How Do You Rebuild A Hydraulic Master Cylinder?

Hydraulic master cylinders (m/c) are a crucial part of a hydraulic brake system. They mount the reservoir that holds a surplus of fluid and house the piston, which, when actuated by hand (or foot) pressure either directly or augmented by a vacuum booter, supplies hydraulic pressure to the brake calipers and wheel cylinders. Hydraulic brake fluid that is contaminated with dirt or other hard particulates can destroy the piston seals and score the cylinder, leading to brake fade and failure. The rubber piston seals also may be damaged by using the wrong fluid and even old age. Wipe the m/c down with a clean shop rag to remove any dirt and debris from the outside. Remove the m/c cap and discard the old fluid. Remove the brake lines from the m/c with a flare-nut wrench and capture any escaping fluid with a clean rag. Remove the bolts or nuts holding the m/c in place and pull it from the vehicle. Look into the open end of the m/c and locate the retaining (snap) ring. Carefully remove the ...  more