Dorman M390363 Brake Master Cylinder

Reliable Brake Master Cylinder for Chevrolet and GMC Vans

The Dorman M390363 Brake Master Cylinder is designed to restore proper brake function in Chevrolet Express 1500, Express 2500, GMC Savana 1500, and Savana 2500 models. Engineered with durable aluminum and featuring a 1.125-inch bore diameter, this master cylinder includes a reservoir to ensure consistent hydraulic pressure for safe braking performance.

• Master cylinder bore diameter: 1.125 inches for precise hydraulic control
• Constructed from aluminum for corrosion resistance and durability
• Includes reservoir for fluid storage and management
• Two outlet ports with rearward outlet size 1/2-20 and secondary outlet thread diameter 9/16-18
• Compatible with Chevrolet Express 1500/2500 and GMC Savana 1500/2500

Product Details and Specifications

This Dorman brake master cylinder (part number M390363) is manufactured from aluminum, providing a lightweight yet robust component that resists rust and wear. The 1.125-inch bore diameter is designed to deliver consistent hydraulic pressure to the brake system. The included reservoir allows for proper brake fluid containment and circulation. With two outlets, including a rearward outlet sized 1/2-20 and a secondary outlet with a 9/16-18 thread diameter, this master cylinder supports the brake hydraulics system requirements of the specified Chevrolet and GMC van models.

Applications and Common Repair Uses

• Restores brake pressure loss in Chevrolet Express 1500 and 2500 vans
• Replaces worn or leaking master cylinders in GMC Savana 1500 and 2500
• Addresses brake fluid leaks or reservoir damage
• Solves issues with inconsistent brake pedal feel or sponginess
• Supports brake system rebuilds requiring a new master cylinder

Installation Notes and Tips

Installation of the Dorman M390363 master cylinder requires proper brake system bleeding to remove air and ensure optimal hydraulic function. Note that mounting hardware is not included, so existing hardware should be inspected and replaced if necessary. Verify compatibility with Chevrolet Express and GMC Savana models before installation. Use appropriate tools to avoid damage to outlet threads and reservoir connections.

Quality Assurance and Warranty Information

Dorman manufactures this brake master cylinder to meet or exceed OEM specifications for fit and function. The aluminum construction offers corrosion resistance for extended service life. While mounting hardware is not included, the product undergoes quality checks to ensure reliability. Warranty details can be obtained from the product documentation or manufacturer directly.