Why doesn't the rear disc brake of the motorcycle work properly?
3 Answers
The rear disc brake may not work properly due to excessive wear of the brake pads, aging or damage of the brake pump, issues like sticking or insufficient pressure causing oil leakage, or the brake oil level being too low. Additionally, check if the passages in the pump are blocked. It might be necessary to replace the brake pump. Here is some additional information: 1. Disc brake: A disc brake consists of a brake disc connected to the wheel and a brake caliper at the edge of the disc. When braking, high-pressure brake oil pushes the brake pads to clamp the disc, creating the braking effect. 2. Function of disc brakes: Disc brakes have flat brake shoes on both sides of the brake disc. When the hydraulic pressure from the master cylinder is delivered to the wheel cylinder, it causes the brake shoes to clamp the disc, achieving the braking effect.
I often ride motorcycles. Last month, the rear brake completely failed, and I almost had an accident. I immediately checked the cause and found that the brake pads were worn extremely thin, rendering the friction ineffective. The mechanic said there might be air bubbles in the brake lines, causing insufficient pressure, or the brake fluid might have deteriorated and turned black, affecting performance. The caliper also had major issues—the pistons were corroded and not retracting properly, leading to excessive gaps and ineffective braking. Oil contamination or scratches on the disc during riding can make things worse, further weakening braking. It's recommended to measure the pad thickness during every maintenance session and replace them if they're less than 2mm. Brake fluid should be replaced every two years to keep it clear. Safety comes first—if there's a malfunction, don't ride; stop immediately and test the brakes. Regularly clean the disc to prevent dust buildup, and be extra cautious in rainy or slippery conditions, as brakes are more prone to failure then.
Common reasons for ineffective rear disc brakes: The most common is excessive wear of brake pads, leading to loss of friction; aging or water-contaminated brake fluid, or air in the brake lines reducing compressibility; caliper issues like stuck pistons or weak return force; fluid leaks causing insufficient hydraulic pressure; worn or greasy disc rotors. Inspection steps include checking pad thickness, fluid level, and listening for abnormal noises. A simple DIY fix is to try bleeding the brakes to see if performance improves. For daily riding, adopt gentle and gradual braking habits, avoiding sudden stops to prolong component life. Regularly replace brake fluid to prevent sedimentation, and lubricate calipers to prevent rust. Ineffective braking severely impacts control, especially during high-speed cornering where danger increases significantly, necessitating prompt repairs.
