US Dollars
Calipers & Master Cylinder
Calipers & Master Cylinder Rebuild Kits
Fix sticky brake calipers, fluid weeping, and low lever pressure with high-density caliper and master cylinder rebuild kits. Operating down by the hubs exposes brake calipers to intense heat and constant dust, causing internal square-section fluid seals to crack and seize. Restore factory-smooth hydraulic pressure with our complete replacement pistons, oil-resistant EPDM rubber dust seals, master cylinder plunger assemblies, slider pin boots, and high-pressure replacement bleeder valves.
What are the primary symptoms of a failing master cylinder internal piston seal?
The classic indicator of an internal master cylinder seal leak is a brake lever that slowly creeps or bleeds down all the way to the handlebar grips while you are maintaining steady stopping pressure at a complete stop. This happens because the internal rubber cup seals have worn out or scored, allowing high-pressure brake fluid to bypass the piston and loop back into the reservoir reservoir.
What happens when a brake caliper piston seal begins sticking?
The internal square-section seal is responsible for physically pulling the caliper piston back a fraction of a millimeter when you release the brake lever. When road salt, mud, or brake dust builds up behind the seal, it pinches the piston, causing the brake pads to constantly drag against the moving rotor. This creates extreme friction heat, premature pad wear, and significant drivetrain drag.