Turn pedal effort into hydraulic braking pressure with the Dorman - First Stop Brake Master Cylinder M630940 — the cylinder itself, reservoir included, rather than a Dorman master cylinder bleeder kit. It is a direct-fit replacement for the 2015-2019 Hyundai Sonata and the 2016-2019 Kia Optima (All engines), with one per vehicle.
Dorman precision-engineered this unit to mirror the original master cylinder's design, function and performance on the listed applications, using new, high-quality materials for a safe, durable replacement.
- Precise replacement: the cylinder housing is built to match the casting material of the original part for similar performance.
- Durable design: every rubber component uses a high-quality EPDM compound that resists glycol-based brake fluid.
- 100% new: made entirely of new materials for quality and safety.
- Strict specifications: built to meet rigorous SAE International standards.
Specifications: cast-iron housing; 0.9375-inch bore diameter; two outlets (rearward outlet size M12 x 1.0, secondary outlet thread M12 x 1.0, primary outlet thread pitch 1 mm); single reservoir included; sensor included. Mounting hardware is not included. Country of origin: China.
Replacing a master cylinder typically requires bleeding the brake system. Follow the vehicle service information for the correct procedure and fasteners.
Interchange: 100-4130 · 130.51073 · 355-03067
58510C1500 · MC391510 · 1004130 · 13051073 · 35503067
This part cross-references / interchanges with the following part numbers:
100-4130, 130.51073, 355-03067, 58510C1500, MC391510
Frequently Asked Questions
What does a Dorman brake master cylinder do?
It converts force at the brake pedal into hydraulic pressure and sends brake fluid through its two outlets to the brake lines. This unit has a 0.9375-inch bore.
Which vehicles does M630940 fit?
It fits the 2015-2019 Hyundai Sonata and the 2016-2019 Kia Optima (All engines), with one master cylinder per vehicle. Check the "Vehicles it fits" section for your exact vehicle.
Is the reservoir included?
Yes. It comes with a single reservoir, and the sensor is included as well. Mounting hardware is not included.
What are signs a master cylinder may need replacing?
Common signs include a soft or sinking brake pedal, fluid leaking around the cylinder or reservoir, and a lit brake warning light. Diagnose the brake system first, because other parts can cause these symptoms.
What is this master cylinder made of?
The housing is cast iron, and all rubber components use a high-quality EPDM compound that resists glycol-based brake fluid. It is made entirely of new materials and built to meet SAE International standards.
