Common reasons for brakes sticking include worn caliper slides, leaky caliper bolts, torn caliper piston boots and worn brake hoses. With the exception of worn or leaky brake hoses, most sticky brake problems are relatively easy to diagnose and quick and inexpensive to repair. Identifying a problem with the brake hose usually requires putting the vehicle on a lift and then testing the steering and braking systems.
The brake's caliper slides are grooves that allow the brake pads to slide in and out smoothly when the driver operates the brake pedal. Over time, the caliper grooves get corroded or dirty, or the pads get stuck in the grooves. Fixing this problem usually requires disassembling the caliper and cleaning it thoroughly.
Each of the caliper's two bolts has a protective rubber or silicone gasket that keeps lubricant inside of the caliper. Because these gaskets are quite fragile, careless or rough mechanics often unintentionally break them. When the gaskets break, lubricant leaks out of the caliper, causing rust and corrosion that can make brakes stick. Depending on parts availability and the amount of rust inside the caliper, fixing this problem requires replacing either the bolts or the entire caliper.
A caliper's piston is wrapped in a rubber boot that seals in lubricant and seals out dirt, grime and dust. As with the bolt gaskets, this boot tears easily when replacing brake pads or other components. Unfortunately, repairing or replacing a rusted cylinder is usually impossible, so fixing this problem typically requires replacing the entire caliper.