Send hydraulic pressure to your brakes with every press of the pedal using the Dorman First Stop Brake Master Cylinder M104456, a new cast-iron unit that converts pedal effort into the pressure your braking system relies on. It fits many vehicles, among them the 1981-1985 Chevrolet Impala, 1983-1995 Chevrolet G20 and 1983-1995 GMC G2500, as a direct-fit replacement for the listed applications with all engines. See the "Vehicles it fits" section for the full list.
Dorman precision-engineers this master cylinder to mirror the original unit's design, function and performance. It is built from new, high-quality materials.
- Precise replacement: the cast-iron cylinder housing is made to match the casting material of the original part and is intended to provide similar performance.
- Durable design: every rubber component uses a high-quality EPDM compound for resistance to glycol-based brake fluid.
- 100% new: made entirely from new materials.
- Strict specifications: built to meet demanding SAE International standards.
Specifications: 30.04 mm bore diameter · 2 outlets · 1/2-20 in secondary outlet thread · reservoir included · mounting hardware and sensor not included. Country of origin: China.
A soft or sinking pedal, fluid seeping from the unit, or a falling reservoir level are signs a master cylinder may need replacing. These symptoms can have other causes, so diagnose the brake system first. Follow the vehicle service procedure for bleeding the new unit, and consult the service information for the correct fasteners and whether they may be reused.
Interchange: 174-837 · 783-36040 · 83-36040 · 100-2252 · M-82040 · 13-1863 · 10-1863 · 130.62040 · 131.62040 · 355-47049
174837 · 78336040 · 8336040 · 1002252 · M82040 · 131863 · 101863 · 13062040 · 13162040 · 35547049 · 18M160 · M900358 · 11863 · MC104456 · 14047683 · 25509416 · M1863 · NM1863 · MC39308 · F104456
This part cross-references / interchanges with the following part numbers:
174-837, 18M160, 783-36040, 83-36040, M900358, 100-2252, M-82040, 11863, 13-1863, 10-1863, 130.62040, 131.62040, MC104456, 355-47049, 14047683, 25509416, M1863, NM1863, MC39308, F104456
Frequently Asked Questions
Is this the right Impala master cylinder for a 1981-1985 Chevrolet Impala?
Yes. M104456 is listed as a direct-fit replacement for the 1981-1985 Chevrolet Impala with all engines. The "Vehicles it fits" section shows every listed vehicle.
What does a brake master cylinder do?
It converts force from the brake pedal into hydraulic pressure and sends it through its two outlets to the brake lines. This unit's rubber components use EPDM for resistance to glycol-based brake fluid.
What comes in the box?
One master cylinder with the reservoir included. Mounting hardware and a sensor are not included. Consult the vehicle service information for the correct fasteners.
What are signs a master cylinder may need replacing?
Common signs include a soft or sinking brake pedal, fluid leaking at the unit, or a dropping reservoir level. These can have other causes, so diagnose the brake system before replacing parts.
What are the key specifications of M104456?
It has a cast-iron housing, a 30.04 mm bore diameter, two outlets and a 1/2-20 inch secondary outlet thread. It is new and built to meet SAE International standards.
