What causes the squealing sound when stepping on the brake?
4 Answers
There are five main reasons for the squealing sound when braking: 1. Severely worn brake discs: When brake pads rub against uneven brake discs, abnormal noises may occur. 2. Foreign objects in brake discs: When driving on complex road conditions, wheels can easily fling stones or other debris. 3. Poor quality brake pads: If non-standard manufacturer brake pads are installed or low-quality brake pads are used, the overly hard material will cause abnormal noises during braking and may damage the brake discs. 4. Severely worn brake pads: After prolonged use, brake pads become thinner due to constant friction. Overly thin brake pads not only reduce braking effectiveness but also harden, causing abnormal noises. 5. Rusty brake discs: Long-term exposure to weather can cause brake discs to rust.
My old car had this issue too – that annoying squealing sound when braking. The most common cause is worn-out brake pads. There's a small metal tab designed to alert you when it's time for replacement; when the pads wear down to it, you'll hear that metal scraping noise. Another possibility is sand or small stones stuck in the brake pads, which might shake loose after driving a few kilometers. If it's just rained or you've recently washed the car, temporary rust on the brake rotors can also cause noise, but it usually goes away after a few brake applications. Of course, if the sound is particularly sharp or accompanied by steering wheel vibration, it could indicate warped brake rotors, and you should get it checked at a repair shop immediately. Never ignore brake issues – safety should never be compromised.
A squealing sound when braking is mostly related to the brake pads. I've personally encountered two typical situations: one was a rustling noise during hard braking, which the mechanic explained was due to new brake pads still in the break-in period with unevenly distributed metal particles; the other was a high-pitched metal-on-metal screech even with light braking, and upon inspection, it turned out the anti-noise shim on the back of the brake pad had come off. Another potential issue is hard spots on the edge of the brake rotor, which can cause periodic noise when they contact the problematic area. If the noise persists after replacing the brake pads, check whether the noise-reduction paste was properly applied during installation. It's advisable to get the car lifted and inspected at a shop as soon as possible—after all, brake issues are no small matter.
Listen to the sounds for the most direct clues: A high-pitched screech like metal scraping against a wok means your brake pads are 90% worn out. If there's a creaking noise during low-speed turns, it's likely the guide pins need lubrication. That's exactly what happened to my car last week—I bought some anti-squeal spray and applied it to the back of the brake pads, which solved the issue. A light squealing after rain is normal and usually disappears within two kilometers of driving. But beware! If metallic noises come with noticeably longer stopping distances, your brake discs might have grooves and require resurfacing with a lathe. Avoiding sudden stops can significantly extend your brake pads' lifespan.
