Wilwood Anodized Aero4 Radial Brake Caliper, 1.38-Inch Pistons / 1.10-Inch Rotor Width

The anodized Wilwood Aero4 uses four equal stainless pistons in a forged aluminum radial-mount housing. This 1.38-inch-bore version has 3.00 square inches of effective area and a nominal 1.10-inch rotor-width channel, with internal fluid passages between the piston banks. Wilwood Engineering was founded by Bill Wood in 1977 and is based in Camarillo, California. The company designs and manufactures disc brake systems and components, including calipers, brake rotors, master cylinders, valves, fittings and brake lines for motorsport, street-performance and specialized applications.

Technical Details

• Manufacturer part number: 120-17724. Type: Aero4 Radial Mount caliper.
• Piston arrangement: 4 stainless steel pistons; bore specification 1.38/1.38 inches. Effective piston area: 3.00 square inches.
• Hydraulic inlet thread: 1/8-27 NPT. Match the fitting thread and sealing arrangement to the brake hose.
• Mounting: radial, 7.09-inch centers; orientation: universal. 0.45-inch holes; 2.09-inch mounting height.
• Caliper body: forged aluminum; finish: Type III Anodize.
• Rotor channel: 1.10-inch nominal width. Specified width limits: 1.00–1.10 inch; rotor outside diameter: 12.19–15.00 inches.
• Caliper component weight: approximately 6.9 lb.
• Brake pad shape: 6617. Choose pad dimensions and friction material for the brake system.
• 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.

Fitment & Compatibility

Match the 7.09-inch radial centers and mounting height to the actual bracket. Check rotor offset and the 12.19–15.00-inch diameter envelope while ensuring the 6617 pads follow the intended friction ring.

PMB Performance has over 20 years of brake-component experience. Send the existing caliper identification, rotor measurements and mounting details for help comparing this configuration.