Wilwood Black XRS4R Brake Caliper with Four 1.75-Inch Pistons, 1.10-Inch Rotor Width

Four 1.75-inch pistons give this black Wilwood XRS4R a larger effective area than smaller-bore versions of the family. It retains a nominal 1.10-inch rotor-width channel and forged radial-mount body, so mechanical fit and hydraulic suitability need separate checks. Bill Wood established Wilwood Engineering in 1977. Based in Camarillo, California, the company designs and manufactures disc brake systems for motorsport, street-performance and specialized use, including calipers, brake rotors, master cylinders, valves, fittings and brake lines.

Technical Details

• Manufacturer part number: 120-17206-BK. Type: Forged XRS4R Radial Mount caliper.
• Hydraulic inlet thread: 1/8-27 NPT. Match the fitting thread and sealing arrangement to the brake hose.
• Mounting: radial, 5.98-inch centers; orientation: universal. 0.39-inch holes; 1.45-inch mounting height.
• Piston arrangement: 4 stainless steel pistons; bore specification 1.75/1.75 inches. Effective piston area: 4.80 square inches.
• Rotor channel: 1.10-inch nominal width. Specified width limits: 1.00–1.10 inch; rotor outside diameter: 11.75–14.00 inches.
• Caliper body: forged aluminum; finish: Black Powder Coat.
• Piston dust boots: no.
• Brake pad shape: 10416. Choose pad dimensions and friction material for the brake system.
• Caliper component weight: approximately 5.0 lb.
• Component: one individual hydraulic brake caliper. Select the mating rotor, pads, mounting hardware and line connection to suit the complete brake assembly.

Fitment & Compatibility

The larger bores are not a substitute for evaluating master-cylinder volume and front-to-rear balance. Verify the 5.98-inch bracket, 1.00–1.10-inch rotor width and clearance around the wheel before selecting this unit.

For help matching this caliper, contact PMB Performance with the brake-package details and rotor measurements. Our team has more than 20 years of experience with brake parts and fitment.