Dorman M39531 Brake Master Cylinder

Reliable Brake Master Cylinder for Ford and Mercury Vehicles

The Dorman M39531 brake master cylinder is engineered to restore proper brake hydraulics in select Ford and Mercury models. Designed with a durable cast iron construction and a 21mm bore diameter, this master cylinder ensures consistent braking performance for vehicles like the Mustang, Thunderbird, and Grand Marquis.

• Cast iron master cylinder material for durability
• 21mm bore diameter for precise hydraulic pressure
• Includes reservoir for fluid containment
• Two outlet ports with rearward outlet size 1/2-20 and secondary outlet thread diameter 9/16-18
• Compatible with Ford Capri, Cougar, Grand Marquis, LTD, Marquis, Mustang, and Thunderbird
• Part number M39531 for accurate identification

Product Details and Specifications

This Dorman brake master cylinder (part number M39531) features a cast iron body that withstands the rigors of brake system pressure and heat. The 21mm bore diameter is calibrated to provide the correct hydraulic force needed for effective braking. The included reservoir simplifies installation by providing a ready-to-use fluid container. With two outlets, including a rearward outlet sized at 1/2-20 and a secondary outlet thread diameter of 9/16-18, this master cylinder is designed to integrate seamlessly with the brake hydraulics of compatible Ford and Mercury vehicles.

Compatible Vehicles and Applications

This master cylinder is compatible with a range of Ford and Mercury models, including:

• Ford Capri
• Ford Cougar
• Ford Mustang
• Ford Thunderbird
• Mercury Grand Marquis
• Mercury LTD
• Mercury Marquis

Use the Dorman M39531 to replace worn or failing master cylinders in these vehicles to maintain safe and reliable braking performance.

Common Issues Addressed by This Master Cylinder

• Spongy or unresponsive brake pedal
• Brake fluid leaks from the master cylinder or reservoir
• Reduced braking efficiency or uneven brake pressure
• Brake warning light activation due to hydraulic failure
• Contaminated or damaged brake fluid reservoir

Installation Notes and Tips

• Ensure the brake system is properly bled after installation to remove air pockets
• Check compatibility with your vehicle’s brake line fittings before installation
• Use appropriate brake fluid as specified by the vehicle manufacturer
• Inspect mounting points and hardware; note that mounting hardware is not included
• Follow all safety precautions when working with brake hydraulics

Quality Assurance and Warranty

Dorman manufactures the M39531 brake master cylinder to meet or exceed OEM standards for fit and function. The cast iron construction and precise bore diameter contribute to long-lasting performance. While mounting hardware is not included, the product is backed by Dorman’s quality control processes. Please refer to Dorman’s warranty policy for specific coverage details.