Wilwood Yellow FNSL4R Caliper, 1.38/1.38-Inch Piston Bores

Wilwood supplies this FNSL4R brake caliper with a yellow finish. Its 5.98-inch mounting span and 0.95-inch-wide rotor configuration are key checks when selecting a single caliper for an existing system. Based in Camarillo, California, Wilwood Engineering has its origins in the company Bill Wood founded in 1977. Its designs and manufactured disc brake products cover calipers and rotors alongside master cylinders, valves, fittings and lines. Motorsport, street-performance and specialized installations each require components selected for the complete system. The Forged Narrow Superlite 4R is a four-piston radial caliper using the 7416 pad outline. Its nominal 0.95-inch-wide rotor configuration must be matched to the mounting height and hydraulic balance of the installation. Wheel clearance is determined by the entire caliper-and-bracket envelope.

Technical Details

• Manufacturer part number: 120-16683-Y
• Component: Forged Narrow Superlite 4 Radial Mount; one individual caliper
• Placement: Universal mounting orientation; verify axle position
• Construction and finish: Forged aluminum; Yellow Powder Coat
• Pistons: 4; stainless steel; bore dimensions 1.38/1.38 inches
• Hydraulic piston area: 3.00 square inches
• Dust boots: No
• Brake pad shape: 7416; shape number does not specify a friction compound
• Mounting interface: Radial; mounting centers 5.98 inches
• Mounting-hole diameter: 0.39 inches
• Mount height: 1.45 inches
• Hydraulic inlet thread: 1/8-27 NPT
• Nominal rotor width: 0.95 inches
• Rotor width range: 0.89–0.99 inches
• Rotor diameter range: 11.42–14.00 inches
• Caliper weight reference: 5.0 lb

Fitment & Compatibility

Choose this component around the existing rotor and bracket, including the 0.95-inch nominal rotor width and 5.98-inch mounting span. Axle placement is determined by the engineered brake package, not by a generic caliper designation. Compare pad support, caliper offset and piston volume with the brake being replaced. Wheel size alone cannot confirm spoke or barrel clearance.

Wilwood caliper specifications · Wilwood technical reference

Share the vehicle and the brake system actually installed with PMB Performance before ordering if the configuration is uncertain. We draw on over 20 years of parts and fitment experience when comparing the rotor, mount and caliper.