The Wilwood 120-13840 is a four-piston forged aluminum caliper built on the brand's Forged Dynalite line. The process of stress-flow forging re-aligns the metal's grain structure within the contour of the caliper body. The FEA-generated radial transition design eliminates steps and shoulders between the piston housing and the caliper bridges, and that radius substantially increases resistance to deflection and caliper separation under load. The single split bridge and spacerless layout, designed to enhance strength and appearance, make it a stiffer alternative to a stock caliper or a cheaper spaced-bridge unit when pedal feel under repeated hard stops matters on track days, autocross, or road-course use. Searchers looking for a 4-piston forged Wilwood caliper for a universal lug-mount brake upgrade, or a 1.00 in rotor-width Dynalite caliper for a 13.06 in rotor, will find this part's specs match that profile.
Fitment is universal, so this is not a bolt-on part for a specific vehicle. The manufacturer lists the mount location as universal with a Type III anodize finish, and the stated 5.25 in mount center means it must be paired with a caliper bracket built for your spindle or hub. Owners planning the install should expect shim work: the manufacturer's instructions call for adjusting the caliper with 0.032 inch thick shim washers, and the rotor should sit centered in the caliper opening. OEM rubber brake hoses generally cannot be adapted to Wilwood calipers, so budget for a Wilwood-compatible hose kit. Per the manufacturer, bleed the system ending with the caliper closest to the master cylinder.
The manufacturer lists this caliper as a universal, lug-style unit with a 5.25 in mount center, so it is not built for one specific vehicle. It mounts to a caliper bracket matched to your spindle or hub setup.
The manufacturer states that OEM rubber brake hoses generally cannot be adapted to Wilwood calipers. Wilwood offers hose kits designed for its caliper systems, so plan to use one of those.
Installation is a bracket-and-shim job rather than a plug-in swap. Per the manufacturer's assembly sheets, mount the caliper to the bracket, check that the rotor is centered through the top opening, and add or remove 0.032 in shim washers equally on both mounting bolts until it is. Mounting bolts must fully engage their insert nuts, and brake pads go in with the friction material facing the rotor and are secured with a cotter pin. Bleed the system starting from the caliper farthest from the master cylinder. Plan for hose and fitting compatibility before you start, since factory rubber hoses are generally not a match.
