What Causes Brake Disc Vibration When Braking on Rainy Days?
3 Answers
Reasons for clicking sounds when braking in the rain: 1. Fine sand carried by rainwater adheres to the brake discs. In humid weather or when there is a large temperature difference between day and night, condensation or post-rain rust forms on the brake discs, equivalent to tiny particles. Car brake pads can be categorized as hard or soft. Hard pads are more wear-resistant, but if there are tiny particles between hard pads and gray cast iron brake discs, sharp noises may occur. A few brake applications will wear off these small particles. 2. The break-in period for new cars, where brake pad break-in is a crucial part. It usually takes several hundred kilometers of driving before the brakes feel more comfortable. Newly replaced brake pads also require a break-in period to better integrate with the old discs. Initially, the brakes may feel very stiff, and it typically takes several hundred kilometers of driving before they improve. 3. While driving, very small sand particles may get between the pads and discs, sometimes causing abnormal noises due to friction. This situation generally does not require repair; driving for a while will allow the small sand particles to fall out. 4. Missing or damaged brake disc mounting screws can also cause abnormal braking noises. 5. Brake system malfunction, which requires inspection and repair.
I think this situation is quite common in rainy weather. The reason may be that the surface of the brake disc gets wet from the rain, forming a thin water film or rust layer, which causes uneven friction between the brake pads and the disc, resulting in vibration. Sometimes, the vehicle's ABS (Anti-lock Braking System) may activate on slippery roads, creating a pulsating sensation that feels like shaking. The usual solution is to lightly apply the brakes a few times to heat up the disc and wear off the rust, or to find a safe place to stop and inspect the condition of the disc. If the shaking persists, it is recommended to visit a professional repair shop as soon as possible to have a technician check whether the brake system needs resurfacing or component replacement. Safety comes first when driving in the rain—don’t overlook these details to avoid bigger problems.
Driving in the rain is already troublesome, and sudden brake shuddering can be quite alarming. This is mostly due to rust on the brake discs or small puddles caused by rainwater, leading to unstable friction. The vibration could be the ABS system kicking in to control skidding, or it might be due to uneven disc surfaces. If you encounter this situation, don’t panic—keep the steering wheel steady, slow down gradually, and move to a safe spot away from busy areas. After stopping, use a flashlight to inspect the brake discs. If there’s noticeable rust, try lightly braking in neutral to wear it off; if that doesn’t help, contact a repair shop. Regular vehicle maintenance during rainy weather ensures good braking performance and reduces risks.
