Automobile & Light Truck Certification Test A5 BrakesDrum Brake Diagnosis and RepairMedium
A technician is replacing brake shoes on a drum brake system. What is the primary purpose of applying a thin layer of high-temperature grease to the shoe contact points on the backing plate?
- ATo lubricate the wheel cylinder pistons
- BTo reduce friction and prevent squealing/chattering
- CTo seal against moisture and corrosion
- DTo prevent brake dust accumulation
Show answer & explanationAnswer & explanation
Correct answer: B. To reduce friction and prevent squealing/chattering
Applying high-temperature grease to the brake shoe contact points (pads) on the backing plate reduces friction between the shoes and the backing plate. This allows the shoes to slide smoothly, preventing binding, reducing noise like squealing or chattering, and ensuring proper shoe movement during braking and release.
Why the other options are wrong
- A. Wheel cylinder pistons are lubricated by brake fluid, not external grease.
- C. While grease offers some corrosion protection, its primary role here is lubrication for movement and noise reduction.
- D. Grease does not prevent brake dust accumulation; it can actually attract it if applied excessively.
Brake Backing Plate Lubrication
Application of high-temperature, anti-seize lubricant to specific contact points on the drum brake backing plate.
- Ensures smooth shoe movement
- Prevents binding and sticking
- Reduces noise (squealing, chattering)
Memory trick: Smooth slide, no brake pride.