ACDelco 18M794B Professional Brake Master Cylinder Assembly

The ACDelco 18M794B is a Professional-grade brake master cylinder assembly engineered as a premium replacement for the hydraulic braking system. As the heart of the brake system, the master cylinder converts mechanical force from the brake pedal into hydraulic pressure, distributing fluid through the brake lines to activate the calipers and bring the vehicle to a controlled stop.

Key Features:

• SAE J1153 & J1154 Compliant — Meets established brake performance standards for reliability and safety
• Pressure Tested — Each unit is pressure tested prior to packaging to ensure safe, confident braking performance
• Cast Iron & Aluminum Construction — Dual-material body minimizes stress on the brake booster mounting
• Precision Geometry — Tight tolerances ensure the body and plastic reservoir mate correctly for a leak-free fit
• Piston Assembly & Return Spring — Helps prevent brake drag to reduce premature brake pad wear
• EPDM & SBR Rubber Components — Superior resistance to heat, corrosion, and fluid leakage
• Bleeder Hoses Included — Ready to bench bleed straight out of the box; no extra assembly required
• 1.125" Bore Size — Primary outlet thread: 0.562"; Secondary outlet thread: 0.500"
• 2-Port, 2-Mounting-Hole Design — Direct bolt-on fitment; no programming required

Specifications:

• Master Cylinder Material: Aluminum
• Bore Size: 1.125 in
• Primary Outlet Thread Diameter: 0.562 in (14.275 mm)
• Secondary Outlet Thread Diameter: 0.500 in (12.700 mm)
• Port Quantity: 2
• Mounting Hole Count: 2
• Brake Booster Included: No
• Pushrod Included: No
• Bleeder Hoses Included: Yes
• Master Cylinder Cap Included: Yes
• OE Cross-Reference Numbers: 18029955, 18060791, 18039263

The ACDelco 18M794B is backed by ACDelco's Professional line quality standards — the same engineering and approval process used for OE General Motors components — making it a dependable, direct-fit replacement for a worry-free brake system restoration.