Restoring the mobility of the front brake cylinder piston (Audi A4 B6)

Corrosion on the sliding surfaces of the brake caliper will make it difficult for the caliper parts to move. If the dust seal is defective or poorly installed, dirt and moisture may penetrate into the brake cylinder piston, and the piston may also get stuck in the caliper.

1. Remove the brake pads. The caliper body can only be cleaned with alcohol. The adhesive surface for the brake pad must be cleaned of any adhesive or grease residue.

2. Check the free movement of the linings in the guides. If the linings are jammed, clean the guides with a screwdriver, but do not damage the piston cuff. Before inserting the linings, apply a small amount of copper grease (the lubricant should not get on the working surfaces of the brake discs and linings).

3. The brake caliper should also move freely, otherwise clean the guide pin. To keep the sliding points mobile, apply a small amount of heat-resistant grease to them.