The Wilwood 120-13405-SI is a Billet Narrow Dynalite radial-mount racing caliper with four pistons, two of them 1.75 inch in diameter, and a 4.80 square-inch total piston area. The manufacturer's Billet NDLR series uses a spacer-less body specifically for .38" and .810" width rotors, with a center bridge bolt that holds the top-loaded pads. Wilwood says the radial layout is a more rigid radial mount design than a tab-mount caliper, which is the main reason a sprint or midget builder would pay for it over a conventional lug-mount unit. Its pads are a 0.63" (16,0 mm) thick 7816 style type, and the manufacturer offers them in many different PolyMatrix compounds so you can tune brake torque and heat range for your class.
This caliper is aimed at sprint and midget inboard setups. The manufacturer states that radial mount bracket kits are used to install a radial mount caliper in place of a tab mount caliper, and that brackets are available for both Sprint and Midget Inboard and Dirt Late Model applications for various rotor diameters. Plan on sourcing the bracket with the caliper, because it is not included. Search terms buyers typically use for this part include "NDLR radial mount caliper 0.38 rotor," "Wilwood 1.75 piston inboard sprint caliper," and "120-13405-SI bracket."
Yes. Per the manufacturer, radial mount brackets are a separate purchase used to mount a radial caliper in place of a tab-mount caliper, and they are offered for Sprint and Midget inboard and Dirt Late Model applications.
The manufacturer notes that OEM rubber brake hoses generally cannot be adapted to Wilwood calipers. Its preferred method is steel adapter fittings at the caliper, and the inlet is a 1/8-27 NPT thread.
The manufacturer lists this model for 0.38 inch rotors with a maximum rotor diameter of 12.19 inches. Wider rotors require a different Narrow Dynalite part number.
Mounting this caliper is a bracket-and-alignment job rather than a simple pad swap, so plan for an intermediate skill level with a helper for centering. Per the manufacturer's Dynalite hub-kit assembly instructions, you should apply red Loctite 271 to the bracket bolt threads, then mount the caliper using the washers, bolts, and spacer supplied. Check that the rotor sits centered in the caliper window, and if it does not, the same instructions call for 0.032 inch shims between the bracket and caliper. Safety wire the caliper bolts once alignment is set. Replace the rubber hoses with steel lines and adapter fittings rather than reusing OEM hoses, and bleed the system afterward.
