Dorman M39440 Brake Master Cylinder

Reliable Brake Master Cylinder for GM Vehicles

The Dorman M39440 Brake Master Cylinder is engineered to restore proper brake hydraulics for select Buick, Cadillac, Chevrolet, Oldsmobile, and Pontiac models. Designed with precision, this master cylinder ensures consistent brake fluid pressure and reliable stopping power.

• Includes reservoir and sensor for complete brake system integration
• Dual bore diameters of 0.938 and 1.25 inches for balanced hydraulic performance
• Constructed from durable aluminum for corrosion resistance and longevity
• Equipped with five outlets, including rearward outlet sizes M10 x 1.0, M13 x 1.5, and M16 x 1.5
• Compatible with multiple GM models such as Buick Century, Cadillac DeVille, Chevrolet Celebrity, Oldsmobile Cutlass Ciera, and Pontiac 6000

Technical Details and Specifications

The Dorman M39440 master cylinder features a dual bore design with diameters of 0.938 and 1.25 inches, optimizing hydraulic pressure distribution for improved brake response. Its aluminum construction offers enhanced durability and resistance to corrosion, critical for maintaining brake system integrity over time. The included reservoir and sensor facilitate seamless integration with the vehicle’s brake fluid monitoring system. With five outlets, including rearward outlet thread sizes M10 x 1.0, M13 x 1.5, and M16 x 1.5, this master cylinder supports complex brake line configurations found in various GM vehicles.

Compatible Vehicles and Applications

This brake master cylinder is compatible with a range of General Motors vehicles, including:

• Buick Century
• Cadillac DeVille and Fleetwood
• Chevrolet Celebrity
• Oldsmobile Cutlass Ciera
• Pontiac 6000

It is designed to meet the specific hydraulic requirements of these models, ensuring proper fit and function.

Common Brake System Issues Addressed

• Brake pedal sinking or sponginess due to master cylinder wear
• Brake fluid leaks from a failing master cylinder reservoir or seals
• Inconsistent brake pressure causing uneven braking performance
• Brake warning light activation related to sensor failure
• Corrosion or damage to the original aluminum master cylinder body

Installation Notes and Tips

• Ensure the brake system is fully depressurized before removal
• Bleed the brake system thoroughly after installation to remove air
• Verify outlet thread sizes match vehicle brake line fittings (M10 x 1.0, M13 x 1.5, M16 x 1.5)
• Check sensor connections for proper electrical integration
• Use recommended brake fluid type as specified by the vehicle manufacturer

Quality Assurance and Warranty

Dorman manufactures the M39440 master cylinder to meet or exceed OEM standards for fit, form, and function. The aluminum construction and included sensor contribute to reliable brake system performance. While specific warranty details vary, Dorman typically offers a limited warranty covering defects in materials and workmanship to provide confidence in product durability.