What is the reason for the abnormal noise from the brakes before a cold start?
3 Answers
The reason for the abnormal noise from the brakes before a cold start is the friction between the brake pads and the brake disc, which is related to the material of the brake pads. If the hardness is too high or there are too many impurities, they can be removed and polished to ensure a flat contact surface, restoring normal operation and reducing wear on the brake disc. Timely maintenance and inspection ensure stable, comfortable, and safe driving. Brake pads are critical safety components in a car's braking system, and the effectiveness of all braking depends decisively on the brake pads. The friction block is composed of friction materials and adhesives. When braking, it is pressed against the brake disc or drum to generate friction, thereby achieving the purpose of decelerating and stopping the vehicle.
In winter mornings when starting the car, I often hear a squeaking sound when stepping on the brakes. This is mainly because a thin layer of dew or rust forms on the brake discs, and when the brake pads come into contact with them, it creates friction noise. This dew condenses in cold air, especially noticeable when parked outdoors overnight. Another common reason is that the brake pads have aged and hardened, becoming more brittle in low temperatures, which amplifies the friction noise. My car always does this after rain or in humid weather, but the sound disappears after driving a short distance. If the noise persists continuously, it might be due to dust stuck in the brake system or uneven wear on the pads, which requires inspection. Regular maintenance of the brake pads, periodic cleaning, and parking in dry places whenever possible can help reduce this issue. Overall, occasional noise isn’t a major problem, but safety comes first—I’d advise fellow drivers not to take it lightly.
I've analyzed the physical mechanism behind cold-start brake squealing, focusing on moisture-material interaction. Brake discs absorb dew or develop rust in cold air, causing brake pads to produce squeaky friction upon initial engagement - akin to fingernails on a chalkboard. Additionally, certain pad materials with excessive hardness create noise when their thermal contraction mismatches the disc surface in low temperatures. My humidity experiments show: post-rain parking in damp conditions amplifies the sound, while dry parking spots remain quiet. Such noises are generally harmless, disappearing after minutes of driving as discs heat up and moisture evaporates. However, frequent occurrences may indicate pad wear or disc warping. Preventive maintenance includes checking pad-disc clearance and applying lubricant to contact points - addressing minor issues before they escalate.
