What Are the Reasons for Abnormal Noises When Braking Too Hard?

[VanKayden]

There are several reasons for abnormal noises when braking too hard, including the brake being in the break-in period, normal activation of the ABS system, metal hard spots on the brake pads, and severe wear of the brake disc. Brake in the break-in period: New cars or recently replaced brake discs and pads will have a break-in period, during which some abnormal noises are unavoidable. The noise will disappear after using the brakes a few times. Normal activation of the ABS system: During emergency braking, the brake pedal may produce continuous abnormal noises, sometimes accompanied by a kicking sensation, indicating that the ABS system is activated, which is a normal sound. Metal hard spots on the brake pads: There may be some tiny metal particles inside the brake pads, which can produce sharp, piercing sounds when lightly braking. Solutions include forcefully applying the brakes several times, removing and re-grinding the brake pads, or replacing them with higher-quality ones. Severe wear of the brake disc: Severe wear on the brake disc can form deep grooves around its circumference, causing friction between the brake pads and the edges of the grooves, resulting in abnormal noises. The solution is to promptly inspect the brake disc and replace it if the wear is severe.

[VonCatherine]

Last time I slammed on the brakes, I also heard that sharp sound. After checking, I found out it might be due to hard spots or uneven surfaces on the brake discs, causing noise when rubbing against the brake pads. Especially after rainy days when the brake discs rust, slamming on the brakes can easily cause squeaking. Another possibility is that the backing plate of the brake pads is loose or the shims are misaligned, leading to uneven force distribution. After long-term use, severe wear on the brake pads can expose the metal material inside, which can also produce unusual noises. It's recommended to regularly check the thickness of the brake pads and replace them if they are too thin. If the noise persists, it's best to have the brake system inspected at a repair shop, as it directly relates to driving safety.

[Eliza]

Having worked on cars for ten years, brake noise is a common issue I encounter. The most frequent cause is sand or small stones getting lodged in the brake pads, which then scrape against the brake disc when braking hard, creating noise. Another common issue is the caliper guide pins sticking or lacking sufficient lubrication, causing the brake pads to not retract promptly. There's also self-excited vibration from friction between the disc and pads, known professionally as brake disc judder. Additionally, aftermarket high-performance brake pads with high metal content offer strong braking power but tend to be noisy. My usual advice to car owners is to first clean the brake discs thoroughly and polish off any rust to see if that helps. If the noise persists, then inspect the calipers and consider replacing the brake pads with OEM ones.

[Diane]

From the perspective of automotive design, brake noise mostly occurs in disc brake systems. The mismatch between the friction material on the brake pad surface and the brake disc material can cause high-frequency vibrations, resulting in squealing. Many vehicle models now feature brake discs with noise-reducing shims, but these may become ineffective after aging. Additionally, when the ABS system is activated, it can cause vibrations in the brake pedal and produce specific noises, which are normal phenomena. When driving over potholes, the shock absorbers bear heavy loads, which may also cause impact noises from suspension components. Typically, brake noises in new cars will disappear after a few hundred kilometers of break-in. For older vehicles, it is recommended to replace the brake pads.