GM Buick/Oldsmobile/Pontiac/Full-Size 1975-1990 Repair Guide

Adjustments

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DISC BRAKES



There is no adjustment provision on hydraulic disc brakes; they are inherently self-adjusting.

DRUM BRAKES



Drum brakes are self-adjusting, but provision is made for manual adjustment as follows:

  1. Raise the rear of the vehicle and support it with jackstands.
  2.  
  3. The inner sides of the brake backing plates have a lanced area, oblong in shape. Knock this area out with a punch. You will have to remove the brake drum to clean out any metal pieces that will be deposited by the punch, and you will have to purchase rubber plugs at a parts distributor to plug the punched holes now in the backing plats. Many vehicles will already have the holes punched and plugs installed.
  4.  
  5. Adjustment to tighten:
    1. Insert a brake adjusting spoon into the hole.
    2.  
    3. Turn the star-shaped adjusting screw inside the drum with the spoon, until the wheel has a slight drag. Do this to both wheels until there is equal drag on each wheel. DO NOT make the adjustment overtight!
    4.  

  6.  
  7. Adjustment to loosen and remove the drum:
    1. Insert a brake adjusting spoon and small prybar to hold the adjusting lever away from the sprocket.
    2.  
    3. Back off each adjusting screw until the drum turns freely. If the brake shoes drag with the adjusters backed off all the way, the parking brake cables could be excessively tight.
    4.  

  8.  

BRAKE PEDAL 1 / 4 in. on 1975 to 1984 models, 2 3 / 4 in. on 1985 to 1990 models and 3 1 / 3 in. on Hydro-boost systems.



The pedal travel is measured as the distance which the pedal moves towards the floor from the fully released position. Inspection should be made with the pedal firmly depressed and the brake system cold. Pedal travel should be 2

If equipped with power brakes, pump the 3 times with the engine OFF to remove vacuum reserve before checking pedal travel.

  1. Under the dash, remove the pushrod-to-pedal clevis pin.
  2.  
  3. Loosen the pushrod adjusting locknut and adjust the pushrod.
  4.  
  5. After the correct travel is established, tighten the locknut.
  6.  
  7. Engage the pushrod and secure using the clevis pin.
  8.  

 
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