BMW 34111101844 Right Brake Caliper

With the caliper removed, carefully withdraw the dust excluders from the ends of the pistons. Hold one of the pistons depressed and apply air from a tyre pump to the fluid inlet hole to eject the piston not being held. Prise out the piston seal from the groove in the cylinder, taking great care not to scratch the metal surfaces, then discard the seal and obtain a repair kit. Fit the new seal using fingers only to manipulate it, dip the piston in clean hydraulic fluid, and insert it squarely into the cylinder bore. Hold this reconditioned piston depressed, apply air pressure to the fluid inlet hole, and eject the second piston. Repeat the operations to renew the seal and insert the piston into its bore. Install new dust excluders to the ends of the pistons. If any scratches, scoring, or 'bright' wear areas are observed on the surfaces of the piston or cylinder bores during the overhaul operations, the caliper must be renewed complete.