Why does the car's brake squeak?

[DiNathan]

The causes and solutions for abnormal brake noises in cars are as follows: 1. Use of inferior or overly hard brake pads. Solution: Replace with high-quality brake pads. 2. Presence of foreign objects between the brake pads and brake discs. Solution: When driving at about 5 km/h, quickly press the brake several times; in most cases, this can remove the foreign objects. 3. Severe wear of the brake discs. Solution: Replace with new brake discs. 4. The brake pads have worn down to the warning line, triggering the brake pad alarm. Solution: It is recommended to send the car to a 4S shop as soon as possible for professional inspection and repair.

[DelSadie]

Actually, squeaky brakes are quite common, and it's mostly related to the brake pads. Last time I replaced the brake pads myself, I noticed that when the pads wear thin, the metal wear indicator on the back starts scraping against the brake rotor, producing a high-pitched sound like nails on a chalkboard. It's especially noticeable right after rain or washing the car because the brake rotor surface has moisture or rust, but the noise usually goes away after a few brake applications. If the noise consistently comes from the driver's side every time you brake, there might be a small stone or debris stuck between the pad and rotor. However, if the sound is dull and accompanied by steering wheel vibration, don't ignore it—it's likely a warped brake rotor. These issues require a proper inspection at a repair shop with the car lifted, paying special attention to whether the brake caliper guide pins are properly lubricated or stuck.

[ConnorLynn]

My car has been doing the same thing recently, with a particularly harsh squealing noise during cold starts. A knowledgeable friend took a look and said that semi-metallic brake pads are inherently harder, and the metal particles can scrape against the brake disc, causing noise in humid or cold weather. If the brake pads still have more than 3mm of thickness left, there's usually no rush to replace them, but remember to regularly clean out the accumulated metal shavings in the brake pad slots. I've also encountered noise caused by rust on the wheel hub before—removing the tire and sanding off the rust on the mating surface fixed it. However, for safety's sake, it's best to check the brake fluid's water content. If it exceeds the limit, it can affect the proper functioning of the brake caliper, and noise would be the least of your worries.

[Serena]

Ah, I know this issue all too well! The squeaking noise from new car brake discs is usually due to the anti-rust coating on the surface that hasn't been worn off yet—it'll disappear after driving about a hundred kilometers. If an older car suddenly starts making noise, there's an 80% chance it's the brake pad wear indicator reminding you it's time for a replacement. When you hear a creaking sound during slow braking before traffic lights, try stomping on the brakes hard a couple of times; sometimes this can shake out small embedded gravel. Rust noise from brake discs after washing the car is nothing to worry about, but if even light braking causes loud squealing, immediately check the brake caliper return spring. Last year, my neighbor's car ground deep grooves into the brake discs precisely because of this issue.

[EmilianoLynn]

Squeaky brakes in rainy weather are perfectly normal—it's just the sound of rust film being scraped off by the brake pads. However, if the noise persists in dry, sunny conditions, pay attention to three areas: whether the edges of the brake pads have developed sharp ridges, if the guide pin boots are aged or cracked, and whether the caliper bracket is deformed. A car we recently serviced at our repair shop had uneven wear due to lack of lubrication in the caliper sliders, causing the brake pads to squeal from angled friction. You can check the brake fluid reservoir level yourself—if it’s significantly below the minimum mark, the caliper might be leaking, preventing the piston from pushing fully. Also, for older cars with over 200,000 kilometers, remember to inspect the shoe springs in the rear drum brakes, as rusted or broken springs can cause unusual noises.