What Causes the Metal Friction Sound When Getting on the Rear Wheel of a BMW 5 Series?
1 Answers
BMW 5 Series rear wheels producing a metal friction sound can be due to brake break-in, normal ABS system activation, metal hard spots on brake pads, severe brake disc wear, and other reasons. The details are as follows: Brake Break-in: New cars or recently replaced brake discs and pads have a break-in period, during which some noise is unavoidable. Therefore, they need to be worn in, which can cause noise, including vibration friction and sharp squealing sounds. This usually disappears after driving a few hundred kilometers. Normal ABS System Activation: During emergency braking, the brake pedal may produce a continuous thumping sound, sometimes accompanied by a pulsating sensation, indicating that the ABS system is activated. This is a normal sound. Metal Hard Spots on Brake Pads: Brake pads may contain small metal particles, which can produce sharp, piercing sounds when lightly braking. This issue can be resolved by forcefully applying the brakes several times, removing and regrinding the brake pads, or replacing them with higher-quality ones. Severe Brake Disc Wear: Brake disc wear can create deep grooves around the disc's edge, causing noise when the brake pads rub against these grooves. If the grooves are not too deep, grinding the edges of the brake pads to avoid contact with the grooves can solve the problem. If the grooves are very deep, it is recommended to replace the brake disc. Generally, it is advised to replace the brake disc after changing the brake pads twice.
