AA Ignition Brake Master Cylinder for Cadillac/Chevrolet/GMC 1999–2002 – Direct-Fit, Precision-Bored Replacement

AA Ignition Brake Master Cylinder: a direct-fit replacement that restores hydraulic brake pressure for compatible Cadillac, Chevrolet and GMC models.

If your brake pedal feels low, sinks, or your vehicle is showing signs of a master cylinder leak, this AA Ignition brake master cylinder is engineered to be a straightforward swap for many GM trucks and SUVs from the 1999–2002 era. It cross-references common OEM and aftermarket part numbers such as M630031, 18040252 and 18060789 so you can match your original part number and confirm fitment before purchase. Built with a precision-bored cylinder and improved sealing, the unit is designed to meet or exceed factory specifications without requiring modifications.

How will this master cylinder affect pedal feel and braking response?

Replacing a worn master cylinder typically returns a firmer pedal and more consistent brake pressure. This unit restores the hydraulic pressure that actuates the brake system, addressing symptoms like a spongy or sinking pedal caused by internal seal wear or fluid leakage.

• Precision-bored cylinder for uniform bore surface and predictable pressure.
• New internal seals to eliminate internal bypass and loss of pressure.
• Direct-fit ports and mounting for a plug-and-play installation.

Which vehicles and part numbers does this cylinder fit?

This master cylinder is compatible with a range of Cadillac, Chevrolet and GMC models from the early 2000s; always verify with your vehicle’s VIN or existing part number. It replaces several common numbers used by OEMs and aftermarket suppliers to simplify identification.

• Fits Cadillac Escalade and Escalade EXT (2002) and multiple Chevrolet models including Avalanche 1500, Blazer, Silverado 1500/1500 HD, Suburban and Tahoe (1999–2002 ranges).
• Cross-references: M630031, M630031AA, 18040252, 18060789, 19209249.
• Check the compatibility chart and match the part number on your old master cylinder before ordering.

What should I know about installation and maintenance?

The part is designed for a straightforward swap with factory-style mounting and port locations, but safe, proper installation requires attention to bleeding and fluid cleanliness. For best results, bench-bleed the master cylinder before connecting brake lines and flush the brake fluid in the system per manufacturer guidelines.

• Direct-fit design means no modification of mounting points or lines is typically required.
• Bench-bleeding removes trapped air inside the cylinder prior to vehicle installation.
• Replace brake fluid and bleed the entire system after installation for consistent performance.

What warranty and quality assurances are included?

While this is not an OEM-branded component, AA Ignition manufactures the unit to meet or surpass factory tolerances and backs it with a lifetime warranty. If the master cylinder fails due to manufacturing defects, AA Ignition will replace it, helping avoid dealer-level repair costs.

• Engineered to factory-style specifications with improved sealing components.
• Lifetime warranty from AA Ignition for replacement on qualified failures.
• Recommended to verify part number compatibility before purchase to ensure warranty coverage applies.

Who is this for: This master cylinder is intended for owners and mechanics working on late-1990s to early-2000s Cadillac, Chevrolet or GMC trucks and SUVs who need a reliable, direct-fit replacement for worn or leaking master cylinders. If you value a plug-and-play swap that restores braking pressure and want a part backed by a lifetime warranty, this unit offers a cost-effective alternative to dealer-sourced assemblies. Always verify vehicle fitment and follow safe installation and bleeding procedures.