Master Cylinder .625in Bore GS Compact

The Master Cylinder .625in Bore GS Compact by Wilwood is an essential hydraulic component designed for builders and enthusiasts who demand precision brake system performance in tight engine bay configurations. This compact master cylinder serves dual-circuit braking applications where space constraints prohibit full-size units, making it ideal for custom street rods, vintage restorations, and purpose-built track vehicles. Wilwood's engineering delivers reliable pressure modulation without sacrificing stopping power, whether you're running a weekend cruiser or a competition-focused build.

The .625-inch bore diameter is engineered to balance pedal feel and hydraulic pressure delivery across modern brake caliper designs. This compact GS configuration integrates a proportioning valve function within the housing, simplifying plumbing and eliminating separate bias adjusters on many applications. Cast ductile iron construction paired with Wilwood's precision-honed cylinder walls ensures consistent performance across repeated brake cycles while maintaining minimal wear characteristics. The compact footprint—measuring just 6 by 2.3 inches—fits where conventional cylinders simply won't, without compromising the structural integrity required for high-pressure hydraulic systems.

Mechanics and fabricators benefit most from this cylinder when retrofitting older vehicles with modern four-wheel disc brakes or when packaging brake systems in limited-clearance engine compartments. The GS Compact pairs seamlessly with Wilwood disc brake kits and proportioning valves, making system integration straightforward for both experienced builders and first-time brake system installers. Weighing just 1.08 pounds, it reduces unsprung weight while maintaining the reliability demanded by street-driven and track-focused vehicles alike.