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SECTION 4E

REAR DRUM BRAKES

SPECIFICATIONS

General Specifcations

Application
Millimeters
Inches
Brake Drums:
.
.
Inside Diameter
200.00
7.87
Maximum Revore Diameter
201.00
7.91
Out-to-Round
0.04
0.001
Wheel Cylinder Diameter:
.
.
Rear
20.64
0.81

Fastener Tightening Specifications

Application
N•m
Lb-Ft
Lb-In
Brake Line
16
12
-
Brake Wheel Hub/Backing Plate-to-Rear Axle Nuts
28
21
-
Rear Hub Caulking Nut
190
140
-
Wheel Cylinder-to-Backing Plate Bolt
8
-
71

DIAGNOSIS

Lining Inspection

  1. Raise and suitably support the vehicle.
  2. Remove the wheel. Refer to Section 2E, Tires and Wheels.
  3. Release the parking brake.
  4. Remove the drum. Refer to " Drum" in this section.
  5. Measure the lining thickness. The minimum lining thickness is 0.5 mm (0.02 inch).

Caution : To avoid injury when servicing brake parts, do not create dust by grinding or sanding the brake linings or by cleaning the wheel brake parts with a dry brush or with compressed air.

Important : Replace the shoe and lining assembly in axle sets only.

  1. Install the drum, if removed.
  2. Install the wheel, if removed. Refer to Section 2E, Tires and Wheels.
  3. Lower the vehicle.

Drums

Whenever brake drums are removed, they should be thoroughly cleaned and inspected to see if the drums are cracked, scored, deeply grooved, or beyond the specified out-of-round limit.

MAINTENANCE AND REPAIR

ON-VEHICLE SERVICE



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Brake Adjustment

Removal Procedure

  1. Release the parking brake.
  2. Operate the brake at least 10 times until the jumping of the adjustment spring on the adjustment nut can no longer be heard on either brake drum.
  3. Raise and suitably support the vehicle.
  4. Remove the rear wheels. Refer to Section 2E, Tires and Wheels. Mark the position of the wheels relative to the wheel hubs.
  5. Remove the caulking nut.
  6. Remove the brake drum.


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  8. Using the rear brake adjuster nut, turn the adjuster assembly in until there is a sufficient amount of drag on the brake drum.
  9. Make sure that the parking brake lever stops are against the edge of the shoe web. If they are not, loosen the parking brake cable at the equalizer. Refer to Section 4G, Parking Brake.


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Installation Procedure

  1. Position the rear brake drum. Fasten the rear hub caulking nut.
  2. Tighten
    Tighten the one-piece rear hub caulking nut to 190 N•m (140 lb-ft).

  3. Install the rear wheels. Refer to Section 2E, Tires and Wheels. Mark the position of the wheels relative to the wheel hubs.
  4. Important : The brake pedal must be operated more than 10 times. When the clicking can no longer be heard, the clearance between the brake shoe and drum is adjusted.

  5. Apply the foot brake several times until the clicking of the adjustment actuator can no longer be heard.
  6. Adjust the parking brake. Refer to Section 4G, Parking Brake.


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Shoe and Lining

Removal Procedure

  1. Raise and suitably support the vehicle.
  2. Remove the rear wheels. Refer to Section 2E, Tires and Wheels. Mark the position of the wheels relative to the wheel hubs.
  3. Mark the position of the wheels relative to the wheel hub.
  4. Loosen the parking brake cable. Refer to Section 4G, Parking Brake. Mark the position of the wheels relative to the wheel hubs.
  5. Remove the drum caulkimg nut and the brake drum.


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  7. Loosen the leading shoe hold-down return spring. (The ABS braking system configuration is illustrated.)


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  9. Disconnect the upper link of the connecting link spring of the leading shoe to relieve tension on the upper return spring.
  10. Remove the upper return spring and the adjuster.


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  12. Unfasten the trailing shoe and lining assembly holddown return spring.


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  14. Disconnect the trailing shoe and lining assembly on the right side.
  15. Detach the lower return spring.


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Installation Procedure

  1. Measure the minimum brake lining thickness. Refer to "Lining Inspection" in this section.
  2. Clean the adjuster assembly and apply grease.
  3. Notice : If any parts are of questionable strength or quality because of heat discoloration, excessive stress, or wear, the shoes, the springs, or the adjuster assembly should be replaced.

  4. Inspect the threads of the adjuster assembly for smooth rotation.


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  6. Install the trailing shoe and lining assembly with the hold-down spring, the washer, and the pin.
  7. Make sure the parking brake cable is properly routed and attached to the shoe lever.
  8. Notice : Do not overstretch the lower return spring.

  9. Fasten the lower return spring on the shoe.


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  11. Position the leading shoe and the adjuster assembly against the backing plate.
  12. Fasten the lower return spring to the leading shoe.


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  14. Install the adjuster assembly.
  15. Turn the adjuster in as far as possible.
  16. Position the spring clip toward the backing plate.
  17. Install the leading shoe with the hold-down spring.


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  19. Attach the leading shoe upper link-spring connection, which applies tension to the upper return spring.
  20. Notice : Do not overstretch the upper return spring.

  21. Install the upper return spring from the spring connecting link to the brake shoe.


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    Notice : The nut must not lock firmly at the end of the adjustment assembly.

  23. Before installing the brake drum, make sure the adjuster assembly nut is drawn all the way to the stop.


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  25. Install the brake drum and fasten it with the rear hub caulking nut .
  26. Tighten
    Tighten the rear hub caulking nut to 190 N•m (140 lb-ft).

