Dorman M390320 Brake Master Cylinder

Reliable Brake Master Cylinder for Chevrolet and GMC Vehicles

The Dorman M390320 Brake Master Cylinder is engineered to restore proper brake function in select Chevrolet, GMC, Isuzu, and Oldsmobile models. Designed with precision, this master cylinder ensures consistent hydraulic pressure for safe and effective braking performance.

• Compatible with Chevrolet Blazer, GMC Jimmy, S10, S15, Sonoma, and related models
• Dual bore diameters: 24mm and 36mm for balanced brake pressure
• Constructed from durable aluminum for corrosion resistance and longevity
• Includes reservoir for brake fluid storage
• Two outlet ports with rearward outlet size 1/2-20 and secondary outlet thread diameter 9/16-18
• Package contains the master cylinder only; mounting hardware not included

Product Details and Specifications

The Dorman M390320 master cylinder features dual bore diameters of 24mm and 36mm, which help maintain proper hydraulic pressure distribution between front and rear brakes. Its aluminum construction offers strength and resistance to corrosion, making it suitable for long-term use in brake hydraulic systems. The included reservoir allows for efficient brake fluid management, while the two outlets with specified thread sizes ensure compatibility with factory brake lines. This master cylinder is designed specifically for vehicles such as the Chevrolet Blazer, GMC Jimmy, Isuzu Hombre, Oldsmobile Bravada, and various S-series trucks including the S10 and S15 models.

Common Applications and Problem Resolution

• Restores brake pedal firmness and responsiveness
• Eliminates brake fluid leaks from a worn or damaged master cylinder
• Resolves uneven braking caused by internal seal failure
• Prevents brake system failure due to master cylinder wear
• Addresses brake warning light issues related to fluid pressure loss

Installation Notes and Tips

Installation of the Dorman M390320 master cylinder requires proper brake system bleeding to remove air and ensure optimal hydraulic function. Since mounting hardware is not included, retain or replace existing hardware as needed. Verify thread sizes (1/2-20 rearward outlet and 9/16-18 secondary outlet) for compatibility with your vehicle’s brake lines. It is recommended to inspect related brake components during installation for overall system integrity.

Quality Assurance and Warranty Information

Dorman manufactures this brake master cylinder to meet or exceed OEM specifications, using high-quality aluminum material for durability. While mounting hardware is not included, the product undergoes rigorous quality control to ensure reliable performance. Please consult Dorman’s warranty policy for specific coverage details related to the M390320 part.