Brake Shoe: Adjustments

These brakes have self-adjusting shoe mechanisms that assure correct lining-to-drum clearances at all times. The automatic adjusters operate only when the brakes are applied when the car is moving rearward.Although the brakes are self-adjusting, an initial adjustment is necessary when the brake shoes have been relined or replaced, or when the length of the star wheel adjuster has been changed during some other service operation.Frequent usage of an automatic transmission forward range to halt reverse vehicle motion may prevent the automatic adjusters from functioning, thereby inducing low pedal heights. Should low pedal heights be encountered, it is recommended that numerous forward and reverse stops be made until satisfactory pedal height is obtained.If a low pedal height condition cannot be corrected by making numerous reverse stops (provided the hydraulic system is free of air) it indicates that the automatic adjusting mechanism is not functioning. Therefore, it will be necessary to remove the brake drum, clean, free up and lubricate the adjusting mechanism. Then adjust the brakes, being sure the parking brake is fully released.

ADJUSTMENT
When servicing a vehicle requiring a brake adjustment, the metal knock-out plugs should NOT be removed. Rather the drums should be removed and brakes inspected for a malfunction.Although the brakes are self-adjusting, an initial adjustment will be necessary after a brake repair, such as relining or replacement. The initial adjustment can be obtained by the procedure outlined below.If after removing brake drum retainers, the brake drum cannot be removed, remove steel knock-out plugs (if equipped) with suitable hammer and chisel. If equipped with rubber plugs, pry plug from backing plate. Insert a narrow screwdriver through hole in backing plate and disengage lever from adjusting screw. While holding lever away from adjusting screw, back off adjusting screw using a suitable tool to retract brake shoes.

Fig. 5 Brake adjustment with gauge:

1. Use the brake shoe adjustment gauge shown in Fig. 5 to obtain the drum inside diameter as shown. Tighten the adjusting knob on the gauge to hold this setting.
2. Place the opposite side of the gauge over the brake shoes and adjust the shoes by turning the adjuster screw until the gauge just slides over the linings. Rotate the gauge around the lining surface to assure proper lining diameter adjustment and clearance.
3. Install brake drum and wheel. Final adjustment is accomplished by making several firm reverse stops, using the brake pedal.