GM Firebird 1967-1981 Repair Guide

Brake Caliper

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REMOVAL, OVERHAUL & INSTALLATION



See Figures 1 through 5

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Fig. Fig. 1: If the caliper is being removed for overhaul or replacement, detach the brake line



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Fig. Fig. 2: Loosen the two mounting guide bolts ...



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Fig. Fig. 3: ... then remove them



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Fig. Fig. 4: Slide the caliper off of the rotor



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Fig. Fig. 5: During suspension or rotor service, hang the caliper from the frame rail with wire or cord


WARNING
Clean, high quality brake fluid is essential to the safe and proper operation of the brake system. You should always buy the highest quality brake fluid that is available. If the brake fluid becomes contaminated, drain and flush the system, then refill the master cylinder with new fluid. Never reuse any brake fluid. Any brake fluid that is removed from the system should be discarded.1967-68 Models See Figures 6 and 7



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Fig. Fig. 6: Exploded view of the four piston front brake disc caliper available as an option on some 1967-68 models



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Fig. Fig. 7: When inspecting the calipers on 1967-68 models, make certain that the piston-to-bore clearance does not exceed the values shown

  1. Raise the car and support it on jackstands.
  2.  
  3. Remove the tire and wheel assembly from the side on which the caliper is being removed.
  4.  
  5. Disconnect the brake hose at the support bracket. Tape the end of the line to prevent contamination.
  6.  
  7. Remove the cotter pin from the brake pad retaining pin and remove the pin.
  8.  
  9. Remove the brake pads and identify them as inboard or outboard if they are being reused.
  10.  
  11. Remove the U-shaped retainer from the hose fitting and pull the hose from the bracket.
  12.  
  13. Remove the two caliper retaining bolts and also the caliper from its mounting bracket.
  14.  
  15. If the caliper is to be rebuilt, continue with Step 9. Otherwise skip to Step 28 for caliper installation.
  16.  
  17. Separate the caliper halves. Remove the two O-rings from the fluid transfer holes in the caliper.
  18.  
  19. Push the piston all the way down into the caliper. Using the piston as a fulcrum, place a prytool under the steel ring in the boot and pry the boot from the caliper half.
  20.  
  21. Remove the pistons and springs, being careful not to damage the seal.
  22.  
  23. Remove the boot and seal from the piston.
  24.  
  25. Clean all metal components with clean brake fluid or denatured alcohol.
  26.  


CAUTION
Do not use gasoline, kerosene, or any other mineral-based solvent for cleaning. These solvents form an oily film on the parts which leads to fluid contamination and the deterioration of rubber parts.

  1. Blow out all fluid passages with an air hose.
  2.  
  3. Discard and replace all rubber parts.
  4.  
  5. Inspect all bores for scoring and pitting and replace as necessary. Minor flaws can be removed with very fine crocus cloth but do so with a circular motion.
  6.  
  7. Using a feeler gauge, check the clearance of the piston in its bore. If the bore is not damaged and the clearance exceeds the maximum limit, then the piston must be replaced.
  8.  
  9. Insert the seal in the piston groove nearest the flat end of the piston. The seal lip must face the large end of the piston. The lips must be in the groove and may not extend beyond.
  10.  
  11. Place the spring in the piston bore.
  12.  
  13. Coat the seal with clean brake fluid.
  14.  
  15. Install the piston assembly into the bore, being careful not to damage the seal lip on the edge of the bore.
  16.  
  17. Install the boot into the piston groove closest to the concave end of the piston.
  18.  
  19. The fold in the boot must face the seal end of the piston.
  20.  
  21. Push the pistons to the bottom of the bore and check for smooth piston movement. The end of the piston must be flush with the end of the bore. If it is not, check the installation of the seal.
  22.  
  23. Seat the piston boot so that its metal ring is even in the counterbore. The ring must be flush or below the machined face of the caliper. If the ring is seated unevenly dirt and moisture could get into the bore.
  24.  
  25. Insert the O-rings around the fluid transfer holes at both ends of the caliper halves.
  26.  
  27. Lubricate the bolts with brake fluid, connect the caliper halves, and tighten the bolts to 130 ft. lbs.
  28.  
  29. While holding in the brake pistons with a prytool, mount the caliper over the disc. Be careful not to damage the piston boots on the edge of the disc.
  30.  
  31. Install the two mounting bolts and tighten them to 130 ft. lbs.
  32.  
  33. Install the brake pads. If the same pads are being reused, return them to their original places (outboard or inboard) as marked during removal. New pads will usually have an arrow on the back indicating the direction of disc rotation. See Brake Pad Replacement for details.
  34.  
  35. Install the brake hose into the caliper, passing the female end through the support bracket.
  36.  
  37. Make sure that the tube line is clean and connect the brake line nut to the caliper.
  38.  
  39. Install the hose fitting into the support bracket and install the U-shaped retainer. Turn the steering wheel from side-to-side to make sure that the hose doesn't interfere with the tire. If it does, turn the hose end one or two points in the bracket until the interference is eliminated.
  40.  
  41. After performing the above check, install the steel tube connector and tighten it.
  42.  
  43. Bleed the brakes as instructed earlier in this section.
  44.  
  45. Install the wheels and lower the car.
  46.  

