What are the causes of uneven brake pad wear?
3 Answers
Main causes of uneven brake pad wear: 1. Frequent braking during turns creates unbalanced force distribution between left and right wheels, leading to inconsistent wear; 2. Possible deformation of one side's brake disc; 3. Inconsistent return of brake caliper pistons, such as when one side's caliper guide pin gets stuck; 4. Significant differences in length or diameter between left and right brake fluid lines. Other contributing factors: 1. Wear rate is primarily determined by brake disc and pad materials, so inconsistent pad material composition could be a factor; 2. The sliding pins are sealed with rubber boots, but if contaminated with water or lacking lubrication, they won't retract properly, causing the outer pad to maintain contact with the rotor and accelerate wear; 3. Asynchronous braking between left and right brake assemblies.
I have personal experience with this issue. Last time, I encountered a situation where one brake pad was wearing out quickly while the other looked almost new. After inspection, it turned out to be a problem with the caliper piston not retracting properly, causing one side to constantly drag. The guide pins were also problematic—if they lack sufficient lubrication, they can get stuck, preventing the brake pads from retracting. Additionally, if the brake disc is warped or has uneven thickness, the contact surface won't be even. In my case, the uneven disc surface caused uneven wear. Proper installation is also crucial; the brake pads must be positioned correctly without any misalignment, or else uneven wear can occur. If you notice the car pulling to one side when braking or hear squeaking noises, don't delay—check the brake pad wear immediately.
We often encounter uneven wear cases during maintenance. The most common issue is with the caliper - if the piston retracts slowly, it will continuously grind on the same side. The slide pins are crucial; if they're rusted or lack lubrication, they'll get stuck. Another situation is when the brake disc runout exceeds standards, simply put, the disc doesn't rotate properly. I've also encountered poor-quality brake pads where the two pieces had different hardness levels, naturally leading to uneven wear. Driving habits also play a role - some people frequently brake hard during turns, which easily causes one-sided wear. It's recommended to check the lubrication condition of guide pins every 20,000 kilometers and measure the thickness difference of brake discs while at it.
