The best thing to do is replace the caliper with a remanufactured unit. The time involved with rebuilding and the cost of the materials tto do it is more than it's worth. The usual causes for premature caliper failure is not flushing the brake fluid on a yearly basis.

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ASE Master Technician, Lead Technician for Deutsch American Inc. Over 6 years of Import experience-specializing in German Automobiles.