What Causes Abnormal Noise When Pressing the Brake Pedal in a Car?
3 Answers
Here are the specific reasons for abnormal noise when pressing the brake pedal in a car: 1. Improper installation of brake pads: When installing new brake pads, the old brake discs were not resurfaced, resulting in a poor fit. Poor installation or fitting new pads without resurfacing the old discs causes the new pads to rub directly against the uneven surface of the old discs, ultimately leading to uneven wear of the new brake pads. 2. Brake system malfunction: There may be inherent defects in the brake system, causing the brake pads to only partially contact the brake discs. This increases the pressure per unit area on the brakes, resulting in abnormal noise. It is recommended to inspect components such as the calipers and guide pins. 3. Presence of foreign objects: Foreign objects cause a mismatch in the contact surfaces, leading to abnormal noise.
Yesterday, my own car had the same issue—the screeching sound was so harsh it made my scalp tingle. Upon inspection, I found the brake pads had worn down to the limit, and the metal wear indicator was directly scraping against the brake rotor. In fact, unusual noises are like warning lights for the brake system. The three most common scenarios are: the brake pad wear indicator making noise, the brake rotor being scratched by hard debris, or the caliper not being properly installed and left loose. Once after driving in the rain, there was a creaking sound right after starting, and the mechanic said it was due to rust on the brake rotors, which disappeared after a few more brake applications. If the noise is accompanied by steering wheel vibration, it’s likely the brake rotor is warped and needs immediate attention—don’t wait until the wheel speed sensor gets damaged to regret it.
The most annoying brake noise I've encountered occurred right after installing new pads – a high-pitched screech like nails on a chalkboard. The mechanic explained this happens when the surface treatment layer on new pads hasn't worn off yet, and it should disappear after driving 200-300 km. But if it persists beyond a week, the brake discs might be getting grooved. That squeaking noise after a car wash? Turned out to be a small pebble stuck in the brakes – a few hard reverse stops dislodged it. The initial winter morning clicking sound is normal, just frozen brake pads. The real red flag is metallic grinding paired with spongy brakes – that could mean leaking brake fluid lines!
