Turn brake pedal force into hydraulic pressure for your brakes with the Dorman First Stop Brake Master Cylinder M39661, a new unit precision-engineered to replicate the design, function and performance of the original master cylinder. It fits many vehicles, among them the 1977-1985 Mercedes-Benz 300D, 1980-1985 Mercedes-Benz 300TD and 1984-1985 Mercedes-Benz 380SE, all engines. See the "Vehicles it fits" section for the full list. Built from new, high-quality materials, it is designed as a safe, durable replacement.
- Precise replacement: The cast iron cylinder housing is constructed to match the original part's casting material for similar performance.
- Durable design: Every rubber component is made from a high-quality EPDM compound that resists glycol-based brake fluid.
- 100% new: Made entirely of new materials for quality and safety.
- Strict specifications: Made to meet rigorous SAE International standards.
Specifications: The unit has 3 outlets. The rearward and secondary outlets use an M10 x 1.0 thread, and the primary outlet has a 1 mm thread pitch. The package contains the master cylinder only. The reservoir and sensor are not included, so transfer or replace them as directed by the service procedure. Mounting hardware is also not included; consult the vehicle service information for the correct fasteners and whether they may be reused. Country of origin: Italy.
Signs a master cylinder may need replacing: a soft or sinking brake pedal, fluid leaking at the master cylinder, or a steadily dropping fluid level. These symptoms can have other causes, so diagnose the brake system before you replace any parts. If the master cylinder is the cause, the M39661 replaces it.
Frequently Asked Questions
What does the Dorman M39661 brake master cylinder do?
It converts brake pedal force into hydraulic pressure and sends it through the brake lines to the wheels. The M39661 is a new unit with a cast iron housing.
Does the M39661 come with a reservoir?
No. The package contains the master cylinder only, without a reservoir, sensor or mounting hardware. Check the vehicle service information for how to transfer or replace those parts and which fasteners to use.
What are the outlet specifications?
It has 3 outlets. The rearward and secondary outlets use an M10 x 1.0 thread, and the primary outlet has a 1 mm thread pitch.
Which vehicles does this master cylinder fit?
It fits many Mercedes-Benz models, including the 1977-1985 Mercedes-Benz 300D, 1980-1985 Mercedes-Benz 300TD and 1984-1985 Mercedes-Benz 380SE. See the "Vehicles it fits" section for every application.
What are the rubber components made of?
All rubber components are made of a high-quality EPDM compound that resists glycol-based brake fluid. The unit is built to meet SAE International standards.
