What Causes the Squeaking Sound When Braking at Low Speeds?
4 Answers
Car braking at low speeds causes squeaking sound due to: 1. Missing or damaged brake disc fixing screws; 2. Insufficient lubrication in the braking system; 3. Small particles between brake pads and discs; 4. Dirty brake disc surface or uneven material density causing severe wear. Braking, also known as deceleration, refers to the action of stopping or reducing the speed of moving locomotives, vehicles, and other transportation tools or machinery. Its working principle is: fixing a wheel or disc on the machine's high-speed shaft, installing corresponding brake shoes, bands, or discs on the machine base, which generate braking torque under external force.
I've encountered the issue of squeaking brakes during low-speed driving several times, and the most common cause is worn-out brake pads. There's a small metal indicator embedded in the brake pad that scrapes against the rotor when the pad reaches its wear limit, producing a warning sound. If it's just rained or the car hasn't been driven for a while, surface rust on the rotors can also cause this friction noise during low-speed braking. Newly replaced brake pads require a break-in period, and the noise typically disappears after a few hundred kilometers of driving. I've also noticed that some hard-compound brake pads are inherently prone to noise, but this doesn't affect braking performance. Occasionally, small stones trapped between the brake pad and rotor can cause squeaking, but the noise stops once the debris falls out. Regular inspection of brake pad thickness is crucial - they should be replaced when worn down to less than 3mm. If the noise becomes progressively louder or develops into a harsh metallic screeching sound, it's wise to visit a repair shop immediately for inspection.
That squeaky noise when braking at low speeds is really annoying. I recently encountered this issue, and there are mainly three possibilities: The simplest one is sand or small metal shavings stuck on the brake disc surface—cleaning it usually solves the problem. Another common cause is when the brake pads wear down over time, forming hard edges that screech like nails on a chalkboard, especially with metal brake pads. If it happens on cold winter mornings, frost on the brake pads can also cause a brief squeal, which disappears after driving for a few minutes. The most dangerous scenario is when the brake pad wear indicator (a thin metal tab) contacts the brake disc, producing a whistling sound. I recommend checking the groove depth of the brake pads—if the central groove is nearly worn flat, it's time to replace them. Never delay fixing this issue; losing braking power mid-drive would be disastrous.
Low-speed brake squealing is mostly caused by friction issues. I've cleaned the brake discs myself and found that accumulated grease and metal shavings in the gaps are the most common culprits for squeaking sounds. Additionally, rainy days or high-humidity environments can trigger chemical reactions in brake pads, causing sudden changes in friction coefficients and generating noise. Ventilated brake discs with grooves tend to fling dust inside, leading to jamming. Recently, I've noticed that lack of lubrication on guide pins can also cause brake pad misalignment and squealing. The solution isn't difficult—first check the brake disc surface for obvious scratches or grooves, then use specialized cleaner to wash the braking system. It's best to replenish high-temperature grease on brake caliper pins during annual maintenance. Remember, never attempt to disassemble brakes yourself—safety components require professional handling.
