Dorman M39630 Brake Master Cylinder OEM Replacement 1.250 in. Bore

The Dorman M39630 is a 100% new OEM-replacement brake master cylinder engineered for select Chevrolet and GMC van and chassis cab applications. Designed to match the original equipment in form, fit, and function, this unit restores proper hydraulic braking performance without the concerns associated with remanufactured cores.

The cylinder housing is cast to match the original part's material composition, while all internal rubber components are manufactured from high-quality EPDM compound for long-lasting resistance to glycol-based brake fluids. With a 1.250 in. (40 mm) primary bore and dual outlet ports (1/2 in.-20 and 9/16 in.-18), this master cylinder is designed for power brake compatible systems.

Key Features:

• Precise replacement – cylinder housing matches the casting material of the original part for consistent performance
• EPDM rubber components – resistant to glycol-based brake fluid for extended service life
• 100% new construction – not remanufactured, ensuring highest quality and safety standards
• SAE International compliant – manufactured to meet rigorous SAE specifications
• Power brake compatible – designed for use with power-assisted brake systems
• Bore size: 1.250 in. / 40 mm
• Outlet 1: 1/2 in.-20 | Outlet 2: 9/16 in.-18
• UPC: 082702399569

Dorman has been a trusted name in the automotive aftermarket for over 100 years, delivering tens of thousands of replacement parts engineered to save time, reduce repair costs, and restore vehicle reliability.