Front Brake Caliper Overhaul JE5, JL55

Warning: Refer to Brake Fluid Irritant Warning in the Preface section.

Warning: Refer to Brake Dust Warning in the Preface section.

Caution: Refer to Brake Fluid Effects on Paint and Electrical Components Caution in the Preface section.

Warning: Do not place fingers in front of the caliper piston(s) in an attempt to catch or protect it when applying compressed air. The piston(s) can fly out with force and could result in serious bodily injury.

Note: 

1. Remove the brake caliper from the vehicle. Refer to Front Brake Caliper Replacement.
2. Drain the brake fluid from the brake caliper.




Caution: Use clean cloths to pad interior of caliper housing during piston removal. Use just enough air to ease the pistons out of the bores. If the pistons are blown out, even with the padding provided, it may be damaged.

3. Place a 25 mm (1 in) block of wood between the caliper and the piston.
4. Install a large C-clamp over the body of the brake caliper with the C-clamp ends against the rear of the caliper body and against the block of wood.
5. Carefully remove the brake caliper piston by directing low pressure compressed air into the brake caliper inlet hole.
6. Remove the C-clamp from the caliper.
7. Remove the block of wood from the caliper.
8. Install clean cloths to pad the interior of the caliper housing between the remaining caliper piston and the caliper body.
9. To cover the open caliper bore place a 25 mm (1 in) block of wood between the caliper body and the brake caliper dust boot seal.
10. Install a large C-clamp over the body of the brake caliper with the C-clamp ends against the rear of the caliper body and against the block of wood.
11. Carefully remove the brake caliper piston by directing low pressure compressed air into the brake caliper inlet hole.
12. Remove the C-clamp form the caliper.
13. Remove the block of wood from the caliper.



14. Remove the piston dust boot seals (2)  from the seal counter-bores in the brake caliper and discard the boot seals.
15. Using a small wooden or plastic tool, remove the piston seals (1) from the brake caliper bores and discard the piston seals.



16. Remove the brake caliper bleeder valve cap.
17. Remove the brake caliper bleeder valve (1).
18. Remove the brake caliper bleeder valve seal (2) and discard.




Note: Do not use abrasives to clean the brake caliper pistons.

19. Inspect the brake caliper mounting bracket guide surfaces for corrosion and wear. Remove and replace the brake caliper mounting bracket if damaged or worn.
20. Clean the brake caliper piston bores and seal counter-bores with denatured alcohol, or equivalent.
21. Clean the brake caliper pistons with denatured alcohol, or equivalent.
22. Dry the caliper piston bores and counter-bores with non-lubricated, filtered air.
23. Dry the brake caliper pistons with non-lubricated, filtered air.
24. Inspect the caliper bores for cracks, scoring, pitting, excessive corrosion.
25. If light corrosion is present in the caliper bores, attempt to remove the imperfection with a fine emery paper. If the imperfection cannot be removed, replace the caliper assembly.
26. If cracks, scoring, pitting, and excessive corrosion are present in the caliper bores, replace the caliper assembly.
27. Inspect the caliper pistons for cracks, scoring, and/or damage. Replace the caliper pistons if any of these conditions exist.

1. Install the valve stem seal (2) over the threaded end of the bleeder valve (1).

Caution: Refer to Fastener Caution in the Preface section.

2. Install the brake caliper bleeder valve (1).

Tighten
Tighten the bleeder valve to 14 N·m (124 lb in).

3. Install the brake caliper bleeder valve cap.



4. Lubricate the new piston seals (1) with Delco Supreme 11®, GM P/N 12377967 (Canadian P/N 992667) or equivalent DOT-3 brake fluid from a clean, sealed brake fluid container.
5. Install lubricated piston seals into the brake caliper bore seal grooves.
6. Make sure the seals are not twisted.



7. Install the piston dust boot (2) over the end of the piston (3) so that the fold will face toward the brake caliper housing piston bore opening.
8. Seat the caliper dust boot into the brake caliper bore groove (1) and slide the piston into the brake caliper bore.



9. Using your fingers, carefully push the piston to the bottom of the brake caliper bore.
10. Ensure the caliper dust boot is properly seated into the piston groove and into the groove in the brake caliper bore.
11. Repeat steps 5 - 10 for the remaining piston.
12. Install the brake caliper to the vehicle. Refer to Front Brake Caliper Replacement.

Front Brake Caliper Overhaul J56

Warning: Refer to Brake Fluid Irritant Warning in the Preface section.

