Rick's Free Auto Repair Advice

Uneven brake pad wear and noise

What causes Uneven brake pad wear and noise

Rear disk brakes are exposed to the same road debris, salt, snow, rain, and heat as front brakes. But because they do only 20% of the braking, they don’t get worn as quickly. That leaves them especially vulnerable to the elements. Since the pads don’t wear as quickly, the caliper doesn’t slide on the caliper pins nearly as far, so caliper pin rusting is far more common. This is especially true in 2000-06 Chevrolet Silverado, Avalanche, and Suburban 1500 trucks.rusted caliper pin, Chevrolet Silverado, Alavance, Chevrolet Suburban

Every time a caliper slides on the pins, air is either expelled or sucked in. Some manufacturers install a rubber cup over the air breathing hole to allow air to flow but keep out water and road debris. In the Chevrolet design, GM drilled pin holes in the bracket and covered them with rubber bushings. Unfortunately, those rubber bushing aren’t doing the job and the rear caliper pins are rusting and seizing in the bracket. When that happens, the caliper can’t slide and applies braking pressure to only the inboard pad. The result is uneven braking, noise, vibration, and loss of stopping power.

Even though this is a problem on GM trucks, it can happen to any vehicle. I’ve seen caliper pins so frozen in the bracket that the only option is to replace the entire mounting bracket. In fact, this is happening so often that rebuilders are now selling rebuilt brackets

Caliper bracket, caliper pin, caliper, rear caliper, Chevrolet Silverado

Buy a rebuilt caliper bracket to correct rusted and seized caliper pins

so you don’t have to buy a complete caliper.

One way to avoid this problem is to service the rear calipers about once a year. Retract the rear caliper piston slightly with a special Lisle 25000 caliper tooltool (see below). Then remove the caliper. Grease the slide pins with Permatex synthetic brake grease and reinsert the caliper pins. Also apply the grease to the abutment areas where the pads slide

 

© 2012 Rick Muscoplat

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Posted on by Rick Muscoplat



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