This Dorman M630900 is a brand new (not remanufactured) Brake Master Cylinder designed as a direct replacement for specific BMW models (use the fitment tool to confirm!). The master cylinder is the heart of your brake system – it converts the pressure from your foot on the pedal into hydraulic pressure that activates the brakes at each wheel.
Dorman builds this part to match the original's casting material and performance. All the internal rubber components are made from high-quality EPDM compound, which is specifically resistant to modern glycol-based brake fluids. The entire unit is constructed from new materials and manufactured to meet rigorous SAE International standards for safety and reliability.
If your brake pedal feels soft, sinks to the floor, or you have a fluid leak near the firewall, your master cylinder might be failing. This Dorman part offers a quality, direct-fit solution to restore your braking system's integrity. As with all brake work, professional installation is highly recommended unless you have advanced mechanical skills.
