Wilwood Left-Valve Manual Master Cylinder Kit, Bare 7/8-inch Tandem with Pushrod

A captured threaded pushrod connects this bare 7/8-inch tandem master to a suitable manual pedal. The accompanying combination valve sits on the left bracket, joined to the master by formed stainless tubes. Based in Camarillo, California, Wilwood Engineering has designed and manufactured disc brake systems since Bill Wood founded the company in 1977. Its fittings, valves, calipers, brake lines, master cylinders and rotors are used across motorsport, street-performance and specialized applications. Matching a component means checking both its own specification and the braking assembly around it.

Technical Details

• Manufacturer part number: 261-13271
• 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: 12.26"
• Mounting centers: 3.22–3.40"
• Pushrod dimensions: 4.11" x 3/8-24
• 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

Check the pedal clevis for the 3/8-24 pushrod and confirm enough travel for the full 1.10-inch stroke. This general rod version is not the Mustang eyelet assembly; verify flange spacing and the left-side valve clearance separately.

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 has more than 20 years of experience matching brake components. Share the actual mounting, linkage and hydraulic arrangement when requesting fitment assistance.