Common causes of car brake judder

　　Steering wheel or body shake during vehicle braking is a common problem encountered by drivers. This issue not only affects the driving experience but may also indicate a safety hazard. The root cause is often related to the condition of the braking system's mechanical components, installation accuracy, and material properties.

　　One of the core causes of braking shake is deformation or uneven wear of the brake disc. As the core component of braking friction, the brake disc may become uneven due to high-temperature annealing, external impact, or manufacturing defects after prolonged use. When the brake disc edge becomes uneven or the radial runout exceeds the standard, uneven friction force distribution during braking will cause periodic vibrations, manifesting as shaking of the steering wheel or pedal. In addition, the fit between the brake pads and the brake disc is crucial; insufficient contact area or the presence of hard particles will also trigger shaking due to local friction differences.

　　Assembly problems in the braking system should not be overlooked. For example, poor brake caliper piston retraction, insufficient lubrication of the guide pins, or loose caliper mounting brackets may cause the braking force output direction to shift, resulting in unbalanced force. In older vehicles, calipers that have not been maintained for a long time tend to accumulate rust and dirt, increasing component movement resistance and further amplifying the shaking phenomenon.

　　It is worth noting that some shaking originates from the combined influence of the tires and suspension system. If the vehicle's four-wheel alignment data deviates excessively, such as caster misalignment or abnormal camber, the direction of wheel force during braking may conflict with the design specifications, leading to additional vibrations. At the same time, tire imbalance or wheel hub deformation can also be transmitted to the braking system through the chassis, forming a composite shake.

　　From a materials science perspective, the material compatibility of the brake disc and brake pads directly affects braking stability. Low-quality brake pads have poor thermal fade performance, and the friction coefficient changes drastically at high temperatures, easily causing instantaneous braking force fluctuations. If cast iron brake discs have not undergone compliant heat treatment, residual internal stress may lead to the expansion of micro-cracks, ultimately manifesting as braking shake.

　　Solving these problems requires systematic troubleshooting. It is recommended to prioritize checking the brake disc flatness and brake pad wear condition, and if necessary, perform disc machining or replace parts with original specifications. At the same time, the caliper operating status, tire balance, and four-wheel alignment parameters should be checked simultaneously to avoid the persistence of other related problems after a single repair. For vehicles that frequently experience braking shake, it is recommended to establish a periodic maintenance record to prevent chain reactions caused by component aging.

　　While braking shake is a common fault, its causes are complex and involve the cooperation of multiple systems. Through accurate diagnosis and standardized maintenance, comfort and safety can be effectively restored, and the service life of components can be extended.