Restoration of the mobility of the brake caliper and piston

With a defective or carelessly installed dust seal, dirt and moisture can enter the hydraulic cylinder. Over time, the sliding piston rusts slowly but surely. Consequences: high wear of brake linings and discs, uneven braking effect.

Stages of work

Remove or mount the brake pads as described above.

Check the mobility of the lining in the mines. If necessary, clean with a stiff toothbrush or medium slotted screwdriver and blow with compressed air. Do not damage or move the dust collars during operation. Before installing the brake pads, put some lubricating paste (copper-containing) to contact surfaces.

The brake calipers must have free play. If not, clean the sliding surfaces as described above and lightly lubricate with heat resistant copper paste.

Checking the brake pistons

Before checking the mobility of the brake piston, install a clamp with a wooden block as a stop on the brake caliper. So you protect the piston from damage - it will not be able to completely slide out of the cylinder. Of course, the opposite brake caliper must remain completely mounted.

Have your assistant gently press the brake pedal. If the piston jams, it must pump the pedal until its mobility is restored. After that, press the piston with the mounting lever into the cylinder. Repeat the procedure until the piston slides freely in the cylinder.

Attention: if it was not possible to succeed, let it be better to repair the caliper in a specialized workshop.

Replacing the dust collar

Pry up the dust boot from the brake caliper and sliding piston with a bent welding wire or a small angle screwdriver. Do not scratch the working surfaces of the sliding piston and cylinder!


Pay attention to whether the brake fluid comes out of the cylinder. In this case, it is better to repair the caliper in the workshop.

Clean the sealing surfaces with denatured alcohol or clean brake fluid. Before you mount a new seal, preserve the cleaned surfaces with brake cylinder paste (Ate, Bosch, Girling).

Gently press the new dust seal against the sealing surfaces. Be sure to make sure that it fits snugly.

Press the piston into the cylinder until it stops.

Mount the brake pads as described above.

After completing the work, check the brake fluid level and the tightness of the brake system.