Why is there a noise when releasing the brake?
2 Answers
This is a normal phenomenon for automatic transmission vehicles. The brake noise is caused by the gap between the brake pads and the uneven hardness of the brake discs, which contain materials like copper or other metals, leading to an uneven surface on the brake pads. The details are as follows: 1. The lighter and slower, the more noticeable: The slower and lighter you release the brake, the more noticeable this noise becomes. This is because in an automatic transmission vehicle, as long as the gear lever is not in Park (P) or Neutral (N), the engine continues to output power, even at idle. To stop the vehicle, you must press the brake pedal. 2. Braking force versus power: When starting, the engine's power is already applied to the wheels, but the wheels do not move because the braking force is greater than the power. When the braking force is less than the power, the wheels start to move. As you release the brake pedal, when the power and braking force reach a critical point, the friction between the brake pads and discs produces noise. If you quickly release the brake pedal (when conditions permit), there is no noise.
Brake lift noise can be caused by several common issues, which I've encountered over years of driving. The most frequent cause is worn brake pads or small stones stuck in them, producing a squeaking sound. Alternatively, rust or water on the brake disc surface can create friction noise. Loose caliper components may also cause creaking, especially in humid weather. Another possible reason is related to the suspension system, such as worn steering knuckles, which can produce abnormal vibration sounds when lifting the foot. If the noise only occurs under specific conditions, like during cold starts, it's likely temporary and can be alleviated by pressing the brakes a few more times. However, if the noise persists or worsens, it's advisable not to ignore it and to promptly visit a reliable repair shop to check brake pad thickness and overall system safety. Regular maintenance, such as biannual brake inspections, can significantly reduce such issues and ensure smooth driving. I usually practice gentle brake lifting to extend component lifespan, which works well. In summary, while brake noise may seem minor, timely attention ensures peace of mind.
