Wilwood Left-Bracket Mustang Master Cylinder and Valve Kit, Black 7/8-inch Manual Tandem

The black tandem master in this kit uses a Mustang-style eyelet rather than a generic threaded clevis end. A left-side combination valve and preformed stainless tubes complete the master-to-valve connection for a custom manual-brake installation. A disc brake manufacturer based in Camarillo, California, Wilwood Engineering was founded by Bill Wood in 1977. It designs and manufactures calipers, rotors, brake lines, fittings, valves and master cylinders for street-performance, motorsport and specialized systems. The chosen service part must agree with the complete system's connections, dimensions and operating demands.

Technical Details

• Manufacturer part number: 261-13272-BK
• Material: Aluminum
• Cylinder bore: 7/8"
• 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: 13.65"
• Mounting centers: 3.22–3.40"
• Pushrod dimensions: 5.75"
• Finish: Black E-coat
• 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 early Ford Mustang pedal arrangement, including the corresponding master's 1964–1972 family scope and full return position. Check the 3.22–3.40-inch flange and available left-side space; a compatible mounting pattern does not validate altered linkage.

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

With more than 20 years of experience, PMB Performance can help compare the specified part with the assembly you are servicing. Include the existing part identification and relevant hydraulic dimensions.