Turn each press of the brake pedal into hydraulic pressure at the wheels with this Dorman brake master cylinder from the First Stop line, part number M631012. It is a direct-fit replacement for the 2012-2018 Ram 2500 and 2012-2018 Ram 3500. See the Buyer's Guide tab for engine and trim details.
The master cylinder is the hydraulic heart of the braking system. It converts the force from your foot into fluid pressure that travels through the brake lines to each wheel. Dorman designed this unit to match the original master cylinder in design, function and performance, and built it from new, high-quality materials for a durable replacement.
- Precise replacement: The cylinder housing is made to match the casting material of the original part, for similar performance.
- Durable design: All rubber components use a high-quality EPDM compound that resists glycol-based brake fluid.
- 100% new: The unit is made entirely from new materials.
- Strict specifications: It is built to meet rigorous SAE International standards.
Signs the master cylinder may need replacing include a soft or sinking brake pedal, brake fluid leaking at the cylinder, or a lit brake warning light. Other brake faults can cause the same symptoms, so diagnose the cause before replacing. If a worn master cylinder is the source, this unit replaces it.
Interchange: 100-4075 · 130.67051 · 355-40087
68144664AA · NM4275 · MC391465 · 1004075 · 13067051 · 35540087
This part cross-references / interchanges with the following part numbers:
100-4075, 130.67051, 68144664AA, 355-40087, NM4275, MC391465
