GM Full Size Vans 1967-1986 Repair Guide

Brake Shoes

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INSPECTION



Remove the drum and inspect the lining thickness on both brake shoes. A front brake lining should be replaced if it is less than 1 / 8 in. (3mm) thick at the lowest point on the brake shoe. The wear limit for rear brake linings is 1 / 16 in. (1.5875mm).

Brake shoes should always be replaced in axle sets. The wear specifications given may disagree with your state inspection rules.

REMOVAL & INSTALLATION

See Figures 1 through 10



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Fig. Fig. 1: Use an evaporative spray brake cleaner to remove brake dust from the components



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Fig. Fig. 2: Use a brake tool to release the return springs



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Fig. Fig. 3: Remove the second return spring ... .



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Fig. Fig. 4: ... then remove the actuator link



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Fig. Fig. 5: Remove the shoe guide from the stud at the top of the backing plate



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Fig. Fig. 6: Use the brake tool to compress the hold-down spring and twist the plate to free the pin



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Fig. Fig. 7: Once the pin and the slot on top of the plate are aligned, separate the hold-down spring and pin



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Fig. Fig. 8: You can remove the adjuster spring at this time



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Fig. Fig. 9: Remove the bottom return spring



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Fig. Fig. 10: Remove the parking brake strut and spring


CAUTION
Brake shoes may contain asbestos, which has been determined to be a cancer causing agent. Never clean the brake surfaces with compressed air! Avoid inhaling any dust from any brake surface! When cleaning brake surfaces, use a commercially available brake cleaning fluid.

  1. Jack up and securely support the vehicle.
  2.  
  3. Loosen the parking brake equalizer enough to remove all tension on the brake cable (rear brakes only).
  4.  
  5. Remove the brake drums.
  6.  


WARNING
The brake pedal must not be depressed while the drums are removed.

  1. Using a brake tool, remove the shoe springs. You can do this with ordinary tools, buy it isn't easy.
  2.  
  3. Remove the self-adjuster actuator spring.
  4.  
  5. Remove the link from the secondary shoe by pulling it from the anchor pin.
  6.  
  7. Remove the hold-down pins. These are the brackets which run though the backing plate. They can be removed with a pair of pliers. Reach around the rear of the backing plate and hold the back of the pin. Turn the top of the pin retainer 45° with the plier. This will align the elongated tang with the slot in the retainer. Be careful, as the pin is spring loaded and may fly off when released. Use the same procedure for the other pin assembly.
  8.  
  9. Remove the adjuster actuator assembly.
  10.  

Since the actuator, pivot, and override spring are considered an assembly it is not recommended that they be disassembled.

  1. Remove the shoes from the backing plate. Make sure that you have a secure grip on the assembly as the bottom spring will still exert pressure on the shoes. Slowly let the tops of the shoes come together and the tension will decrease and the adjuster and spring may be removed.
  2.  

If the linings are to be reused, mark them for identification.

  1. Remove the rear parking brake lever from the secondary shoe. Using a pair of plier, pull back on the spring which surrounds the cable. At the same time, remove the cable from the notch in the shoe bracket. Make sure that the spring does not snap back or injury may result.
  2.  
  3. Use a cloth to remove dirt from the brake drum. Check the drums for scoring and cracks. Have the drums checked for out-of-round and service the drums as necessary.
  4.  
  5. Check the wheel cylinders by carefully pulling the lower edges of the wheel cylinder boots away from the cylinders. If there is excessive leakage, the inside of the cylinder will be moist with fluid. If there is any leakage at all, a cylinder overhaul is in order. DO NOT delay, as a brake failure could result.
  6.  

A small amount of fluid will be present to act as a lubricant for the wheel cylinder pistons.

  1. Check the flange plate, which is located around the axle, for leakage of differential lubricant. This condition cannot be overlooked as the lubricant will be absorbed into the brake linings and brake failure will result. Replace the seals as necessary. See Drive Train for details.
  2.  

If new linings are being installed, check them against the old units for length and type.

