Wilwood Black Four-Piston XRS4R, 1.10-Inch Rotor Channel and Forged Radial-Mount Body

This black Wilwood XRS4R uses a forged housing to locate four equal 1.38-inch pistons over a nominal 1.10-inch-wide rotor. The caliper's internal fluid ports avoid an external crossover tube, but its suitability still depends on the chosen bracket and brake hydraulics. 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: 120-17205-BK. Type: Forged XRS4R Radial Mount caliper.
• Compatible pad profile 10416; confirm thickness and compound for the installation.
• Black Powder Coat finish on a forged aluminum body.
• Nominal rotor width 1.10 inch; compatible width range 1.00–1.10 inch. Rotor diameter specification: 11.75–14.00 inches.
• Hydraulic inlet thread: 1/8-27 NPT. Match the fitting thread and sealing arrangement to the brake hose.
• 4-piston hydraulic layout with 1.38/1.38-inch bores and 3.00 sq in of effective area; piston type: stainless steel.
• 5.98-inch-center radial attachment, universal orientation. 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 5.1 lb.

Fitment & Compatibility

Use an 11.75–14.00-inch rotor only after checking its offset and pad contact area. Match the 10416 pad outline and verify the wheel barrel clears the housing through the installation's operating positions.

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.