Buick Regal 1997-2000

Brake Caliper

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Overhaul



  1. Remove the rear caliper using the procedures found in this section.
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  3. With the caliper removed from the vehicle, place it on a clean work surface. Brake fluid in the caliper will tend to run out onto the work surface, where it can damage painted components. Placing some cardboard or other disposable covering on the work surface may save time at cleanup.
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  5. Perform a visual inspection. If the caliper has an obvious crack or shows signs of collision damage, it may not be reusable. Check the tapped openings where the mounting bolts thread. In some cases, the threads can be damaged from corrosion or were cross-threaded during previous brake work. Sometimes threaded inserts can be used to save a caliper, but generally, if the caliper body shows signs of abuse, it should be replaced.
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CAUTION
Do not place your fingers in front of the caliper piston in an attempt to catch or 'protect' the piston when applying compressed air. The piston come out with a surprising amount of force and can serious injure your fingers. In addition, wear eye protection because the brake fluid in the caliper will tend to spray when shop air is applied.

  1. Use clean shop cloths to pad the inside of the brake caliper during piston removal. Use just enough shop air to ease the piston out of the bore. If the piston is simply blown out, even with padding provided, it may be damaged. The piston will come out through the piston dust boot.
    1. An alternate method for piston removal on these calipers is to use a spanner-type tool (or careful work with pliers) in the slots in the end of the piston to thread the piston out of the caliper.
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  3. Inspect the piston for scoring, nicks corrosion, and/or worn or damaged chrome plating. Replace the piston, if any of these conditions are found.
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  5. Remove the caliper boot, being careful not to scratch the housing bore. Look for a boot retaining ring. Use a small prying tool to pry up one end of the boot ring. Work the boot ring out of the caliper groove.
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WARNING
Do not use a metal tool to remove the piston seals. Metal tools may damage the caliper bores or piston seal grooves.

  1. Remove the piston seal from the groove in the caliper bore, using a small wood or plastic tool. These seals are usually "square profile" O-rings.
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  3. Remove the bleeder valve screw.
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  5. Remove the lever return spring only if replacement is required. Use a small prytool to disengage the return spring from the parking brake lever. Then unhook the spring from the stopper pin.
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  7. Remove the caliper mounting bolt (also called a 'slider pin') boots and sleeves from the caliper.
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  9. Inspect the caliper bores, pistons and mounting threads for scoring or excessive wear.
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  11. Use crocus cloth (an extremely fine abrasive cloth) to polish out light corrosion from the piston and bore. If the crocus cloth cannot remove the corrosion, do not use a more coarse abrasive. The caliper must be replaced.
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  13. Clean all parts with denatured alcohol and dry with compressed air. Inspect all parts for damage and replace as necessary.
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Fig. Exploded view of a rear disc brake caliper equipped with built-in parking brake mechanism



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Fig. Using an air gun to coax the piston from the caliper bore



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Fig. Removing the piston boot ring



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Fig. Removing/installing the parking brake lever return spring



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Fig. Cross-sectional view of the piston, showing the proper position of the dust boot on the piston

  1. Lubricate the pin sleeve with silicone grease. Install the pin bolt and pin sleeve to the caliper support. Tighten the bolt to 20 ft. lbs. (27 Nm).
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  3. Lubricate the sleeve boot with silicone grease to ease installation. Compress the lip sleeve boot and push it all the way through the caliper body until the lip emerges and seats on the inboard face of the caliper ear.
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  5. Lubricate the sleeve with silicone grease to ease assembly. Push the bolt sleeve in through the lip end of the boot until the boot seats in the sleeve groove at the other end.
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  7. Install the bolt boot onto the caliper body.
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  9. Install the pin boot over the pin sleeve (installed on the caliper support).
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  11. If removed, install a new lever return spring. Position the spring with the hook end around the stopper pin, then pry the other end of the spring over the lever.
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  13. Lightly lubricate the bleeder valve screw with anti-seize compound and install finger tight. Final tightening will be done after the system is bled.
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  15. Lubricate a new piston seal with clean brake fluid, then install the seal. Make sure the seal is not twisted.
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  17. Install the piston boot onto the piston assembly.
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  19. Lubricate the piston assembly with clean brake fluid, then install the piston and boot into the bore of the caliper body assembly. Start the piston in by hand, then thread it into the bottom of the caliper bore using a suitable spanner-type tool into the slots in the end of the piston assembly.
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  21. Install the boot ring. Make sure the outside edge of the piston boot is smoothly seated in the counterbore or the caliper body assembly. Work the boot ring into the groove near the open end of the caliper bore, being careful not to pinch the piston boot between the boot ring and the caliper body.
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  23. After installing the ring, lift the inner edge of the boot next to the piston assembly and press out any trapped air. The boot must lie flat.
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  25. Install the caliper as outlined earlier in this section. Make sure to properly bleed the brake system.
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Removal & Installation



With Built-In Parking Brake Mechanism
  1. Using a suction gun, remove approximately 2 / 3 of the brake fluid from the master cylinder. The reason for this is that the caliper pistons must be pushed back into their bores so the caliper can be removed from the rotor. This could cause the brake fluid to overflow from the reservoir onto painted surfaces or wiring.
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  3. Raise and safely support the vehicle on safety stands.
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  5. Mark the relationship of the wheel to the hub so it can later be installed in the same relationship. This helps retain the balance of the rotating assembly.
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  7. Remove the rear tire and wheel assembly. Install two wheel lug nuts to keep the rotor on the hub.
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  9. Disconnect the brake line to the caliper. Plug the opening so all of the brake fluid does not drain from the master cylinder reservoir.
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  11. Remove the parking brake cable from the parking brake lever. Lift up on on