Why Do Automotive Brake Pads Wear Unevenly? Caliper Slides Frozen

Uneven brake pads wear is a common problem with braking systems and can cause safety concerns. During any brake job when removing the brake pads you may notice that one brake pad is severely worn while the opposite pad in the caliper looks relatively unused, this is the first sign there is a problem. In this guide we show you why this problem occurs and what to do to fix it, we address this issue in the order of popularity.

Single Piston Caliper

1. Contrary to what you may think it is not the caliper piston that is causing the problem. Here is what a typical brake caliper mounting bracket and brake pad carrier looks like.

2. The number one cause for uneven brake pad wear is seized or poorly lubricated caliper slides. This condition will not allow the brake caliper to "float" freely which will cause uneven brake pad wear. The slides must be removed, cleaned and lubricated with brake grease at each brake job service interval.

3. Brake pads are held in place by anti-rattle clips which can become worn or corroded, not allowing the pads to move freely which can cause the pads to "stick" inside the caliper mount, these should replaced with each brake service to prevent irregular pad wear.

Note: Some floating calipers can have two pistons but are still subject to the same troubles.

Multi Piston Caliper

A multi-piston brake caliper is fixed and does not "float" and if the brake pads are wearing unevenly there are only two causes for this condition.

1. Inside the brake caliper there will be two or four pistons which if one or more of the pistons experience internal rust or corrosion causing the piston to seize inside the caliper housing, the only fix for this is to replace or rebuild the brake caliper.

2. Again, the caliper brake pad anti rattle clips can cause the brake pads to get "hung up" in the brake pad carrier which will force the brake pads against the brake rotor and cause residual wear.

Preventing Uneven Brake Pad Wear

Preventing uneven brake pad wear is not difficult and is apart of the regular vehicle maintenance schedule. To help the brake caliper stay in good working order it is advised to bleed and flush the brake system to help prevent moister from building up inside the caliper and causing the caliper pistons to seize inside the housing. Also, most new brake pads include brake service grease and new pad anti rattle clips which should be used at the time of a brake service.

Watch the Video!

Please watch this video of the job being done to glean additional helpful information.

Credits

This guide knowledge base was created by the 2CarPros Team, and by Ken Lavacot: Automobile repair shop owner and certified master automobile technician of over 30 years. If you have question or need help please ask one of our experts we are happy to help. Please visit our 2CarPros YouTube Channel.