  1. Check the new linings for imperfections.
  2.  


CAUTION
It is important to keep your hands free of dirt and grease when handling the brake shoes. Foreign matter will be absorbed into the linings and result in unpredictable braking.

  1. Lightly lubricate the parking brake and cable and the end of the parking brake lever where it enters the shoe. Use high temperature, waterproof, grease or special brake lube.
  2.  
  3. Install the parking brake lever into the secondary shoe with the attaching bolt, spring washer, lockwasher, and nut. It is important that the lever move freely before the shoe is attached. Move the assembly and check for proper action.
  4.  
  5. Lubricate the adjusting screw and make sure that it works freely. Sometimes the adjusting screw will not move due to lack of lubricant or dirt contamination and the brakes will not adjust. In this case, the adjuster should be disassembled, thoroughly cleaned, and lubricated before installation.
  6.  
  7. Connect the brake shoe spring to the bottom portion of both shoes. Make certain that the brake linings are installed in the correct manner, the primary and secondary shoe in the correct position. If you are not sure remove the other brake drum and check it.
  8.  
  9. Install the adjusting mechanism below the spring and separate the top of the shoes.
  10.  
  11. Make the following checks before installation:
    1. Be certain that the right hand thread adjusting screw is on the left hand side of the vehicle and the left hand screw is on the right hand side of the vehicle.
    2.  
    3. Make sure that the star adjuster is aligned with the adjusting hole.
    4.  
    5. The adjuster should be installed with the starwheel nearest the secondary shoe and the tension spring away from the adjusting mechanism;
    6.  
    7. If the original linings are being reused, put them back in their original locations.
    8.  

  12.  
  13. Install the parking brake cable.
  14.  
  15. Position the primary shoe (the shoe with the short lining) first. Secure it with the hold-down pin and with its spring by pushing the pin through the back of the backing plate and, while holding it with one hand, install the spring and the retainer using a pair of needlenose pliers. Install the adjuster actuator assembly.
  16.  
  17. Install the parking brake strut and the strut spring by pulling back the spring with pliers and engaging the end of the cable onto the brake strut and then releasing the spring.
  18.  
  19. Place the small metal guide plate over the anchor pin and position the self-adjuster wire cable eye.
  20.  


WARNING
The wire should not be positioned with the conventional brake installation tool or damage will result. It should be positioned on the actuator assembly first and then placed over the anchor pin stud by hand with the adjuster assembly in full downward position.

  1. Install the actuator return spring. DO NOT pry the actuator lever to install the return spring. Position it using the end of a screwdriver or another suitable tool.
  2.  

If the return springs are bent or in any way distorted, they should be replaced.

  1. Using the brake installation tool, place the brake return springs in position. Install the primary spring first over the anchor pin and then place the spring from the secondary show over the wire link end.
  2.  
  3. Pull the brake shoes away from the backing plate and apply a thin coat of high temperature, waterproof, grease or special brake lube in the brake shoe contact points.
  4.  


WARNING
Only a small amount is necessary. Keep the lubricant away from the brake linings.

  1. Once the complete assembly has been installed, check the operation of the self-adjusting mechanism by moving the actuating lever by hand.
  2.  
  3. Adjust the brakes.
    1. Turn the star adjuster until the drum slides over the brakes shoes with only a slight drag. Remove the drum:
    2.  
    3. Turn the adjuster back 1 1 / 4 turns.
    4.  
    5. Install the drum and wheel and lower the vehicle.
    6.  

  4.  


CAUTION
Avoid overtightening the lug nuts to prevent damage to the brake disc or drum. Alloy wheels can also be cracked by overtightening. Use of a torque wrench is highly recommended.

If the adjusting hole in the drum has been punched out, make certain that the insert has been removed from the inside of the drum. Install a rubber hole cover to keep dirt out of the brake assembly. Also, be sure that the drums are installed in the same position as they were when removed, with the locating tang in line with the locating hole in the axle shaft flange.

    1. Make the final adjustment by backing the vehicle and pumping the brakes until the self-adjusting mechanisms adjust to the proper level and the brake pedal reaches satisfactory height.
    2.  


  1. Adjust the parking brake. Details are given later.
  2.  

 
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