Automobile & Light Truck Certification Test A5 BrakesDrum Brake Diagnosis and RepairMedium
A technician is inspecting a drum brake assembly. They notice that the automatic adjuster lever is bent and not properly engaging the star wheel. What is the MOST likely consequence of this issue?
- AA constant dragging of the brake shoes against the drum.
- BExcessive brake pedal travel and reduced braking efficiency.
- CPremature wear of the primary brake shoe.
- DContamination of the brake fluid by worn friction material.
Show answer & explanationAnswer & explanation
Correct answer: B. Excessive brake pedal travel and reduced braking efficiency.
If the automatic adjuster lever is bent and not engaging the star wheel, the brake shoes will not be properly adjusted as they wear. This leads to excessive clearance between the shoes and the drum, resulting in a low brake pedal and reduced braking effectiveness because the shoes have to travel further to contact the drum.
Why the other options are wrong
- A. A constant dragging would be caused by an OVER-adjusted or seized adjuster in the 'engaged' position, not one that isn't adjusting at all.
- C. Premature wear of the primary shoe is usually due to its self-energizing effect or contamination, not a faulty adjuster.
- D. Contamination of brake fluid is typically caused by internal component failure or improper maintenance, not a bent adjuster lever.
Faulty Automatic Adjuster
A malfunctioning automatic brake adjuster (e.g., bent lever) prevents the brake shoes from self-adjusting for wear, leading to excessive shoe-to-drum clearance and a low, spongy brake pedal.
- Increases pedal travel
- Reduces braking effectiveness
- Caused by lack of adjustment
Memory trick: No adjustment, no grab, just a long, soft stab.