Problem: Improper rear drum brake adjustment.
Cause: Not understanding when and how self-adjustment takes place on duo-servo and non-servo drum brake equipped vehicles.
Solution: Learning to identify the self-adjusting parts and when they operate will allow the following:
- Determining whether the self-adjusting mechanism is operating as designed.
- Allow proper assembly or repair of self-adjustment mechanism
- Identify when self-adjustment takes place
Duo-Servo Drum Brakes
All duo-servo drum brakes are designed to self-adjust when backing up only if the following conditions are met:
- If there is a large enough gap between the secondary brake shoe and brake drum.
- if the parts that make up the self-adjusting mechanism are operating properly.
When servicing vehicles with duo-servo drum brakes it is important to make sure all parts are lubricated and installed correctly.
Non-Servo Drum Brakes
Figure 60.1 Figure 60.2