Wilwood Black One-Inch Mopar Four-Bolt Master and Right Valve Kit, No Pushrod

This Mopar four-bolt package combines a black one-inch master with a right-side valve bracket and no manual pushrod. It must be selected around the actual booster or operating linkage and the complete brake configuration. Established in 1977 by Bill Wood, Wilwood Engineering designs and manufactures disc brake systems from its base in Camarillo, California. Calipers, fittings, rotors, valves, master cylinders and brake lines serve its motorsport, street-performance and specialized applications. The full assembly, including its mating connections and operating requirements, governs the correct part selection.

Technical Details

• Manufacturer part number: 261-17798-BK
• Material: Aluminum
• Cylinder bore: 1.00"
• 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, right-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

Check the booster-to-piston clearance and four-bolt mounting flange. Confirm full travel, right bracket clearance and the correct flare adapters for the brake lines.

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.