Wilwood Left-Valve Classic Mustang Master Cylinder Kit, Chrome 7/8-inch Tandem with Eyelet

A chrome powder-coated 7/8-inch master anchors this Mustang manual-brake kit. The supplied eyelet linkage is combined with a black left-hand valve assembly, allowing the cylinder and proportioning hardware to be installed as a matched package. Bill Wood established Wilwood Engineering in 1977. From Camarillo, California, Wilwood designs and manufactures disc brake systems and a component range covering master cylinders, rotors, calipers, fittings, valves and brake lines. Across its motorsport, specialized and street-performance applications, the correct choice depends on the complete brake system rather than one dimension alone.

Technical Details

• Manufacturer part number: 261-13272-P
• 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: Chrome powder 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

Confirm the classic Ford Mustang manual pedal geometry; the bare-master family lists 1964–1972. Allow full stroke and unimpeded return, and size the bore for the installed brakes rather than treating the vehicle name as approval of every conversion.

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

For help choosing the correct service or conversion component, contact PMB Performance with the existing brake-system details. Our team has over 20 years of experience working through parts and fitment requirements.