Wilwood Black One-Inch Mopar Compact Master with Four-Bolt Flange, Pushrod and Eyelet

An included Mopar-style eyelet and pushrod distinguish this one-inch master from the rodless four-bolt version. The black Compact Tandem housing contains the two fluid chambers and mounts to a verified rectangular Mopar firewall pattern. The disc brake systems Wilwood Engineering designs and manufactures include calipers, rotors, master cylinders, brake lines, valves and fittings. The company dates to Bill Wood's founding in 1977 and is based in Camarillo, California. Motorsport, specialized and street-performance applications all call for parts matched to the operating requirements of the full system.

Technical Details

• Manufacturer part number: 260-16854-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: 8.92 in
• 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
• 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: Included pushrod with Mopar eyelet; 3/8-24 adjustment thread. The drawing identifies a 2.00-inch eyelet, not the complete pushrod length.

Fitment & Compatibility

Match the pedal connection and 3.25-by-1.76-inch bolt centers to the actual installation. Wilwood reverses the primary and secondary outlet positions relative to the original Mopar master; reconnect by circuit function and the A/B labels. Preserve full piston travel, complete return and appropriate brake-line flare seats.

Manufacturer Documents

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

PMB Performance offers over 20 years of parts and brake-fitment experience. For a compatibility check, provide the existing assembly and the dimensions that govern the replacement.