Service Procedure

A. Raise vehicle and remove both rear tire/wheel,assemblies.

B. Inspect park brake apply system for proper function, corrosion, kinks, etc. Remove nonfunctional cables.

C. Spray equalizer and both bleeder screws with Liquid Wrench (or equivalent product). Do not remove screws at this time.

D. Remove both rear calipers following the procedures in the appropriate Service Manual.

E. Remove brake pads.





F. Inspect brake pads for taper wear or excessive wear. Taper wear can be determined by taking measurements at the four points shown in the diagram below.


Calculate pad taper by subtracting the thinnest point measured from the thickest point measured.

The brake pads should be replaced if taper is greater than .080 inches.

G. Overhaul calipers as follows:


Tools Required:
* J-22269-01 Piston Installer
* J-38898 Boot Seal Installer


1. Remove shoe damping spring from end of piston.

2. Remove park brake lever.


3. Remove lever seal and antifriction washer.

4. Remove piston by turning actuator screw with lever or wrench.

NOTICE: DO NOT REUSE OLD PISTON OR OLD BALANCE SPRING.

5. Remove actuator screw by pressing on threaded end.

6. Remove shaft seal and thrust washer from actuator screw.

7. Remove old boot while being careful not to scratch the housing bore.

8. Remove piston seal, using a wood or plastic tool that will not damage the caliper bore.

9. Remove caliper mounting bolts, bushings and sleeves.

10. Remove bleeder screw.

NOTICE: If excessive resistance is encountered, use the following procedure to prevent breakage:

(A) First put a 10 mm socket over bleeder screw and tap lightly on it.

(B) If step (A) does not help, use a propane torch to heat the caliper around bleeder screw after assuring that any excess Liquid Wrench has been removed from surface. Apply heat to caliper for approximately 30 seconds to 1 minute (maximum). DO NOT USE AN ACETYLENE TORCH. Overheating the aluminum caliper could cause the bleeder screw to strip its threads.

11. Inspect caliper bore and seal groove. If necessary, use crocus cloth to polish out any light corrosion.

12. Clean all parts with GM brake parts cleaner P/N 12345754 (or equivalent).

13. Dry parts with unlubricated compressed air.

14. Blow out all passages in housing and bleeder screw.

15. Clean internal passage in bleeder screw, reinstall bleeder screw and torque to 6-9 N-m. (80-140 lb.in.).

16. Install new piston seal. Lubricate seal and bore with brake fluid.

NOTICE: Make sure that seal is not twisted.

17. Install lubricated new boot onto new piston with inside lip of boot in piston groove and boot fold toward end of piston which contacts inboard brake pad.


18. Install thrust washer on actuator screw with copper side of washer toward the piston assembly and gray surface toward the caliper housing.

19. Install lubricated shaft seal on actuator screw.

20. Install actuator screw into piston.

21. Install new balance spring into piston recess.

22. Guide lubricated piston assembly into lubricated bore of caliper.

NOTICE: Excessive force is not required to install the piston assembly into the caliper bore.

DO NOT ALLOW PISTON TO COCK IN BORE AS SEAL WILL BE DAMAGED.

23. When resistance (seal engagement) is met, rotate piston assembly back and forth to insure it is square to seal.





24. Use # J-22269-01 to install piston through piston seal. Shake tool to align piston to the seal while gently turning the jack screw to push piston through the seal to the bottom of the caliper bore. See illustration below.


25. Install lubricated antifriction washer and lever seal over end of actuator screw.

NOTICE: The sealing bead on the lever seal should be against the housing.

26. Install lever on actuator screw. Rotate lever away from stop slightly and hold while installing nut to 48 N-m (35 lb.ft.). Then, rotate lever back to contact stop.

27. Seat boot into caliper housing counter bore using new Kent-Moore tool # J-38898.

28. Install new dampening spring (included in kit) in groove on end of piston.

29. Clean, lubricate and reinstall sleeves, bushings and caliper mounting bolts.

30. Install brake shoes.

H. Reinstall calipers, per the appropriate shop manual.

I. Install hydraulic fitting and bolt, using 2 new brass washers, and torque to 33 N-m (24 lb.ft.).

J. Bleed brake system as required (power or manual), per shop manual.

K. Apply approximately 778N (175 lb.) force 3 times to the brake pedal to seat the linings.

L. Clinch outboard shoe to caliper, per shop manual.

M. Readjust park brake cable, per shop manual.

N. Reinstall wheels and tire assemblies.

0. Install Campaign Identification Label.