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Dorman - First Stop Brake Master Cylinder P/N:M21698
$218.99
Turn brake-pedal pressure into the hydraulic force that works your brakes with the Dorman - First Stop Brake Master Cylinder M21698. It's a direct-fit replacement for the 1955-1959 GMC 300 [All] and 1955-1959 GMC 370 [All], precision-built to match the design, function, and performance of the original master cylinder on these applications. The cast iron housing is made to match the casting material of the original part for similar performance, and it ships 100% new — not remanufactured.
- Cast iron construction: housing matches the original's casting material for consistent, durable performance.
- EPDM rubber components: all rubber parts use a high-quality EPDM compound for resistance to glycol-based brake fluid.
- Built to spec: 1.25 in bore, a single outlet with a 7/16-24 rearward outlet size, and an included reservoir; made to meet rigorous SAE International standards.
- What's included: master cylinder with reservoir. Sensor not included and mounting hardware not included.
Signs the original master cylinder may need replacing include a sinking or spongy brake pedal, fluid loss, or a loss of hydraulic pressure. Country of origin: Taiwan.
Interchange: 83-52004 · 100-2764 · M-90004 · 13-21698 · 10-21698 · 130.80004 · 355-71008
8352004 · 1002764 · M90004 · 1321698 · 1021698 · 13080004 · 35571008 · M900037 · 11204 · MC509410 · 2621177 · 5454494 · 5459980 · MC21698 · F21698 · F36666 · MC36666
This part cross-references / interchanges with the following part numbers:
83-52004, M900037, 100-2764, M-90004, 11204, 13-21698, 10-21698, 130.80004, MC509410, 355-71008, 2621177, 5454494, 5459980, MC21698, F21698, F36666, MC36666
Frequently Asked Questions
What does the brake master cylinder do?
It converts the force from your brake pedal into hydraulic pressure that actuates the brakes. This M21698 is a direct-fit replacement for the listed applications.
Which vehicles does the M21698 fit?
It fits the 1955-1959 GMC 300 [All] and 1955-1959 GMC 370 [All]. Check the Buyer's Guide tab to confirm fitment for your vehicle.
Is the reservoir included?
Yes, the reservoir is included. A sensor is not included, and mounting hardware is not included.
What are the key specs?
It has a 1.25 in bore, a single outlet with a 7/16-24 rearward outlet size, a cast iron housing, and EPDM rubber components that resist glycol-based brake fluid.
Is this a remanufactured unit?
No. It is made entirely of new materials, not remanufactured, and is made to meet rigorous SAE International standards.
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Dorman - First Stop Brake Master Cylinder P/N:M21698
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