GM S10/S15/Sonoma Pick-Ups 1982-1993 Repair Manual

Brake Caliper

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REMOVAL & INSTALLATION



See Figures 1 through 5

  1. If the fluid reservoir is full, siphon off about 2 / 3 of the brake fluid from the master cylinder reservoirs in order to prevent the possibility of spillage when the caliper pistons are bottomed. A common kitchen turkey baster may also be used to remove brake fluid, but make sure the tool is clean before inserting it in the reservoir.
  2.  
  3. Raise and support the front of the vehicle safely using jackstands.
  4.  
  5. Remove the front tire and wheel assemblies.
  6.  
  7. If the brake pads are being replaced (and the caliper is NOT being overhauled), install a C-clamp on the caliper so that the solid frame side of the clamp rests against the back of the caliper and the driving screw end rests against the metal part (center backing plate) of the outboard pad. Tighten the clamp until the caliper moves sufficiently to bottom the piston in its bore, then remove the clamp.
  8.  
  9. Remove the two Allen head caliper mounting bolts from the back of the caliper. If the caliper is not being completely remove from the vehicle, remove it from the mounting bracket and support it from the suspension using a coat hanger or length of wire. DO NOT allow the hose to be stretched, twisted, kinked or otherwise damaged.
  10.  
  11. If the caliper is being completely removed from the vehicle, disconnect the flexible brake hose-to-caliper banjo-bolt, discard the pressure fitting washers (they must be replaced with new ones during assembly), then remove the brake caliper from the vehicle and place it on a work bench.
  12.  
  13. To inspect the caliper assembly, perform the following procedures:
    1. Check the inside of the caliper assembly for pitting or scoring. If heavy scoring or pitting is present, caliper replacement is recommended.
    2.  
    3. Check the mounting bolts and sleeves for signs of corrosion; if necessary, replace the bolts.
    4.  

  14.  

If the mounting bolts have signs of corrosion, DO NOT attempt to polish away the corrosion. Instead the bolts must be replaced to assure proper caliper sliding and prevent the possibility of brake drag or locking.

To install:
  1. Lubricate and position the caliper bushings and sleeves. Apply Delco® silicone lube or equivalent to lubricate the mounting bolts.
  2.  
  3. With both pads installed to the caliper, place the caliper over the disc, lining up the hole in the caliper ears with the holes in the mounting bracket.
  4.  
  5. If the caliper was completely removed, install the flexible hose to the caliper and secure using the banjo bolt and new washers. Make sure that the brake hose is not twisted or kinked, then tighten the bolt to 32 ft. lbs. (44 Nm).
  6.  
  7. Carefully insert the mounting bolts through the bracket and caliper (bushing and sleeves), then tighten to 37 ft. lbs. (7 Nm).
  8.  
  9. Pump the brake pedal a few times to seat the linings against the rotors.
  10.  
  11. Use a pair of channel lock pliers to compress the pad ears so no clearance exists between the pad ears and the caliper.
  12.  
  13. Check the clearance between the caliper and steering knuckle. Clearance at each end of the caliper should be measured individually and the results added together. Clearance should not exceed 0.010-0.024 in. (0.026-0.60mm).
  14.  
  15. Install the wheels, then remove the jackstands and carefully lower the vehicle.
  16.  
  17. Check and refill the master cylinder reservoirs with brake fluid.
  18.  


CAUTION
DO NOT attempt to move the vehicle until a firm brake pedal is obtained.

  1. Properly bleed the hydraulic brake system. If only a caliper fitting was disconnected, bleeding of the entire system should not be required. Bleed air from the system at the caliper that was disconnected. Check the system for proper operation. If air remains in the system, bleeding at all points in the system may be required.
  2.  

OVERHAUL



See Figures 6, 7, 8 and 9

  1. Remove the brake caliper from the vehicle.
  2.  
  3. Remove the inlet fitting from the brake caliper and drain all brake fluid to help cut down on the inevitable mess.
  4.  
  5. Position the caliper on a work bench and place clean shop towel in the caliper opening. Use a small amount of compressed air, force the piston from it's bore.
  6.  


CAUTION
DO NOT apply too much air pressure to the bore, for the piston may jump out, causing damage to the piston and/or the operator. Be ABSOLUTELY SURE to keep your fingers away from the piston while air is being applied.

Click image to see an enlarged view

Fig. Fig. 1: Exploded view of a common caliper assembly



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Fig. Fig. 2: Remove the caliper assembly from the vehicle and place it on a clean working surface



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Fig. Fig. 3: Use compressed air to push the piston out against a clean rag but KEEP YOUR FINGERS CLEAR



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Fig. Fig. 4: Grasp the piston and remove it from the caliper bore



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Fig. Fig. 5: Remove the boot from the caliper housing, taking care not to score or damage the bore



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Fig. Fig. 6: USE EXTREME caution when removing the piston seal; DO NOT scratch the caliper bore



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Fig. Fig. 7: If necessary, remove the bleeder valve from the caliper



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Fig. Fig. 8: Exploded view of the caliper components



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Fig. Fig. 9: During assembly use a suitable piston boot driver to properly install the boot to the housing


  1. Remove and discard the piston boot and seal. Be careful not to scratch the bore. Use of a metal tool is NOT recommended when removing the boot and the seal because of the possibility of scoring and damaging the bore.
  2.  
  3. Inspect the piston and the caliper bore for damage or corrosion. Replace the caliper and/or the piston (if necessary).
  4.  
  5. Remove the bleeder screw and it's rubber cap.
  6.  
  7. Clean all of the parts with non-mineral based solvent and blow dry with compressed air. All rubber parts should be replaced with those in the brake service kit.
  8.  
  9. Inspect the guide pins for corrosion, replace them (if necessary). When installing the guide pins, coat them with a silicone lubricant.
  10.  

To assemble:
  1. Lubricate the piston, caliper and seal with clean brake fluid.
  2.  
  3. Install the seal into the caliper bore making sure it is not twisted in the caliper bore groove.
  4.  
  5. Install the boot onto the piston, then position the piston into the caliper bore.
  6.  
  7. Bottom the piston into the bore, then secure the boot to the housing using J-26267 or an equivalent piston seal installer tool.
  8.  
  9. Install the bleeder valve and tighten to 62 inch lbs. (7 Nm).
  10.  
  11. Install the caliper to the vehicle and properly bleed the hydraulic brake system.
  12.  

 
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