See Figures 1 and 2
The rear drum brakes are equipped with automatic adjusters actuated by the brake mechanism. No periodic adjustment of the drum brakes is necessary if this mechanism is working properly. If the pedal travel is greater than normal, it may be due to a lack of adjustment at the rear. In a safe location, drive the car backwards at low speed. While backing, pump the brake pedal slowly several times (neither the speed of the car or the speed of pumping the pedal has any effect on the adjustment, the idea is to apply the brakes several times while backing). Drive forward and check the pedal feel by braking from moderate speed. It may take 2 or 3 passes in reverse to bring the pedal to the correct travel; each brake application moves the adjuster very little.
If brake shoe-to-drum clearance is incorrect and applying and releasing the brakes in reverse does not adjust it properly, the parts will have to be disassembled for repair.
An alternate method of adjustment can be used when the brakes have been disassembled or when the reversing method does not work.
- Elevate and safely support the vehicle. If only the rear wheels are elevated, block the front wheels with chocks. Once the vehicle is firmly on stands, release the parking brake.
- Remove the rear wheels.
- Remove the brake drum. It will not come off if the parking brake is applied.
If the brake drum cannot be removed easily:
- Insert a screwdriver through the hole in the backing plate and hold the adjusting lever away from the star wheel.
- Using a brake adjusting tool, turn the wheel to reduce the tension (increase the clearance) on the brake shoes.
- Use a brake drum measuring tool with both inside diameter and outside diameter capability. Measure the inside diameter of the brake drum and record the reading.
- Measure the diameter of the brake shoe assembly at the friction surface. Use the adjusting wheel to adjust the brake shoes until the diameter of the shoes is 0.024 in. (0.6mm) less than the diameter of the drum. This small clearance is important; over-adjusted brakes cause drag and premature wear on the shoes.
- Install the brake drum(s) and install the rear wheel(s).
- Apply the parking brake and lower the car to the ground.