Caution: Refer to Brake Fluid Effects on Paint and Electrical Components Caution in the Preface section.

Caution: Do not remove the caliper external crossover tube or separate the 2 caliper halves. If the crossover tube and/or the caliper halves are separated, corrosion and damage to the caliper may result.

Caution: This brake caliper is coated with a specialized paint. Use care when handling and servicing to ensure the paint does not get chipped or scratched. Clean any brake fluid from painted surfaces with denatured alcohol, or equivalent, as soon as possible.

Note: 

Warning: Do not place fingers in front of the caliper piston(s) in an attempt to catch or protect it when applying compressed air. The piston(s) can fly out with force and could result in serious bodily injury.

Caution: Use clean cloths to pad interior of caliper housing during piston removal. Use just enough air to ease the pistons out of the bores. If the pistons are blown out, even with the padding provided, it may be damaged.

Note: It will be necessary to fabricate one or more blocks of wood to the following dimensions to be used during this procedure:

1. Remove the brake caliper from the vehicle. Refer to Front Brake Caliper Replacement.
2. Drain the brake fluid from the brake caliper.
3. Place the caliper in a vise using plastic vise caps or suitable material to protect the caliper mounting bosses from the vise jaws.



4. Place a discarded brake pad or the fabricated 127 mm (5 in) long block of wood over 2 adjoining piston bores and secure in place with a non-marring C-clamp.
5. Place the fabricated 51 mm (2 in) long block of wood over one of the opposing piston bores and secure it in place with a non-marring C-clamp or suitable brake pad spreader tools.
6. Use clean cloths or the other fabricated 127 mm (5 in) long block of wood to pad the interior of caliper housing during removal of the piston.



7. Carefully remove the brake caliper piston (1) by directing low pressure compressed air into the brake caliper inlet hole.
8. Move the fabricated 51 mm (2 in) long block of wood over the emptied piston bore and secure it in place with a non-marring C-clamp or suitable brake pad spreader tools.
9. Move the clean cloths or the other fabricated 127 mm (5 in) long block of wood to pad the interior of caliper housing during the removal of the piston.
10. Carefully remove the brake caliper piston by directing low pressure compressed air into the brake caliper inlet hole.
11. Repeat steps 4 through 10 for the opposite side of the caliper.
12. Using care to not scratch or mar the painted surfaces or piston bore, remove all the dust boot seals (2) using a flat-bladed tool. Discard the dust boot seals.
13. Using wooden or plastic tool, remove the piston seals (3) from the piston bores. Discard the piston seals.
14. Remove both brake caliper bleeder caps and valves.
15. Remove the caliper from the vise and clean the entire caliper with denatured alcohol, or equivalent.
16. Dry the caliper piston bores with non-lubricated filtered air. Make sure the external crossover pipe and the internal fluid ports are clean and free of obstructions.
17. Inspect the caliper cylinder bores and piston seal counter-bores for scratches, cracks, pitting, and/or corrosion.

Note: Do not clean the caliper piston bores by honing or cleaning with abrasives.

18. If the caliper piston bores are scratched, cracked, or pitted, or if corrosion cannot be cleaned with denatured alcohol, replace the caliper assembly.

1. Assemble the brake caliper piston (1) to the dust boot seal (2). Ensure the dust boot seal is properly seated on the piston, in the dust boot seal groove.
2. Lubricate the new piston seals (3) with GM approved brake fluid from a clean, sealed brake fluid container.
3. Install the lubricated new piston seals into the brake caliper bore seal grooves. Ensure sure the seals are not twisted.
4. Apply a thin coat of GM approved brake fluid from a clean, sealed brake fluid container, onto the caliper piston bores and the outer surface of the caliper pistons.
5. Install the piston and dust boot assemblies into the correct caliper bores. Press the pistons and dust boot seals all the way in by hand.
6. Place a clean, discarded brake pad or the fabricated 127 mm (5 in) long block of wood over adjoining piston bores and apply light pressure with non-marring C-clamp. This will ensure the dust boots and pistons are fully seated into the caliper.
7. Repeat step 6 for the opposite pistons.

Caution: Refer to Fastener Caution in the Preface section.

8. Install the brake caliper bleeder valves and tighten to  14 N·m (124 lb in).
9. Install the brake caliper bleeder valve caps.
10. Install the caliper to the vehicle. Refer to Front Brake Caliper Replacement.