Wilwood Left-Valve Tandem Master Cylinder Kit for Power Brakes, Bare 1-1/8-inch Bore

The larger 1-1/8-inch bore makes this bare High Volume Tandem kit primarily a power-brake choice. It includes a left-side combination valve, its bracket, stainless connecting tubes and fasteners around the integral-reservoir master. Wilwood Engineering serves motorsport, specialized and street-performance applications through disc brake system design and manufacturing. Bill Wood founded the company in 1977, and it is based in Camarillo, California. The range spans valves, rotors, fittings, calipers, brake lines and master cylinders; the installed braking assembly determines the appropriate combination of parts.

Technical Details

• Manufacturer part number: 261-13270
• Material: Aluminum
• Cylinder bore: 1-1/8"
• Pressure circuits: 2
• Stroke Length: 1.10 in
• Reservoir Type: Integral
• Fluid capacity: 8.0 / 4.8 oz
• Flange-to-end length: 8.15"
• Overall Length: 8.76"
• Mounting centers: 3.22–3.40"
• Finish: Bare
• Native pressure ports: 1/2-20 at both circuits; use the correct included outlet adapters and seal washers
• Circuit outlet adapters: Primary: 3/8-24 or 1/2-20 inverted flare; secondary: 3/8-24 or 9/16-18 inverted flare
• Hydraulic relationship: Equal pressure output from the two circuits before external proportioning; 2:1 primary/secondary volume relationship
• Service: Factory rebuild only; do not disassemble the tandem piston assembly
• Kit contents: Master cylinder, left-side combination proportioning valve and bracket, formed stainless connecting tubes and mounting hardware
• Combination-valve functions: Adjustable rear pressure, isolated front/rear circuits, front-line junction and hydraulic brake-light switch

Fitment & Compatibility

Verify the vacuum or hydraulic booster and actual piston engagement before ordering. The kit has no operating pushrod; the 3.22–3.40-inch flange and left valve envelope also need to match the vehicle's available space.

Manufacturer Documents

• Wilwood product specifications
• Wilwood DS985 instructions and specifications
• Wilwood FL331 instructions and specifications
• Wilwood FL162 instructions and specifications
• Wilwood DS487 instructions and specifications

PMB Performance brings over 20 years of brake-system experience to component selection. Send the installed cylinder, pedal and connection details if you need help checking this configuration.