Dorman M39871 Brake Master Cylinder

Reliable Brake Master Cylinder Replacement

The Dorman M39871 brake master cylinder is engineered to restore proper brake hydraulics performance in compatible vehicles. Designed with a durable cast iron construction and a 1.25-inch bore diameter, this master cylinder supports consistent brake pressure for safe stopping power.

• Cast iron master cylinder material for durability
• 1.25-inch bore diameter for precise hydraulic control
• Two outlet ports with M10 x 1.0 rearward outlet thread size
• Includes master cylinder only; reservoir and mounting hardware not included
• Thread pitch of 1.0 for secure hydraulic line connections

Product Details and Specifications

The Dorman M39871 brake master cylinder features a cast iron body designed to withstand the rigors of brake system pressure and heat. Its 1.25-inch bore diameter ensures proper fluid displacement to maintain brake responsiveness. The unit includes two outlets, with the secondary outlet thread diameter measuring 10 mm and a rearward outlet size of M10 x 1.0, compatible with standard brake line fittings. This master cylinder does not include a reservoir or sensor, focusing solely on the hydraulic control component. The thread pitch of 1.0 ensures compatibility with corresponding brake line threads for a secure fit.

Compatible Vehicles and Applications

This brake master cylinder is suitable for replacement in various vehicle makes and models requiring a 1.25-inch bore diameter master cylinder with dual outlets and M10 x 1.0 thread specifications. It is commonly used in brake hydraulic systems where a cast iron master cylinder is specified. For example, it is compatible with certain Ford, Chevrolet, and Dodge models that utilize similar brake master cylinder configurations. Always verify fitment with your vehicle's specifications before purchase.

Common Brake System Issues Addressed

• Brake pedal sinking or sponginess due to master cylinder wear
• Brake fluid leaks from worn or damaged master cylinder seals
• Reduced braking efficiency caused by internal master cylinder failure
• Inconsistent brake pressure affecting vehicle stopping distance
• Brake warning light activation related to hydraulic pressure loss

Installation Notes and Tips

Installation of the Dorman M39871 master cylinder requires proper brake system bleeding to remove air and ensure optimal hydraulic performance. Since mounting hardware and reservoir are not included, reuse existing components or source compatible parts separately. Verify thread pitch and outlet sizes to match brake lines. It is recommended to inspect brake lines and related components during installation for wear or damage.

Quality Assurance and Warranty

Dorman brake master cylinders are manufactured to meet or exceed OEM standards for fit, form, and function. The M39871 part number undergoes rigorous quality control to ensure reliable operation within brake hydraulic systems. Please consult Dorman's warranty policy for specific coverage details.