S&T Series Blazer, Bravada, Envoy, Jimmy, Rainier, Trailblazer, Xtreme

Brake Shoes

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Adjustments



Normal adjustments of the rear drum brakes are automatic and are made during the reverse applications of the brakes. The following procedure should be used ONLY if the linings have been replaced.

Click image to see an enlarged view

Fig. Drum brake adjustment

  1. Raise and support the rear of the vehicle safely using jackstands.
  2.  
  3. Using a punch and a hammer on the rear of the backing plates, knock out the lanced metal areas near the starwheel assemblies on each plate. The metal areas may already have been removed and covered with rubber adjustment plugs, if so remove the plugs by grasping and pulling with a pair of pliers.
    NOTE
    After knocking out the lanced metal areas from the backing plate, the wheels must be removed and all of the metal pieces discarded, then the wheels should be reinstalled for adjustment.

  4.  
  5. Insert a suitable brake adjustment tool such as J-4735 or equivalent, into the breaking plate slots and engage the lowest possible tooth on the starwheel. Move the end of the brake tool downward to move the starwheel upward and expand the adjusting screw. Repeat this operation until the wheels can JUST be turned by hand. This is a position immediately before the brakes lock.
    NOTE
    The brake drag should be equal at both wheels.

  6.  
  7. Back off the adjusting screws 24 notches (clicks). By the time you have backed off the adjustment 12 clicks, the brakes should have no drag. If a heavy drag is still present, the parking brake cable is likely in need of adjustment.
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  9. Make sure both sides of the brakes are properly adjusted. 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.
  10.  
  11. After the brakes are adjusted, install a rubber hole cover into each of the backing plate slots. To complete the brake adjustment operation, make several stops while backing the vehicle to fully equalize the adjustment.
  12.  
  13. Road test the vehicle.
  14.  

Removal & Installation



  1. Before servicing the vehicle, refer to the Precautions section.
  2.  
  3. Remove or disconnect the following:

    Wheel and tire assembly
     
    Brake drum
     
    Return springs from the brake shoes
     
    Remove the shoe guide
     
    Hold-down springs and pins
     
    Actuator lever and pivot
     
    Lever return spring
     
    Actuator link
     
    Parking brake strut and spring
     
    Parking brake lever
     
    Brake shoes and the adjuster assembly
     

  4.  

To install:

  1. Lubricate the contact points on the backing plate and the adjuster with lithium grease.
  2.  
  3. Install or connect the following:

    Parking brake lever, adjusting screw and spring assembly
     
    Shoe assembly onto the backing plate
     
    Parking brake lever, strut and strut spring
     
    Actuator lever and lever pivot
     
    Actuator link
     
    Lever spring, the hold-down pins and springs
     
    Shoe guide
     
    Return springs and install the brake drum in position
     

  4.  
  5. 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.  

  6.  
  7. Lower the vehicle, 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

  8.  

 
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