Dorman Brake Master Cylinder M630031 for GM Trucks/SUVs (1999–2002) — Direct-Fit, 100% New with EPDM Seals

The Dorman M630031 Brake Master Cylinder is a 100% new, direct-fit replacement engineered to restore original braking function on select Chevrolet, GMC and Cadillac trucks and SUVs from 1999–2002.

This master cylinder is built to match the casting, fit and function of the factory part while using new materials throughout for reliable, long-lasting performance. Manufactured to meet SAE standards, the unit includes high-quality EPDM rubber components formulated for resistance to glycol-based brake fluids. Before purchase, verify your exact trim and year using the vehicle garage tool to confirm fitment.

Which vehicles does this Dorman master cylinder fit?

The M630031 is designed for specific GM full-size trucks and SUVs across model years primarily between 1999 and 2002. Compatibility covers multiple Chevrolet and GMC models plus Cadillac Escalade variants—always check the Confirmed Fit bar and any fitment notes in the garage tool for precise match details.

• Chevrolet: Avalanche 1500 (2002), Blazer (2000–2002), Silverado 1500/1500 HD (1999–2002), Suburban 1500 (2000–2002), Tahoe (2000–2002)
• GMC: Sierra 1500/1500 HD (1999–2002), Yukon/Yukon XL 1500 & 2500 (2000–2002)
• Cadillac: Escalade and Escalade EXT (2002)

How does this master cylinder match the original equipment?

Dorman engineered this unit to replicate the original casting material and dimensions so it integrates with existing brake lines, booster and mounting points. The mechanical design aims to mirror OE performance characteristics for pedal feel and hydraulic operation under typical driving conditions.

• Housing cast to mimic original material and shape for proper fit
• Mounting bosses and ports located to match factory connections
• New internal components for predictable hydraulic response

What materials and standards are used in the M630031?

The unit is built entirely from new materials rather than being remanufactured, with rubber seals made from EPDM to resist breakdown from glycol-based brake fluids. Production follows strict SAE specifications to ensure durability and compatibility with typical braking systems.

• 100% new construction—no remanufactured parts
• EPDM rubber components for fluid resistance and longevity
• Manufactured to meet SAE International standards for quality

What should I check before installing this master cylinder?

Confirm fitment by entering your vehicle trim in the garage tool and reviewing any fitment notes. Inspect the brake booster, lines and fittings for wear or leaks; replacing these related items as needed ensures the new master cylinder operates without issues after installation.

• Use the garage tool and Confirmed Fit bar to verify compatibility
• Check brake booster, lines, hose ends and fittings for damage
• Bleed the brake system completely after installation to remove air

Who is this for: The Dorman M630031 is intended for owners and independent technicians working on late‑1990s to early‑2000s Chevrolet, GMC and Cadillac full‑size trucks and SUVs who need a dependable, brand-new master cylinder that duplicates original fit and function. It’s well suited for restorations, routine brake system repairs, or when an aging or leaking master cylinder is causing reduced pedal feel or fluid loss. Remember to verify fitment for your exact model and year before ordering.

Features:

• Precise replacement - cylinder housing is constructed to match the casting material of the original part and ensure similar performance
• Durable design - all rubber components are made of quality EPDM compound for resistance to glycol-based brake fluid
• 100% new - made entirely of new materials, not remanufactured, to ensure highest quality and safety
• Strict specifications - made to meet rigorous SAE International standards
• Ensure fit - Input your vehicle into the garage tool and check Confirmed Fit bar at the top of the page. If there is an “i” in a blue circle, additional verification is needed. Please hover over the "i" to verify fitment notes match your vehicle.