See Figure 1
The drum brakes are self-adjusting and require a manual adjustment only after the brake shoes have been replaced, or when the length of the adjusting screw has been changed while performing some other service operation, as i.e., taking off brake drums.
To adjust the brakes, follow the procedures given below:Drum Installed
See Figures 2, 3 and 4
- Raise and support the rear end on jackstands.
- Remove the rubber plug from the adjusting slot on the backing plate.
- Insert a brake adjusting spoon into the slot and engage the lowest possible tooth on the starwheel. Move the end of the brake spoon downward to move the starwheel upward and expand the adjusting screw. Repeat this operation until the brakes lock the wheels.
- Insert a small prytool or piece of firm wire (coat hanger wire) into the adjusting slot and push the automatic adjusting lever out and free of the starwheel on the adjusting screw and hold it there.
- Engage the top-most tooth possible on the starwheel with the brake adjusting spoon. Move the end of the adjusting spoon upward to move the adjusting screw starwheel downward and contract the adjusting screw. Back off the adjusting screw starwheel until the wheel spins freely with a minimum of drag. Keep track of the number of turns that the starwheel is backed off, or the number of strokes taken with the brake adjusting spoon.
- Repeat this operation for the other side. When backing off the brakes on the other side, the starwheel adjuster must be backed off the same number of turns to prevent side-to-side brake pull.
- Remove the safety stands and lower the vehicle. Road test the vehicle.
- When the brakes are adjusted make several stops while backing the vehicle, to equalize the brakes at both of the wheels.
- Make sure that the shoe-to-contact pad areas are clean and properly lubricated.
- Using an inside caliper check the inside diameter of the drum. Measure across the diameter of the assembled brake shoes, at their widest point.
- Turn the adjusting screw so that the diameter of the shoes is 0.030 in. (0.76mm) less than the brake drum inner diameter.
- Install the drum.