Why Is There Abnormal Noise from the Rear Drum Brakes?
2 Answers
Abnormal noise from the rear drum brakes is caused by either the brake shoe friction lining being worn out or uneven tension between the left and right brake shoes. Concept of Drum Brakes: Drum brakes utilize stationary brake shoes inside the brake drum to create friction against the rotating drum, thereby reducing the wheel's speed. When the brake pedal is pressed, the force applied by the foot pushes the piston in the master cylinder, which in turn pressurizes the brake fluid in the hydraulic lines. This pressure is transmitted to the wheel cylinders at each wheel, where the pistons push the brake shoes outward, causing them to rub against the inner surface of the brake drum. This friction generates sufficient resistance to slow down the wheel, achieving the braking effect. Causes and Solutions for Abnormal Noise: 1. Oil or grease contamination between the brake shoes and the drum can cause slipping and produce a sharp noise. Solution: Clean the brake drum and shoes with alcohol to remove the contamination. 2. If the surface of the brake shoes is too smooth, it can also lead to slipping and sharp noise. Solution: Use 800-grit sandpaper to roughen the surface of the brake shoes to increase friction.
The squeaking noise from rear drum brakes is quite annoying, mainly caused by excessive wear or hardening of the brake shoes, leading to uneven friction and sound. The sealed structure of drum brakes easily accumulates dust or small foreign objects like sand, causing rattling when trapped inside. I've also encountered issues with loose or rusted adjustment springs, which destabilize brake components. Aging wheel bearings can transmit noise to the brakes, especially in older cars or poor road conditions. Insufficient lubrication or moisture-induced rust is common during rainy seasons. These issues must be addressed promptly; otherwise, braking performance declines, making driving unsafe. Professional inspection, cleaning, or part replacement at a shop often resolves the problem. Daily driving habits like avoiding frequent hard braking and maintaining shock absorbers can extend their lifespan.