  27. Install the rear wheels. Refer to Section 2E, Tires and Wheels.
  28. Adjust the rear wheel brakes. Refer to "Brake Adjustment" in this section.
  29. Adjust the parking brake. Refer to Section 4G, Parking Brake.
  30. Lower the vehicle.


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Wheel Cylinder Assembly

Removal Procedure

  1. Raise and suitably support the vehicle.
  2. Remove the rear wheels. Refer to Section 2E, Tires and Wheels.
  3. Mark the position of the wheels relative to the wheel hubs.
  4. Remove the brake drum.
  5. Remove the shoe and lining. Refer to "Shoe and Lining" in this section.


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  7. Clean dirt and foreign material from around the wheel cylinder brake line inlet, the pilot, and the bolt.
  8. Disconnect the brake line from the wheel cylinder.
  9. Plug the opening in the brake line to prevent fluid loss or contamination.


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  11. Remove the wheel cylinder-to-backing plate bolt.
  12. Gently tap out the wheel cylinder from the backing plate, using care not to damage the bleeder valve or its cap.


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Installation Procedure

  1. Install the wheel cylinder to the backing plate with the wheel cylinder bolt.
  2. Tighten
    Tighten the wheel cylinder-to-backing plate bolt to 8 N•m (71 lb-in).



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  3. Connect the brake line to the wheel cylinder.
  4. Tighten
    Tighten the brake line to 16 N•m (12 lb-ft)

  5. Install the shoe and lining, and the brake drum. Refer to "Shoe and Lining" in this section.
  6. Bleed the brakes. Refer to Section 4A, Hydraulic Brakes.


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Backing Plate

Removal Procedure

  1. Raise and suitably support the vehicle.
  2. Remove the brake shoe components, including complete removal of the parking brake with the retainer. Refer to "Shoe and Lining" in this section and Section 4A, Hydraulic Brakes.
  3. Remove the nuts that secure the wheel hub assembly to the backing plate.
  4. Remove the brake line and plug the opening in the line to prevent fluid loss or contamination.


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  6. Remove the wheel cylinder assembly. Refer to "Wheel Cylinder Assembly" in this section.
  7. Remove the wheel hub assembly.
  8. In case of ABS brake, disconnect the cable that goes to the wheel speed sensor.
  9. Separate the backing plate and the gasket.

Installation Procedure

  1. Place the backing plate with a new gasket on the wheel hub. (The ABS hub is shown.).
  2. Insert the complete wheel hub/backing plate assembly into the rear axle plate. In case of ABS Brakes, Install the nuts and connect the wheel speed sensor.
  3. Tighten
    Tighten the brake wheel hub/backing plate-to-rear axle nuts to 28 N•m (21 lb-ft).



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  4. Install the brake wheel cylinder assembly to the backing plate. Refer to "Wheel Cylinder Assembly" in this section.
  5. Connect the brake line.
  6. Tighten
    Tighten the brake line to 16 N•m (12 lb-ft).

  7. Install the brake components. Refer to "Shoe and Lining" in this section.
  8. Install the parking brake cable with the retainer by attaching the cable to the brake shoe lever. Refer to Section 4G, Parking Brake.
  9. Bleed the brakes. Refer to Section 4A, Hydraulic Brakes.
  10. Lower the vehicle.

UNIT REPAIR



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Wheel Cylinder

Disassembly Procedure

  1. Remove the wheel cylinder assembly from the backing plate. Refer to "Wheel Cylinder Assembly" in this section.
  2. Twist off the boots, the pistons, and the seals from each end of the wheel cylinder.
  3. Remove the spring assembly.


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  5. Remove the bleeder cap and the bleeder valve.


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Assembly Procedure

  1. Inspect the wheel cylinder bore and the pistons for scoring, nicks, corrosion, and wear.
  2. Use a crocus cloth to polish out light corrosion in the wheel cylinder bore.
  3. Important : If the bore will not clean up with a crocus cloth, replace the assembly.



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  4. Clean all the parts in clean denatured alcohol or brake fluid. Dry all the parts with unlubricated compressed air and lubricate the new seals, the pistons, and the wheel cylinder bore with clean brake fluid before assembly.
  5. Thinly coat all the parts except the dust caps with brake cylinder fluid.
  6. Fasten the bleeder valve and the cap to the wheel cylinder.


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  8. Attach to the wheel cylinder the spring assembly, followed by the pistons, the seals, and the boots.
  9. Inspect the pistons for free movement.
  10. Install the wheel cylinder assembly. Refer to "Wheel Cylinder Assembly" in this section.

GENERAL DESCRIPTION AND SYSTEM OPERATION

Drum Brakes

This drum brake assembly is a leading/trailing shoe design. Both brake shoes are held against the wheel cylinder pistons by the lower return spring and the fixed anchor plate near the lower return spring. When the brakes are applied, the wheel cylinder pistons move both shoes out to contact the drum. With forward wheel rotation, the forward brake shoe will wrap into the drum and become self-energized. With reverse wheel rotation, the rear brake shoe is self-energized. Force from the brake shoes is transferred to the anchor plate through the backing plate to the axle flange. Adjustment is automatic and occurs on any service brake application. Do not switch the position of shoes that have been in service, as this may render the self-adjustment feature inoperative and result in increased pedal travel.

Notice : To avoid damaging the vehicle, observe the following directions:



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