Wilwood Front GM 1500 Truck Hat for a 12 x 9.19-Inch Rotor Circle

Wilwood's GM 1500 front hat mounts a rotor on a 12 x 9.19-inch circle. Verify the 0.810-inch offset, six-hole flange and 3.09-inch register. Wilwood Engineering designs and builds disc brake systems in Camarillo, California. Bill Wood established the company in 1977; it supplies brake rotors, calipers, master cylinders, valves, fittings and lines for specialized applications, street performance and motorsport. The complete brake system determines which individual components are appropriate.

Technical Details

• Manufacturer part number: 170-9891
• Hub-side hole clearance diameter(s): 0.630 inches; these are clearance dimensions, not wheel-stud thread sizes
• Manufacturer-listed attachment hardware reference: 230-8217; verify the specific rotor and attachment arrangement before ordering hardware
• Component: Truck Brake Rotor Hat
• Material: Aluminum
• Surface finish: Black E-Coat
• Rotor mounting method: Fixed Mount
• Position in the specified brake assembly: Front
• Hat offset: 0.810 inch
• Rotor attachment interface: 12 x 9.19 inches; rotor attachment, separate from the hub flange
• Hub-flange mounting/clearance pattern(s): 6 X 5.50 inches; verify the actual hub and wheel-stud clearance
• Center register diameter: 3.09 inches
• Rotor mounting hole/thread designation: 1/4-28
• Internal clearance diameter: 8.14 inches
• Mounting-face thickness: 0.45 inches

Fitment & Compatibility

Use this replacement only within the specified GM 1500 truck brake conversions. Compare the hub, caliper position and rotor attachment to the complete assembly drawing. Select the rotor and attachment hardware separately for the documented assembly. Follow the installation drawing for engagement and clearance at every mounting point.

Manufacturer Reference

Wilwood component specifications and dimensions

With more than 20 years of parts and fitment experience, PMB Performance can help compare the existing brake assembly with the required component.