Speaking of abnormal noise, the first thing that comes to mind is the various abnormal noises of the brake system. There are many reasons for these abnormal noises. Now I organize them and share them with you. I hope that these annoying brake system abnormal noises will no longer annoy the maintenance colleagues, nor make the car owners annoyed, and no longer let these problems become car owners making fun The reasons and excuses of maintenance colleagues "A brake abnormal sound can't be done...".

First of all, you have to distinguish the sound of abnormal noise, whether it is screaming, muffled, or screaming. Scream, first check that the brake pads are almost used up (the alarm pad sounds). If it is a new disc, check whether a brake disc and the disc are completely consistent. Silence is a problem with the brake calipers, such as wear of movable pins and falling off of spring plates. There are more problems with the slightest call. The calipers, brake discs, and brake pads may all have problems. If it continues to sound, first check whether there is a drag brake. Poor caliper reset will cause long-term friction between the disc and the disc. It depends on whether the brake disc is grooved, because local friction will cause abnormal noise. If there is no problem with the disc, then consider whether the brake pads are too hard or the pads are installed incorrectly.

Mechanism of braking noise

The mechanism of brake squeal is caused by self-excited vibration. The frictional excitation between the brake disc and the friction material provides energy for the entire braking system. The energy is transmitted between the entire brake assembly and the connected suspension and chassis components and generates a vibration response. When braking squeal occurs, system vibrations of extremely high amplitude are generated.

The main influencing factors of braking noise:

(1) Brake pads, friction pad materials, friction pad structure, friction coefficient, caliper compressibility, noise damping pads, friction material chamfering, steel back dimensional tolerance structure;

(2) Material and structure of the brake disc;

(3) The structure of the brake caliper bracket and the structure of the brake caliper housing;

(4) Material and structure of steering knuckle, bearing and wheel bracket;

Any of the above products that do not meet the requirements will produce braking noise. Take Audi as an example:

Audi model brake abnormal noise classification

Abnormal brake noise caused by damage to the stop spring of the front brake caliper:

Abnormal sound description: creaking, creaking, rattling, clattering, clattering, metal knocking in the front wheel area when braking or driving on uneven roads

Main models: Audi all series (domestic models)

The cause of the failure: the front brake caliper stop spring is broken

Repair method: replace the stop springs of the left and right brake calipers of the front axle at the same time