Fitment questions?
Call (855) 786-7101 or text (801) 304-3141.
Real people. Real answers.
Product details
The red left-hand GP310 is the earlier front motorcycle version with 3.44-inch lug spacing. It provides four-piston hydraulic braking for the supported 1984–1999 Harley-Davidson front arrangement. The selected piston area is 2.46 square inches, and the caliper uses stainless pistons without external dust boots. Founded in 1977 by Bill Wood, Wilwood Engineering is based in Camarillo, California. Its disc brake systems and components serve motorsport, street-performance and specialized applications. Calipers, brake rotors, master cylinders, valves, fittings and brake lines are among its products, selected according to the complete brake system’s requirements.
Technical Details
- Manufacturer part number: 120-7737-RD
- Caliper type: GP310 Motorcycle Front (1984-1999)
- Construction: Billet Aluminium
- Finish: Red Powder Coat
- Piston bores: 1.25 / 1.25 inches
- Piston type: Stainless
- Piston count: 4
- Published piston area: 2.46 square inches
- Dust boots: No
- Nominal rotor width: 0.25 inch
- Rotor thickness limits: 0.18–0.25 inches
- Rotor diameter limits: 11.00–11.50 inches
- Mounting style: Lug
- Mounting side: Left Hand
- Mounting centers: 3.44 inches
- Mount height: 2.33 inch
- Hydraulic inlet thread: 3/8-24
- Required pad shape: 6208
- Published pad area: 3.65 square inches
- Published pad volume: 0.63 cubic inches
- Manufacturer-listed component weight: 2.1 lb
- Supplied brake components: Individual GP310 caliper with brake pads
Fitment & Compatibility
Confirm the exact motorcycle and fork mount, applying Wilwood’s Springer and four-speed FL exclusions. Verify rotor width, diameter and pad position with the front assembly. On a modified bike, also check the hose fitting, wheel-spoke envelope and the complete system’s fluid requirements rather than relying on the original model year. Wilwood also specifically includes the 1983 Harley-Davidson XR1000 front application; verify the same fork, rotor and mounting requirements.
PMB Performance brings over 20 years of brake and parts experience to selection questions. Send the existing caliper reference and brake-package details for help checking compatibility.
Brake-pad warning: Cancer and Reproductive Harm. www.P65Warnings.ca.gov. This warning applies to the brake pads.
