Why does the automatic transmission make noise when releasing the foot brake at startup?

[Frieda]

There are several reasons for the abnormal noise when releasing the brake during automatic transmission startup: 1. Slow brake release: This noise is mainly caused by releasing the brake too slowly during startup, which is a common issue for many automatic transmission car owners. When the brake pedal is released gradually, the engine already has sufficient power to drive the car forward, but the brake is not fully released. As a result, the moving wheels are restrained by the brake system, naturally causing abnormal noise. So next time, remember to release the brake faster. 2. Brake disc and brake pad sticking together due to rust: This usually happens after driving in rainy weather and then leaving the car unused for several days. The brake disc and brake pad rust and stick together, causing abnormal noise when starting the car again. This can be resolved by applying butter or special lubricating oil to the connection between the brake pad and brake caliper at a repair shop. 3. Metal noise: Many brake pads nowadays are made of semi-metallic materials, containing a large number of metal fibers. Sometimes, metal particles form, producing a harsh sound when stepping on or releasing the brake. This condition usually disappears after driving for a while. If it persists, it may be due to poor manufacturing quality, and it is recommended to replace the brake pads promptly to avoid scratching the brake disc.

[AnthonyFitz]

My car makes a clicking sound when I release the brake. I asked a mechanic, and they said it's mostly the sound of the brake pads separating from the brake discs. Automatic transmission cars also make this noise when the electronic handbrake automatically releases during hill starts. If the sound is particularly harsh, it might be worth checking the wear level of the brake pads, as the metal wear indicators rubbing against the discs can produce sharp noises. It's best to avoid parking in damp places for extended periods, as this can cause the brake discs to rust and stick.

[LolaAnn]

This clicking sound is quite common, basically the normal pressure relief noise from the brake hydraulic system during gear shifting. In automatic transmission vehicles, when shifting to D gear and releasing the foot brake, the transmission gears engage and produce mechanical sounds. My car had the same issue when newly purchased, and I later noticed it's more pronounced when parked on slopes. The 4S dealership explained it's caused by the designed clearance between brake pads, resulting in normal vibration sounds. As long as there's no accompanying brake pedal vibration or reduced braking force, it's not a problem.

[AlanLynn]

The issue of noise when releasing the brake is mainly related to the parking brake mechanism. When the P-gear lock of an automatic transmission is released, there's a clicking sound. Some models with electronic parking brakes also automatically activate hill-start assist, making the brake pump's operation noise quite noticeable upon release. My car often does this during cold starts, and the mechanic said it's normal. However, if the noise is exceptionally loud every day, it's advisable to check the brake guide pins, as lack of lubrication can indeed increase friction noise.

[April]

I noticed this phenomenon right after getting my driver's license and specifically researched it. It's actually the sound of the brake caliper piston returning to position, particularly more noticeable in models with electronic parking brakes. Different car brands produce different sounds - German cars often have a slight clicking noise, while Japanese cars mostly make a whooshing air sound. Once after parking for two rainy days, it made loud noises when starting, and the mechanic said it was due to rust causing brake pad adhesion. Just remember to check brake pad thickness monthly - they should be replaced when below 7mm.

[IsaacLee]

This issue is frequently discussed in automotive forums. It actually involves three common sound sources: the mechanical noise from brake pad retraction calipers, the pressure relief sound of the hill start assist system, and the gear engagement noise when shifting the transmission. My American car always makes a clunking sound in winter, which I later found out was caused by the brake pads contracting in the cold. Remember to drive for a while after washing the car to dry the brakes. If accompanied by a sharp metal sound, it indicates that the wear indicator should be replaced. Failing to address this promptly can scratch the brake discs.