Wilwood 120-13839-BK Forged Dynalite Internal 4-Piston Caliper Black 1.38in 0.81

Vehicle Fitment

• Universal - Compatible with any application using 3.50" lug mount pattern and 0.81" wide rotors
• Left or right mount - symmetrical piston bore design allows mounting in either leading or trailing position on either side
• Compatible with short track, late model, modified, open wheel, road race, off-road, rally, and street performance applications
• Direct replacement for existing Forged Dynalite series calipers on 3.50" lug mount pattern

Fitment Notes

• 3.50" lug mount pattern - confirm your spindle or bracket uses this mounting pattern before purchase
• Designed for 0.81" wide rotors - confirm rotor thickness matches your application before installation
• Symmetrical 1.38"/1.38" piston bore allows mounting in left or right, leading or trailing position without modification
• Sold individually - two required for a complete axle
• Brake pads (7112 type) and mounting brackets not included - confirm compatible pad compound for your application
• Professional installation by a qualified brake technician is strongly recommended

Features

• Stress-flow forged aluminum body - next-generation enhancement of the venerable Forged Dynalite series, realigning internal grain structure within the caliper contour for superior strength
• FEA-generated radial transition design eliminates steps and shoulders between piston housings and caliper bridges, substantially increasing resistance to deflection and body separation under load
• Single split bridge, spacer-less construction - the stiffest and most visually refined design in the Dynalite family, starting at just 3.00 lbs.
• Internal fluid ports eliminate external crossover tubes, simplifying installation and removing a potential failure point
• Four symmetric 1.38"/1.38" pistons deliver fully balanced pad loading for even pad wear and consistent braking performance
• High-temperature square-faced O-ring seals provide positive sealing, controlled piston retraction, and long service life
• Black high-temp, brake fluid-resistant powder coat finish

Specifications

• Series: Forged Billet Dynalite Internal (FDLI)
• Piston Quantity: 4
• Piston Bore Sizes: 1.38" / 1.38" (symmetrical)
• Compatible Rotor Width: 0.81"
• Mounting: 3.50" Lug Mount
• Mount Orientation: Universal Left / Right
• Body Material: Stress-Flow Forged Aluminum
• Weight: Starting at 3.00 lbs.
• Pad Type: 7112
• Finish: Black Powder Coat (High-Temp, Brake Fluid Resistant)
• Parking Brake Provision: No
• Fittings Included: Yes
• Brake Pads Included: No
• Brackets Included: No
• Quantity: Sold Individually

Included Components

• 1x Wilwood Forged Billet Dynalite Internal Brake Caliper - Black (120-13839-BK)
• Brake line fittings

Product Description

The Wilwood 120-13839-BK is a Forged Billet Dynalite Internal (FDLI) four-piston lug mount brake caliper in black powder coat, representing the next generation evolution of Wilwood's legendary Forged Dynalite series. By applying stress-flow forging technology, the caliper body's internal grain structure is realigned within the caliper contour rather than interrupted as it would be in a machined billet design - producing the stiffest, most structurally efficient caliper in the Dynalite class, starting at just 3.00 lbs.

The FEA-generated radial transition design eliminates the steps and shoulders between piston housings and caliper bridges, substantially increasing resistance to deflection and body separation under braking load. Internal fluid ports replace external crossover tubes entirely for a cleaner, more reliable installation. The symmetric 1.38"/1.38" piston bore accommodates 0.81" wide rotors and allows the caliper to be mounted in any left or right, leading or trailing position without modification. The single split bridge, spacer-less construction further enhances both structural rigidity and visual appeal. Sold individually - two required per axle.