Caliper, Rear - Service Procedure and New Tools
Bulletin: 93-5-7Date: March '93
Ref.No.: 93-111-5
Corp.Ref.No.: 335005
SUBJECT:
REAR CALIPER SERVICE PROCEDURE
MODELS AFFECTED:
1988-93 REGALS
This bulletin replaces and supersedes Bulletin 91-5-10.
CONDITION:
Some cases have been reported where:
1. It is difficult to remove and replace the park brake lever and return spring to allow retraction of the piston when servicing the rear calipers on 1988-93 Regals.
2. It is difficult to insert sleeves thru new boots when reassembling the calipers.
CORRECTION:
To eliminate these difficulties, two new tools are being supplied to dealers.
A. Piston Retraction Tool (# J-39730)
B. Seal Installation Tool (Part of 3494587 Boot Kit)
PROCEDURE:
1. Raise vehicle and remove rear wheels and tires.
2. Remove hydraulic line bracket bolt. (It is not necessary to disconnect hydraulic line from the caliper.)
3. Remove caliper mounting bolts, and remove caliper and support.
4. Remove brake pads. CAREFULLY REMOVE THE INNER PADS TO PREVENT DAMAGE TO THE PAD RETAINERS.
5. Remove sleeves. Use air chisel with Kent Moore* Tool # J-39495-1 to push each sleeve out.
6. Clean housing bores, grooves, and bolt sleeves with GM Brake Parts Cleaner - P/N 12345754 (or equivalent).
(A). Grooves should be further cleaned with a wire brush.
Use Kent Moore* Tool # J-39495-3 (or equivalent). After this, use a "seal pick" or a small screwdriver to scrape any remaining scale from the edges of the grooves.
(B). Bores should be further cleaned with a 7/8" flex hone.
Use Kent Moore* Tool # J-39495-2 (or equivalent).
NOTICE:
After brushing and honing, THOROUGHLY FLUSH the housing bores and grooves with brake parts cleaner to remove any grit remaining. The inboard grooves are not as accessible for flushing as the outboard grooves. Extra care MUST be used in flushing these areas completely. When finished, wipe with a clean cloth or paper towel to assure no grit remains.
7. IT IS NOT NECESSARY TO REPLACE THE SLEEVES. The sleeves have a hard chrome surface and are easily cleaned using the brake cleaner and a rag. Wrap a rag around the sleeve and soak the rag with brake clean. Let soak and rub the old grease off the sleeve. Do not use any abrasive materials to clean the sleeves.
NOTICE:
All contaminants must be removed from the grooves in the caliper bores to insure proper fit of boot beads.
- Some minor pitting may remain
- This is acceptable.
8. Lubricate housing grooves and bores, sleeves, and I.D. and O.D. beads of the new boots.
NOTICE:
Use all of the grease from kit for one caliper (two sleeves), and insure all grooves are full of lube.
9. Install lubricated boot into outside groove in caliper bore
10. Make sure the boot is seated in the groove by pressing the bead into the groove, and rotate the bead in the groove to insure that it is not rolled in the groove.
11. Position the new plastic installation cone on end of sleeve. (The cone will soon be included in all kits.)
12. Push lubricated sleeve in from the inside of caliper through I.D. of installed boot until the inside end of sleeve is past the groove on inside of caliper. Remove the cone from the sleeve and install it on the other end of the sleeve to ease installation thru the rear boot.
13. Install lubricated inside boot - refer to step # 12.
14. Push sleeve back the other way through the 2nd boot, remove the cone and seat the I.D. beads of both boots into sleeve grooves. Repeat for other side.
15. Cycle each pin back and forth in caliper to insure that no part of the boot is protruding from the groove in the caliper bore.
16. Clean caliper bridge where the inner pad guides (use sand paper, file. etc). Lubricate this area with a thin film of Hi-Temp grease (3M* Brake Lube/Anti-Seize Compound # 08945 or equivalent).
17. File ears on inner pad to get a total of 0.7 mm (.028") total clearance between the caliper bridge and the pad ears.
18. Retract caliper piston using the new Kent Moore* Tool # J-39730 attached to Kent Moore* Tool # J-22269-01. When retracted, make sure the grooves in the end of the piston are lined up in a vertical position to accept the inner pad retainer.
19. Reinstall brake pads and the inner pad retainer.
20. Reinstall caliper - CARE MUST BE TAKEN TO PREVENT DAMAGE TO BOOTS ON KNUCKLE AND/OR ROTOR SURFACES.
21. Reinstall hydraulic line bracket and bolt.
22. Check park brake cable adjustment.
23. Reinstall wheels and tires - USE TORQUE STICK # J-39544-15. With the publication of this bulletin, ALL dealers have at least the proper torque stick to service W-car wheel nuts.
PROCEDURE:
A torque wrench or torque stick MUST be used to insure that wheel nuts are tightened to specification. This should be done in two (2) steps using the star pattern. First, snug the nuts down by hand. Then, using the star pattern and a torque stick/wrench, tighten the wheel nuts to about half the final torque. Finally, tighten the wheel nuts to specification using the star pattern and a torque stick/wrench.
PART KITS:
P/N 3494587 BOOTS AND LUBRICANT - 1 KIT/CALIPER
Parts are currently available from GMSPO.
TOOL KIT: - Kent Moore* # J-39495 Kit Kit Includes:
A. PUNCH # J-39495-1
B. HONE # J-39495-2
C. WIRE BRUSH # J-39495-3
Kent Moore* Tool # J-39730 - Piston Retractor Tool.
Kent Moore* Tool # J-22269-01 - Accumulator Piston Compressor
Kent Moore* Tool # J-39544-15 - 19 mm (3/4") - 100 ft.lb. Torque Stick
NOTE:
Hones and wire brushes will wear out. When a new wire brush is first used, it will not enter into the bore during use. When the brush wears enough that it easily enters the bore and won't clean the grooves thoroughly, it should be replaced. When a new hone is first used, there is noticeable resistance when turned thru the bore. When this resistance is slight or the hone becomes damaged, the hone should be replaced.
Replacement wire brushes and hones are available thru the Kent Moore* Corporation - 1-800-345-2233.
* We believe these sources and their equipment to be reliable. There may be additional manufacturers of such equipment. General Motors does not endorse, indicate any preference for or assume any responsibility for the products or equipment from these firms or for any such items which may be available from other sources.
WARRANTY INFORMATION:
Labor Operation Number: T1755
Labor Time: 1.5 Hours
Parts are currently available from GMSPO.