Dorman M39405 Brake Master Cylinder

Reliable Brake Master Cylinder for BMW 320i and 325e

The Dorman M39405 brake master cylinder is engineered to meet the hydraulic braking needs of BMW 320i and 325e models. Designed with precision, this cast iron master cylinder ensures consistent brake fluid pressure for safe and effective braking performance.

• Master cylinder bore diameter: 0.813 inches for accurate hydraulic control
• Constructed from durable cast iron material for long-lasting strength
• Includes four outlets with a rearward outlet size of M10 x 1.0 and a thread pitch of 1.0
• Secondary outlet thread diameter measures 10 mm
• Package contains the master cylinder only; mounting hardware and reservoir are not included
• No sensor included, designed for direct replacement applications

Technical Details and Compatibility

The Dorman M39405 brake master cylinder is specifically compatible with BMW 320i and 325e vehicles, providing a direct fit replacement for the original component. Its 0.813-inch bore diameter is calibrated to maintain proper hydraulic pressure within the brake system. Manufactured from cast iron, this master cylinder offers durability and resistance to wear under demanding braking conditions. The unit features four outlets, including a rearward outlet sized M10 x 1.0 with a 1.0 thread pitch, ensuring secure connections to brake lines. Note that this product does not include a reservoir or mounting hardware, so these components must be sourced separately if needed.

Common Applications and Problem Resolution

• Restores brake fluid pressure in BMW 320i and 325e hydraulic systems
• Replaces worn or leaking master cylinders causing brake pedal issues
• Addresses brake fluid leaks from damaged or corroded master cylinders
• Improves brake responsiveness and pedal feel in affected vehicles
• Suitable for maintenance or repair of brake hydraulics on compatible BMW models

Installation Notes and Tips

Installation of the Dorman M39405 brake master cylinder requires proper brake system bleeding to remove air and ensure optimal hydraulic function. Since mounting hardware and reservoir are not included, verify the condition of existing components before installation. Use appropriate tools to secure the master cylinder outlets with the specified M10 x 1.0 thread pitch fittings. It is recommended to consult the vehicle’s service manual for torque specifications and detailed installation procedures to maintain safety and performance standards.

Quality Assurance and Warranty Information

Dorman manufactures the M39405 brake master cylinder to meet industry standards for brake hydraulics. The cast iron construction provides reliable durability under normal operating conditions. While specific warranty details are not provided here, Dorman products typically come with a limited warranty covering defects in materials and workmanship. For exact warranty terms, refer to the product documentation or contact the manufacturer directly.