Convert brake-pedal force into the hydraulic pressure that operates the vehicle's brake circuits with the Dorman - First Stop Brake Master Cylinder (M630793). It drops in as a direct-fit replacement for the 1998 and 2002-2007 Isuzu NPR, 2002-2007 Isuzu NPR-HD, 2002-2007 Chevrolet W3500 and W4500 Tiltmaster, and 2002-2007 GMC W3500 and W4500 Forward (engine: All), precision-built to match the original master cylinder's design, function, and performance on the listed applications.
- 100% new: made entirely of new materials, not remanufactured.
- Cast iron housing: built to match the casting material of the original part for similar performance.
- EPDM rubber components: high-quality EPDM compound for resistance to glycol-based brake fluid.
- Made to meet rigorous SAE International standards.
Key specs: 1.25 in bore diameter, two outlets, single reservoir type, four mounting holes; rearward outlet size M10 x 1.0 and secondary outlet thread diameter 1/2-20. The package contains the master cylinder and a bleeder kit. A reservoir, cap, push rod, sensor, brake booster, and mounting hardware/bracket are not included — consult the vehicle service information for the correct fasteners and whether they may be reused. Country of origin: China.
Interchange: 100-3913 · 1003913 · 11-3971 · 113971 · 130.76010 · 355-47205 · 35547205 · 97315166 · 8973151660 · F140752 · MC140752
Manufacturer part number M630793.
This part cross-references / interchanges with the following part numbers:
Frequently Asked Questions
What does this brake master cylinder do?
It converts brake-pedal force into hydraulic pressure that operates the brake circuits. Signs it may need replacing include a sinking or spongy pedal or fluid leaks; diagnose the cause before replacing.
What vehicles does the M630793 fit?
It's listed for the 1998 and 2002-2007 Isuzu NPR, 2002-2007 Isuzu NPR-HD, 2002-2007 Chevrolet W3500/W4500 Tiltmaster, and 2002-2007 GMC W3500/W4500 Forward. See the Buyer's Guide tab.
What's included in the package?
The package contains the master cylinder and a bleeder kit. A reservoir, cap, push rod, sensor, brake booster, and mounting hardware or bracket are not included.
What are the bore and outlet specifications?
The bore diameter is 1.25 in with two outlets and four mounting holes. The rearward outlet size is M10 x 1.0 and the secondary outlet thread diameter is 1/2-20.
Is this master cylinder new or remanufactured?
It's 100% new, built entirely of new materials rather than remanufactured. The cast iron housing matches the original casting material, and the rubber components use EPDM for resistance to glycol-based brake fluid.