What Causes Brake Noise When the Car is Cold?
3 Answers
Cold-start brake noise occurs due to the following reasons: 1. In principle, braking involves friction between two components that converts mechanical energy into thermal energy. During this process, intense friction generates severe vibrations. When the vibration frequency matches or approaches the natural frequency of the brake pads (or related components), resonance occurs, leading to abnormal noises or squealing. This is particularly noticeable when descending garage ramps. 2. Braking systems are typically divided into disc brakes and drum brakes, with disc brakes being more prone to these abnormal noises/squeals. 3. Drum brakes: Due to their larger size and heavier weight, their natural frequency is lower. Low-frequency resonance from outside the vehicle often fails to transmit sound into the cabin, making occurrences rare. 4. Disc brakes: Their smaller size, lighter weight, and higher natural frequency make them susceptible to high-frequency resonance, resulting in abnormal noises/squeals. Resonance can occur across various components—brake discs, brake pads, calipers, etc. The piercing squeals heard are usually emitted by the resonance of the brake discs.
I've been driving for almost twenty years, and often in winter or humid mornings, the brakes squeak, mainly because the brake discs get dew or moisture after parking overnight, causing surface rust. The first brake in the morning grinds off the rust powder, making noise. This isn't a serious issue and usually disappears after driving for a few minutes once the car warms up. However, if the sound is sharp and persistent, it might indicate that the brake pads are worn to the limit, with metal pieces rubbing against the disc, or small stones and dust have accumulated. It's recommended to lightly pump the brakes a few times to warm them up before driving in cold weather. Also, rinse the brake components inside the wheel hubs during car washes to reduce dirt buildup. If the problem is severe, have the brake system checked at a shop to ensure safety. Regular maintenance is crucial, especially for older vehicles, which require extra attention.
As someone who frequently drives long distances, I pay special attention to safety details. Cold brake squealing is mostly caused by component contraction due to low morning temperatures, increasing friction, or rust and impurities between the discs. Long-term neglect may accelerate wear and affect braking power, making it more dangerous on slippery rainy roads. When performing DIY inspections, check if the brake pads are too thin—replace them if the warning light comes on or if the thickness is less than 3mm by hand measurement. Keeping the wheels clean to avoid dust accumulation is very effective. During daily driving, observe abnormal noise patterns and assess severity based on braking feedback. Address any issues as early as possible—don't wait until they become major problems leading to accidents. Drive smoothly in cold weather, avoid sudden braking, and warm up the car before hitting the road.
