Fitment questions?
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Product details
This black left-hand rear GP310 is a four-piston hydraulic caliper for the documented Dyna bottom-mount bracket configuration. Its billet body uses 3.50-inch mounting centers and a 3/8-24 inlet. Fitment is established by the correct Harley-Davidson rear bracket and rotor package, not the GP310 family name alone. Wilwood Engineering was founded by Bill Wood in 1977 and is based in Camarillo, California. The company makes disc brake systems and components for motorsport, street-performance and specialized uses, including calipers, brake rotors, master cylinders, valves, fittings and brake lines; each component must match the requirements of the complete brake system.
Technical Details
- Manufacturer part number: 120-7741-BK
- Caliper type: GP310 Motorcycle Rear
- Construction: Billet Aluminium
- Finish: Black 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: 9.00–11.50 inches
- Mounting style: Lug
- Mounting side: Left Hand
- Mounting centers: 3.50 inches
- Mounting-hole size: 0.39 inch
- Mount height: 1.55 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
Check the Dyna bottom-bracket reference and application listed in FL186 before choosing the left caliper. The bracket locates the caliper below the rotor and is supplied separately. Verify hydraulic line approach, pad alignment and clearance to the wheel, suspension and final drive, then confirm the motorcycle’s required fluid type.
PMB Performance has over 20 years of experience helping customers with brake and parts fitment. Share the installed component identification and relevant measurements when requesting assistance.
Brake-pad warning: Cancer and Reproductive Harm. www.P65Warnings.ca.gov. This warning applies to the brake pads.
