Rear Brake Master Cylinder - Vespa GTS 250/300

Vespa GTS 250/300 Rear Master Cylinder

Don't compromise on safety with a spongy or leaking brake lever. Over time, internal seals in your master cylinder can perish, leading to inconsistent braking pressure and dangerous fluid leaks. This high-quality aftermarket replacement restores that crisp, "factory-fresh" lever feel and ensures your Vespa GTS has the reliable clamping force needed for heavy city traffic and high-speed touring.

Key Features

• OEM-Spec Performance: Manufactured to meet or exceed original Piaggio specifications for a direct, "no-fuss" swap.

• Precision Bored: Features a high-tolerance internal cylinder for smooth piston travel and consistent hydraulic pressure.

• Durable Housing: Cast from high-strength alloy to withstand high-pressure braking cycles and environmental corrosion.

• Pre-Assembled: Comes with the internal piston and seal kit pre-installed, saving you the headache of a complex rebuild.

Fitment Guide

Technical Specs

• Part Number: CM074901-AFT

• Material: Cast Aluminum Alloy

• Position: Left-Hand Side (Rear Brake)

• Compatibility: DOT 4 or DOT 5.1 Brake Fluid (Consult Manual)

Maintenance Note: Brake fluid is hygroscopic (absorbs water). If your old master cylinder failed due to internal corrosion, ensure you perform a complete system flush with fresh DOT 4 fluid to prevent the new unit from fouling.

Installation Tip: Always use new copper crush washers on the banjo bolt. Reusing old washers is the #1 cause of slow leaks at the master cylinder connection.

Pro Tip: Vacuum bleeding is highly recommended for the GTS series. Because of the long brake line run from the handlebar to the rear caliper, getting all the air out manually can be a time-consuming process.

You can also purchase this part through your local Genuine dealer.

WARNING: California Proposition 65