1969-81 Models See Figure 8

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Fig. Fig. 8: Exploded view of the single piston front disc brake caliper available as an option in 1969 and used as standard equipment on all 1970-81 models

  1. Perform the removal steps for pad replacement.
  2.  
  3. Disconnect the brake hose and plug the line.
  4.  
  5. Remove the U-shaped retainer from the fitting.
  6.  
  7. Pull the hose from the frame bracket and remove the caliper with the hose attached.
  8.  
  9. Clean the outside of the caliper with denatured alcohol.
  10.  
  11. Remove the brake hose and discard the copper gasket.
  12.  

For caliper overhaul, proceed with Step 7. If the caliper is being replaced, or the original caliper does not need to be serviced, skip to Step 19.

  1. Remove the brake fluid from the caliper.
  2.  
  3. Place clean rags inside the caliper opening to catch the piston when it is released.
  4.  
  5. Apply compressed air to the caliper fluid inlet hole and force the piston out of its bore. Do not blow the piston out; use just enough pressure to ease it out.
  6.  
  7. Use a prytool to pry the boot out of the caliper. Avoid scratching the bore.
  8.  
  9. Remove the piston seal from its groove in the caliper bore. Do not use a metal tool of any type for this operation.
  10.  
  11. Blow out all passages in the caliper and bleeder valve. Clean the piston and piston bore with fresh brake fluid.
  12.  
  13. Examine the piston for scoring, scratches, or corrosion. If any of these conditions exist, the piston must be replaced because it is plated and cannot be refinished.
  14.  
  15. Examine the bore for the same defects. Light rough spots may be removed by rotating crocus cloth, using finger pressure, in the bore. Do not polish with an in-and-out motion or use any other abrasive.
  16.  
  17. Lubricate the piston bore and the new rubber parts with fresh brake fluid. Position the seal in the piston bore groove.
  18.  
  19. Lubricate the piston with brake fluid and assemble the boot into the piston groove so that the fold faces the open end of the piston.
  20.  
  21. Insert the piston into the bore, taking care not to unseat the seal.
  22.  
  23. Force the piston to the bottom of the bore. (This will require a force of 50-100 lbs). Seat the boot lip around the caliper counterbore. Proper seating of the boot is very important for sealing out contaminants.
  24.  
  25. Install the brake hose into the caliper with a new copper gasket.
  26.  
  27. Lubricate the new sleeves and rubber bushings. Install the bushings in the caliper ears. Install the sleeves so that the end toward the disc pad is flush with the machined surface.
  28.  

Lubrication of the sleeves and bushings is essential to insure the proper operation of the sliding caliper design.

  1. Install the shoe support spring in the piston.
  2.  
  3. Install the disc pads in the caliper and remount the caliper on the hub, refer to the brake pad procedure, earlier in this section.
  4.  
  5. Reconnect the brake hose to the steel brake line. Install the retainer clip. Bleed the brakes, as described earlier in this section.
  6.  
  7. Replace the wheels, check the brake fluid level, check the brake pedal travel, and road-test the vehicle.
  8.  

 
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