Wilwood Left-Side Proportioning Valve and Black Tandem Master Cylinder Kit, 1-inch Bore

Black E-coat finishes both the one-inch master body and its left-hand valve bracket. The package adds a combination proportioning valve to the integral-reservoir tandem cylinder, giving a custom brake installation an accessible rear-pressure adjustment. Wilwood Engineering's disc brake systems bring together calipers, rotors, valves, master cylinders, fittings and brake lines. Founded by Bill Wood in 1977 and based in Camarillo, California, the company designs and manufactures products for motorsport, street-performance and specialized applications. The installed system determines which individual component is appropriate.

Technical Details

• Manufacturer part number: 261-13269-BK
• Material: Aluminum
• Cylinder bore: 1.00"
• 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: 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

The master can serve a correctly sized manual or power-assisted system, but does not include its operating pushrod. Verify the booster or pedal connection and keep clearance around the valve knob, line fittings and reservoir lid.

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

The component must suit the completed installation. PMB Performance draws on over 20 years of experience to help you check the part identification, mating connections and required operating dimensions.