Drum Brake System: Service and Repair

Removal

1. Raise and support vehicle.
2. Mark relationship of wheel to wheel studs in bearing flange.
3. Remove wheel and tire assembly.
4. Mark relationship of drum to wheel studs in bearing flange.
5. Do not pry against splash shield when attempting to free drum. If drum is difficult to remove, proceed as follows:

a. Ensure parking brake is released.
b. Back off parking brake cable adjustment.
c. Remove adjusting hole plug from backing plate and back off adjusting screw using screwdriver.
d. Use a rubber mallet to tap gently on outer rim of brake drum and/or around inner drum diameter at bearing flange.









6. Using suitable brake spanner and remover tool No. J 38400, or equivalent, remove actuator spring by prying loop end of spring from adjuster actuator, then disconnect from web of park brake shoe.






7. Lift end of retractor spring from adjuster shoe and lining assembly. When removing retractor spring, do not overstretch spring, this will reduce its effectiveness.
8. Insert hook end of spanner and remover tool between retractor spring and adjuster shoe web, then pry or twist tool to lift end of spring out of shoe web hole. Keep fingers away from retractor spring to prevent them from being pinched.
9. Pry end of retractor spring toward axle with flat edge of spanner and remover tool until it snaps down off shoe web onto backing plate.
10. Remove adjuster shoe and lining assembly, adjuster actuator, and adjusting screw assembly. Do not remove parking brake cable from park brake lever unless park brake lever is to be replaced.
11. Lift end of retractor spring from park brake shoe and lining assembly.
12. Insert hook end of spanner and remover tool between retractor spring and adjuster shoe web, then pry or twist tool to lift end of spring out of shoe web hole. Keep fingers away from retractor spring to prevent them from being pinched.
13. Pry end of retractor spring toward axle with flat edge of spanner and remover tool until it snaps down off shoe web onto backing plate.
14. Remove park brake shoe and lining assemblies.
15. Remove retractor spring from anchor plate. If only shoe and lining are being serviced, it is not necessary to remove retractor spring.

Installation

1. Install retractor spring if removed, reinstall, hooking center spring section under tab on anchor.
2. Install park brake shoe and lining assembly as follows:

a. Position shoe and lining on backing plate assembly.






b. Using brake spanner and remover tool No. J 38400, or equivalent, pull end of retractor spring up to rest on web of brake shoe.
c. Using spanner and remover tool, pull end of retractor spring over until it snaps into slot in brake shoe.

3. Connect park brake lever to park brake shoe and lining assemblies.
4. Connect parking brake cable to park brake lever, if disconnected.






5. Install adjusting screw assembly and adjuster shoe lining assembly by engaging pivot nut with web of park brake shoe and lining and park brake lever, then position adjuster shoe and lining so shoe web engages deep slot in adjuster socket.
6. Using spanner and remover tool, install retractor spring into adjuster shoe and lining by pulling end of retractor spring up to seat on web of brake shoe, then pull end of retractor spring over until it snaps into slot in brake shoe.
7. Lubricate tab and pivot point on adjuster actuator with brake lubricant No. 1052196 or equivalent.
8. Using spanner and remover tool, spread brake shoes while working adjuster actuator into position.
9. Install actuator spring by engaging U-shaped end of spring in hole in web of park brake shoe, then using spanner and remover tool, stretch spring and engage loop end over tab on adjuster actuator.
10. Check the following for proper positioning and function of adjuster actuator:









a. Ensure adjuster actuator pivot is in shoe web slot.
b. Ensure notch in adjuster actuator is on step in adjusting screw notch.
c. Ensure arm of adjuster actuator is resting freely on star wheel teeth of adjuster screw, not trapped under teeth in a downward angle.
d. Install spanner and remover tool between upper ends of shoe and lining assemblies, then spread shoes and watch for proper rotation of star wheel.

11. Adjust service brake. Then install brake drum and wheel and tire assembly and tighten to specifications.
12. Adjust parking brake.