1. Brake pedal jitter: usually drive the new car after a few hundred miles or replace new brake discs of a mileage,

 caused by brake disc face runout tolerance exceeds bid brake pump back, form a cyclical hydraulic back effect, 

at the same time due to the high temperature pulse brakes, the brake plate of internal stress release, causing the

 brake plate deformation, cause the brake pedal jitter and the steering wheel vibration.

2. Rust: the rusting of the brake disc is caused by the long-term storage of the vehicle. In addition, some of the rust

 is caused by the chemical action of salt gravel, which makes the surface of the brake disc rough and uneven and 

affects the braking effect.

3. Brake offset: due to thick road dust, grease, brake debris and basic rust, a layer of friction coefficient is often 

different from the previous surface layer, resulting in unequal friction between the corresponding two wheel brake 

discs, causing the brake to run off, and sometimes accompanied by sharp noise.