Wilwood Mopar Four-Bolt Compact Master Kit, Black 1-1/8-Inch Bore, Left Valve and No Pushrod

A black 1-1/8-inch tandem master with a Mopar four-bolt mounting flange is paired with a left-mounted combination valve. The booster or linkage must suit the master input without a supplied rod. Wilwood Engineering began in 1977 under founder Bill Wood and is based in Camarillo, California. The company designs and builds disc brake systems for motorsport, street-performance and specialized applications, with a range extending through calipers, rotors, valves, brake lines, fittings and master cylinders. Individual parts must be compatible with the system in which they operate.

Technical Details

• Manufacturer part number: 261-16798-BK
• Material: Aluminum
• Cylinder bore: 1-1/8"
• Pressure circuits: 2
• Stroke Length: 1.10 in
• Reservoir Type: Integral
• Fluid capacity: 7.8 / 4.7 oz
• Overall Length: 7.16"
• Mounting centers: 3.25 × 1.76"
• 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 9/16-20 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
• Flange-to-end references: Exact product page: 6.55 inches; DS-1520 dimensional drawing: 6.70 inches. Confirm the available installation envelope.
• Circuit routing: Primary outlet A feeds the axle with greater total effective caliper piston area, normally the front; secondary B feeds the lesser-area axle, normally the rear. Outlet locations are reversed from the original Mopar master cylinder; follow DS-1520.
• Linkage: Pushrod not included; match the existing or separately supplied actuation interface

Fitment & Compatibility

Confirm the Mopar mounting and the intended booster interface. Check hydraulic bore selection, full travel and the outlet fittings' actual flare seats.

Manufacturer Documents

• Wilwood product specifications
• Wilwood DS1520 instructions and specifications
• Wilwood FL162 instructions and specifications
• Wilwood DS1178 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.