Wilwood XRS4R Black Four-Piston Caliper, 5.98-Inch Radial Centers / 0.81-Inch Rotor Width

This black Wilwood XRS4R brings a four-piston layout to a brake system using a nominal 0.81-inch-wide rotor. Its 3.00-square-inch effective area and 5.98-inch radial centers identify the mechanical and hydraulic configuration more usefully than a broad vehicle label. Founded in 1977 by Bill Wood, Wilwood Engineering is based in Camarillo, California. It designs and manufactures disc braking systems for motorsport, street-performance and specialized applications, with a component range covering calipers, brake rotors, master cylinders, valves, fittings and brake lines.

Technical Details

• Manufacturer part number: 120-17203-BK. Type: Forged XRS4R Radial Mount caliper.
• Pad fit uses shape 10416. Match the pad to the rotor and intended operating conditions.
• Construction and surface: forged aluminum, finished in Black Powder Coat.
• Rotor dimensions: outside diameter 11.75–14.00 inches; nominal width 0.81 inch, with width limits of 0.75–0.84 inch.
• Hydraulic inlet thread: 1/8-27 NPT. Match the fitting thread and sealing arrangement to the brake hose.
• Bore sequence 1.38/1.38 inches across 4 pistons. Piston construction: stainless steel; specified effective area 3.00 square inches.
• Attachment geometry: radial mount with 5.98-inch centers; universal. 0.39-inch holes; 1.45-inch mounting height.
• Piston dust boots: no.
• Component: one individual hydraulic brake caliper. Select the mating rotor, pads, mounting hardware and line connection to suit the complete brake assembly.
• Caliper component weight: approximately 4.9 lb.

Fitment & Compatibility

Check how the bracket centers the caliper over the rotor and where the 10416 pads contact its friction face. The 1/8-27 NPT inlet also needs a fitting suited to the hose and sealing method.

With 20+ years of experience, PMB Performance can help assess the brake hardware. Provide the caliper number, rotor dimensions and bracket measurements when asking about compatibility.