Backing Plate: Service and Repair
REMOVAL1. Raise and support vehicle.
2. Remove wheel cover and nut covers as required.
3. Remove tire and wheel assembly.
4. Remove drum retainers.
5. Remove drum. If drum will not come off, back off brake adjuster screw as follows:
- Pry rubber plug from rear brake backing plate inspection hole.
- Remove the brake tube-to-axle retention bracket. This will allow sufficient room for insertion of tools.
- Use a screwdriver and brake tools to disengage brake shoe adjusting lever and back off the brake adjuster screw.
6. Use an industrial vacuum cleaner such as Rotunda Brake/Clutch Service Vacuum or Rotunda Brake Parts Washer or equivalent, to remove all dust from rear brake backing plate and interior of the brake drums.
Drum And Spindle:
7. Remove hub cap grease seal from wheel hub assembly and discard rear hub cap grease seal.
8. Remove rear axle wheel hub retainer and discard.
9. Remove wheel hub from rear wheel spindle.
10. Disconnect rear brake tube from rear wheel cylinder.
11. Remove wheel cylinder retaining bolts and remove rear wheel cylinder.
12. Compress locking tangs and remove parking brake cable and conduit from brake backing plate.
13. Remove bolts retaining rear brake backing plate to rear wheel spindle. Discard bolts.
14. Remove rear brake backing plate and foam gasket.
INSTALLATION
1. Install new foam gasket on rear wheel spindle.
2. Install rear brake backing plate with new adhesive-coated retaining bolts. Tighten to 60-80 Nm (45-59 ft. lbs.).
REASSEMBLY
NOTE: Do not allow brake fluid to contact rear brake shoes and linings or they must be replaced.
1. Wipe the ends of the rear brake tubes with a clean cloth to remove any foreign matter before making connections.
2. Position rear wheel cylinder on rear brake backing plate and finger-tighten rear brake tube to rear wheel cylinder.
3. Secure rear wheel cylinder to rear brake backing plate by installing retaining bolts. Tighten bolts to 12-18 Nm (107-159 inch lbs.).
4. Using a tube nut wrench, tighten fitting nut to 16-20 Nm (12-14 ft. lbs.).
5. Apply a light coating of Silicone Brake Caliper Grease and Dielectric Compound to rear brake backing plate-brake shoe contact areas.
6. Check operation of adjuster. If it is binding, service adjuster. Refer to Brake Shoe Installation. Installation
7. Place rear brake shoes and linings and adjuster assembly on rear brake backing plate and rear wheel cylinder assembly.
8. Install two brake shoe hold-down springs and brake shoe hold-down spring pins and secure shoes.
9. Insert parking brake cable and conduit through hole in rear brake backing plate until locking tangs are firmly engaged.
10. Connect parking brake rear cable and conduit to parking brake lever.
11. Position wheel hub on rear wheel spindle.
CAUTION: To prevent damage to threads, do not use power or impact-type tools to tighten the rear axle wheel hub retainer.
12. Install rear axle wheel hub retainer and tighten to 255-345 Nm (188-254 ft. lbs.).
13. Install new rear hub cap grease seal using a 1-7/8 inch x 3/4 inch drive socket.
NOTE: The rear brake drum are self-adjusting and require a manual adjustment only after the brake shoes and linings have been replaced or when the length of the brake adjuster screw has been changed while performing some other service operation. The manual adjustment is performed with the brake drum removed, using a brake adjustment gauge. If adjustment is required, Refer to Brake Drum - Adjustments. Adjustments
NOTE: When the brake system is emptied or partially emptied, fluid may not flow from the bleeder screws during normal bleeding. It may be necessary to prime the system by performing the Master Cylinder Bleeding procedure. Service and Repair
NOTES:
- The primary and secondary (diagonal split) hydraulic brake systems are individual systems and are bled separately. Bleed longest line first on individual system being serviced, then the shorter of the two.
- During the bleeding operation, do not allow brake master cylinder reservoir to run dry. Keep master cylinder reservoir filled with High Performance DOT-3 Motor Vehicle Brake Fluid.
- Never reuse brake fluid that has been drained from the hydraulic system or has been allowed to stand in open container for an extended period of time.
BLEEDING THE WHEEL CYLINDER
1. To bleed brake system, position suitable box wrench on bleeder fitting on brake wheel cylinder. Attach rubber drain tube to bleeder fitting. The end of tube should fit snugly around bleeder fitting.
2. Submerge free end of the tube in container partially filled with clean brake fluid and loosen bleeder fitting approximately three-quarters of a turn.
3. Have assistant push brake pedal down slowly through its full travel. Close bleeder fitting and return the brake pedal to full release position.
4. Repeat Steps 2 and 3 until air bubbles cease to appear at submerged end of bleeder tube.
5. When fluid is completely free of air bubbles, secure bleeder fitting and remove bleeder tube.
6. Refill brake master cylinder reservoir after each component is bled and install master cylinder reservoir cap and gasket. Make sure diaphragm type gasket is properly positioned in master cylinder reservoir cap. When bleeding operation is completed, fluid level should be between MAX line and 4.0 mm (0.16 inch) below.
7. If necessary, Repeat this procedure for the opposite front caliper.
8. If necessary, Repeat this procedure for the opposite diagonal system.
9. After disc brake service, make sure disc brake pistons are returned to their normal positions and shoe and lining assemblies are properly seated. This is accomplished by applying brake pedal several times until normal pedal travel is established.
10. Check pedal feel. If brake pedal feels spongy repeat bleed procedure, or perform additional bleeding procedures. Refer to Brakes - Service and Repair. Service and Repair If brakes are still spongy, perform diagnosis procedure. Component Tests and General Diagnostics
NOTE: Whenever a rear brake shoe and lining is removed, check the parking brake cable and conduit tension. Refer To Parking Brake Cable - Adjustments. Adjustments
12. Install wheel and tire assembly. Tighten lug nuts to 115-142 Nm (85-104 ft. lbs.). Do not use power or impact-type tools; use a torque wrench. An Accutorq Socket on a 1/2 inch impact can be used instead of a torque wrench.