What Causes Abnormal Noise When Braking in Reverse?
1 Answers
The main reasons for abnormal noise when a car is reversing are as follows: 1. Break-in period causes directional wear on brake pads. Since the brake disc itself develops scratches, the contact area with new brake pads is initially small, resulting in weak braking force at first. However, prolonged contact and friction cause the surface imprints to align, ensuring sufficient braking force during braking. Yet, this break-in process also creates directional characteristics in the friction layer of the brake pads. 2. Vibration and squealing due to disrupted torque balance. Due to the principles of physical torque, the friction pressure at the front and rear ends of the brake pads differs. The front-end pressure is generally significantly lower than the rear-end pressure. Therefore, in some "multi-piston" caliper products, the pistons closer to the front end of friction are often smaller, leading to abrupt braking engagement during reverse braking and accompanying squealing noises caused by torque imbalance. 3. Accumulation and re-entrainment of wear debris into the friction surface. During operation, brake pads inevitably produce some wear debris, which consists of particles shedding from the surface of the brake pads. These debris accumulate on one side of the brake pad as the brake disc rotates. Reversing suddenly changes the friction direction, causing the debris to be re-entrained between the brake disc and brake pads.
