Dorman M39448 Brake Master Cylinder

Reliable Brake Master Cylinder for Jeep CJ5, CJ7, and Scrambler

The Dorman M39448 brake master cylinder is engineered to restore proper brake hydraulics in Jeep CJ5, CJ7, and Scrambler models. Designed with durable cast iron and a built-in reservoir, this master cylinder ensures consistent brake fluid delivery for safe and effective braking performance.

• Master cylinder bore diameter: 0.938 inches for precise hydraulic pressure
• Constructed from cast iron for long-lasting durability
• Includes reservoir for brake fluid storage
• Two outlet ports with rearward outlet size 1/2-20 and secondary outlet thread diameter 9/16-18
• Compatible with Jeep CJ5, CJ7, and Scrambler brake systems

Product Details and Specifications

The Dorman M39448 brake master cylinder features a 0.938-inch bore diameter, which is critical for maintaining the correct hydraulic pressure in the brake system. Its cast iron construction provides strength and resistance to wear, making it suitable for the demanding conditions faced by Jeep CJ5, CJ7, and Scrambler vehicles. The integrated reservoir simplifies brake fluid management, while the two outlet ports with specific thread sizes (rearward outlet 1/2-20 and secondary outlet 9/16-18) ensure compatibility with the original brake lines. This master cylinder does not include mounting hardware or sensors, so verify existing components before installation.

Common Applications and Problem Resolution

• Restores brake fluid pressure in Jeep CJ5, CJ7, and Scrambler models
• Replaces worn or leaking master cylinders causing brake pedal sponginess
• Addresses brake fluid reservoir leaks or contamination issues
• Resolves inconsistent braking performance due to internal cylinder wear
• Supports brake system rebuilds requiring OEM-style master cylinder replacement

Installation Notes and Tips

Before installing the Dorman M39448 master cylinder, ensure the brake system is properly bled to remove air pockets. Confirm that the existing mounting hardware is compatible, as this product does not include it. Use the correct thread sizes for brake line connections: 1/2-20 for the rearward outlet and 9/16-18 for the secondary outlet. Follow manufacturer torque specifications to avoid damage during installation.

Quality Assurance and Warranty

Dorman manufactures the M39448 brake master cylinder to meet or exceed OEM standards for Jeep CJ5, CJ7, and Scrambler vehicles. The cast iron construction and precise bore diameter contribute to reliable brake system performance. While specific warranty details are not provided, Dorman products typically come with a limited warranty against defects in materials and workmanship.