Why does the car sometimes make a 'thud' sound when braking?

[OLilliana]

Unusual sounds when braking could be due to normal ABS operation, safety reminders, loose chassis components, or unstable brake discs. The details are as follows: 1. ABS working process: It is actually a cyclic process of locking-releasing-locking-releasing, keeping the vehicle in a state of near-lock rolling. When you brake hard and trigger the ABS, it will produce a 'clunking' sound, which is normal. In this case, just press the brake pedal firmly to the end. 2. Safety reminder: If you hear a 'thud' sound between the transmission and the gear lever when pressing the brake pedal, the main reason for the sound may be the electronic linkage between the brake system and the automatic transmission. Pressing the brake activates the transmission solenoid valve, which produces a 'thud' sound. At this time, you need to press the gear lever lock button to shift gears, which serves as a kind of safety reminder.

[Tabitha]

I've experienced a 'clunk' sound when braking several times, especially on rainy days or after a cold start. This noise usually isn't a major issue, but it can be concerning. The most common causes are uneven brake pad wear or foreign objects stuck in the brake disc, such as small stones or rust. When braking sharply, the system may produce mechanical friction sounds. Additionally, in older vehicles, loose suspension components can cause clunking noises, like gaps caused by aging control arm bushings. I recommend first checking the brake discs and pads for obvious scratches or abnormal wear – use a flashlight for better inspection if possible. If the noise becomes louder or is accompanied by vibration, it might indicate ABS system activation or a brake hydraulic pump issue, which requires immediate professional inspection. Safety first – address problems early to avoid extended braking distances and potential accidents. Remember, regular maintenance is key to preventing such minor issues.

[DeAmir]

As an average car owner, I noticed occasional clunking sounds when braking within a year of purchasing my vehicle, especially during initial acceleration or low-speed braking. Initially, I was quite alarmed, but a friend later explained that this is quite common—it's usually caused by friction between the brake pads and discs. New brake pads sometimes require a break-in period, or damp weather can lead to rust buildup. However, if the noise occurs frequently, it's essential to inspect the braking system, as issues like loose wiring connections or insufficient brake fluid levels can also be the cause. My approach is straightforward: first, I monitor the frequency of the noise. If it happens daily, I promptly visit a 4S shop or a chain repair center for diagnostics. They can quickly identify the issue using equipment to measure braking force and check chassis integrity. Don't delay, as these sounds could indicate worn suspension ball joints or faulty brake calipers, which can be dangerous if left unaddressed. Regularly cleaning dust and debris from the wheel hubs during car washes can also help reduce noise. Make it a habit to perform simple monthly vehicle maintenance for safety.

[VanAdalynn]

A 'clunk' sound when braking is mainly caused by improper coordination of mechanical components. For example, brake pads that are too hard or excessively worn can produce a crisp collision sound; when the brake disc surface is uneven or scratched, unstable engagement between the pad and disc leads to abnormal noises. Additionally, gaps in the suspension system can amplify vibrations, such as when the shock absorber bushings age and the gaps increase, causing uneven force distribution and a clunking sound during braking. Mis-triggering of the ABS sensor can also produce a brief sound during hard braking. It is recommended to immediately check the thickness and wear pattern of the brake pads—using a thickness gauge can provide a preliminary assessment of whether replacement is needed. Also, ensure the brake fluid is clean, as contaminants can cause the pump piston to stick. If the issue persists, have a professional technician scan the vehicle's condition with a diagnostic computer to avoid further damage affecting braking performance.