. If the reservoir is removed, remove the reservoir grommets and discard them. The quick takeup valves under the grommets are accessible after the retaining snaprings are removed. Use snapring pliers; no other tool will work.
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  19. Clean all parts in denatured alcohol and allow to air dry. Do not use anything else to clean, and do not wipe dry with a rag, which will leave bits of lint behind. Inspect all parts for corrosion or wear. Generally, it is best to replace all rubber parts whenever the master cylinder is disassembled, and replace any metal part which shows any sign whatsoever of wear or corrosion.
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  21. Lubricate all parts with clean brake fluid before assembly.
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  23. Install the quick take-up valves into the master cylinder body and secure with the snaprings. Make sure the snaprings are properly seated in their grooves. Lubricate the new reservoir grommets with clean brake fluid and press them into the master cylinder.
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  25. Install the reservoir into the grommets by placing the reservoir on its lid and pressing the master cylinder body down onto it with a rocking motion.
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  27. Lubricate the switch piston assembly with clean brake fluid. Install new O-rings and retainers on the piston. Install the piston assembly into the master cylinder and secure with the plug, using a new O-ring on the plug. Torque is 40-140 inch lbs. (5-16 Nm).
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  29. Assemble the new secondary piston seals onto the piston. Lubricate the parts with clean brake fluid, then install the spring, spring retainer and secondary piston into the cylinder. Install the primary piston, depress, and install the lock ring.
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  31. Install new O-rings on the proportioners and the failure warning switch. Install the proportioners and torque to 18-30 ft. lbs. (25-40 Nm). Install the failure warning switch and torque to 15-50 in. lbs. (2-6 Nm).
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  33. Clamp the master cylinder body upright into a vise by one of the mounting flanges. Fill the reservoir with fresh brake fluid. Pump the piston with a dowel until fluid squirts from the outlet ports. Continue pumping until the expelled fluid is free of air bubbles.
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  35. Install the master cylinder, and bleed the brakes. Check the brake system for proper operation. Do not move the car until a "hard" brake pedal is obtained and the brake system has been thoroughly checked for soundness.
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