Dorman M630440 Brake Master Cylinder

Reliable Brake Master Cylinder for Buick, Chevrolet, GMC, and Saab

The Dorman M630440 Brake Master Cylinder is engineered to restore proper brake hydraulics for select Buick, Chevrolet, GMC, and Saab models. Designed with precision, this master cylinder includes a reservoir and sensor to ensure optimal brake system performance.

• Master cylinder bore diameter: 1.063 inches for accurate hydraulic pressure
• Constructed from durable aluminum material for corrosion resistance
• Includes reservoir and sensor for complete brake system integration
• Two outlets with secondary outlet thread diameter of 0.5 inches
• Rearward outlet size: 1/2-20 for secure brake line connections
• Compatible with Buick 9-7x, Chevrolet Trailblazer, Trailblazer EXT, GMC Envoy, Envoy XL, Rainier, and Saab 9-7x

Product Details and Specifications

The Dorman M630440 master cylinder is designed to meet the exact specifications required for brake hydraulics in multiple GM and Saab SUVs. Its aluminum construction provides strength and resistance to wear, while the included reservoir and sensor ensure the brake fluid is properly monitored and maintained. The 1.063-inch bore diameter supports consistent hydraulic pressure, critical for safe braking performance. Featuring two outlets, including a rearward outlet sized at 1/2-20, this master cylinder facilitates secure and reliable brake line connections.

Compatible Vehicles and Applications

This brake master cylinder is compatible with the following vehicles:

• Buick 9-7x
• Chevrolet Trailblazer and Trailblazer EXT
• GMC Envoy, Envoy XL, and Rainier
• Saab 9-7x

It is designed specifically for brake hydraulic systems requiring a master cylinder with the listed bore diameter and outlet specifications.

Common Brake System Issues Addressed

• Brake pedal sinking or sponginess due to master cylinder failure
• Brake fluid leaks from worn or damaged master cylinder seals
• Inconsistent brake pressure affecting stopping performance
• Warning lights triggered by faulty brake fluid level sensors
• Brake system contamination from reservoir damage or cracks

Installation Notes and Tips

Installation of the Dorman M630440 master cylinder requires careful attention to brake fluid handling and bleeding procedures. Note that mounting hardware is not included and must be reused or sourced separately. Ensure all brake lines are properly connected to the two outlets, including the rearward outlet sized 1/2-20. Verify sensor connections for accurate brake fluid level monitoring. After installation, perform a thorough brake bleed to remove air from the system and confirm proper pedal feel.

Quality Assurance and Warranty

Dorman manufactures this brake master cylinder to meet or exceed OEM standards for fit, form, and function. The aluminum construction and integrated sensor contribute to long-term reliability. While specific warranty details are not provided here, Dorman typically offers limited warranties on their brake hydraulic components. Consult product documentation or the manufacturer for exact warranty terms.