Astro, Safari 1997-2005

Brake Shoes

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Adjustment




CAUTION
Dust and dirt accumulating on brake parts during normal use may contain asbestos fibers from production or aftermarket brake linings. Breathing excessive concentrations of asbestos fibers can cause serious bodily harm. Exercise care when servicing brake parts. Do not sand or grind brake lining unless equipment used is designed to contain the dust residue. Do not clean brake parts with compressed air or by dry brushing. Cleaning should be done by dampening the brake components with a fine mist of water, then wiping the brake components clean with a dampened cloth. Dispose of cloth and all residue containing asbestos fibers in an impermeable container with the appropriate label. Follow practices prescribed by the Occupational Safety and Health Administration (OSHA) and the Environmental Protection Agency (EPA) for the handling, processing, and disposing of dust or debris that may contain asbestos fibers.

Normal adjustments of the rear drum brakes are automatic and are made when the brakes are applied while the vehicle is driving in reverse. ONLY, if the linings have been replaced or if the self adjusters haven't worked properly, should the following procedure be performed.


NOTE
The following procedure requires the use of the GM Brake Adjustment tool No. J-4735 or equivalent.

  1. Raise and safely support the vehicle.
  2.  
  3. Using a punch and a hammer, at the rear of the backing plate, knock out the lanced metal area near the star wheel assembly.
    NOTE
    When knocking out the lanced metal area from the backing plate, the wheels must be removed and all of the metal pieces discarded.



    Click image to see an enlarged view

    Fig. The star wheel is used to adjust the rear brakes



    Click image to see an enlarged view

    Fig. Use a punch to pop out the adjuster knockouts if it hasn't already been done



    Click image to see an enlarged view

    Fig. Remove the metal tab from the backing plate. DO NOT allow it to fall into the drum

  4.  
  5. Using the GM Brake Adjustment tool No. J-4735 or equivalent, insert it into the slot and engage the lowest possible tooth on the star wheel. Move the end of the brake tool downward to move the star wheel upward and expand the adjusting screw. Repeat this operation until the brakes lock the wheel.

    Click image to see an enlarged view

    Fig. Use a brake adjusting spoon to turn the starwheel. A screwdriver just won't work that well

  6.  
  7. Insert a small screwdriver or piece of firm wire (coat hanger wire) into the adjusting slot and push the automatic adjuster lever out and free of the star wheel on the adjusting screw.
  8.  
  9. While holding the adjusting lever out of the way, engage the topmost tooth possible on the star wheel (with the brake tool). Move the end of the adjusting tool upward to move the adjusting screw star wheel downward and contact the adjusting screw. Back off the adjusting screw star wheel until the wheel spins freely with a minimum of drag. Keep track of the number of turns the star wheel is backed off.
  10.  
  11. Repeat this operation for the other side. When backing off the brakes on the other side, the adjusting lever must be backed off the same number of turns to prevent side-to-side brake pull.
    NOTE
    Backing off the star wheel 12 notches (clicks) is usually enough to eliminate brake drag.

  12.  
  13. Repeat this operation on the other side of the rear brake system.
  14.  
  15. After the brakes are adjusted, install a rubber hole cover into the backing plate slot. To complete the brake adjustment operation, make several stops while backing the vehicle to equalize the wheels.
  16.  
  17. Road test the vehicle.
  18.  

Removal & Installation




CAUTION
Dust and dirt accumulating on brake parts during normal use may contain asbestos fibers from production or aftermarket brake linings. Breathing excessive concentrations of asbestos fibers can cause serious bodily harm. Exercise care when servicing brake parts. Do not sand or grind brake lining unless equipment used is designed to contain the dust residue. Do not clean brake parts with compressed air or by dry brushing. Cleaning should be done by dampening the brake components with a fine mist of water, then wiping the brake components clean with a dampened cloth. Dispose of cloth and all residue containing asbestos fibers in an impermeable container with the appropriate label. Follow practices prescribed by the Occupational Safety and Health Administration (OSHA) and the Environmental Protection Agency (EPA) for the handling, processing, and disposing of dust or debris that may contain asbestos fibers.

  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Remove wheel and tire assembly.
  4.  
  5. Remove brake drum.
  6.  
  7. Remove return springs from the brake shoes.
  8.  
  9. Remove shoe guide.
  10.  
  11. Remove hold-down springs and pins.
  12.  
  13. Remove actuator lever and pivot.
  14.  
  15. Remove lever return spring.
  16.  
  17. Remove actuator link.
  18.  
  19. Remove parking brake strut and spring.
  20.  
  21. Remove parking brake lever.
  22.  
  23. Remove brake shoes and the adjuster assembly.
  24.  

To install:

  1. Lubricate the contact points on the backing plate and the adjuster with lithium grease.
  2.  
  3. Install parking brake lever, adjusting screw and spring assembly.
  4.  
  5. Install shoe assembly onto the backing plate.
  6.  
  7. Install parking brake lever, strut and strut spring.
  8.  
  9. Install actuator lever and lever pivot.
  10.  
  11. Install actuator link.
  12.  
  13. Install lever spring, the hold-down pins and springs.
  14.  
  15. Install shoe guide.
  16.  
  17. Install return springs and install the brake drum in position.
  18.  
  19. Adjust the brakes as follows:
    1. Remove the knockout area in the backing plate, behind the adjuster assembly.
    2.  
    3. Ensure the parking brake system is adjusted properly with no tension on the cables or parking brake lever. The tops of the shoes should be firmly seated against the upper spring retaining anchor, if not as specified, loosen the parking brake cables.
    4.  
    5. Install the drum and turn the brake adjuster until the wheels can just be turned by hand.
    6.  
    7. Then, back the adjuster off 24 notches. No brake drag should be felt after 12 notches.
    8.  
    9. Install an adjusting hole plug in the backing plate to prevent dirt and moisture from entering.
    10.  
    11. Readjust the parking brake cable as necessary.
    12.  

  20.  
  21. Install the wheel and tire assemblies.
  22.  
  23. Refill the master cylinder and pump pedal to attain full brake pedal before Road-testing the vehicle.

    Click image to see an enlarged view

    Fig. Exploded view of the drum brake components-Astro & Safari

  24.  

 
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