The Wilwood 120-11129 is a Forged Superlite Internal (FSLI) four-piston caliper with stainless steel 1.38-inch pistons, a stress-flow forged aluminum body, and a Type III anodized gray finish. Its internal fluid routing means there are no external cross-over tubes to route, clamp, or damage. The manufacturer's stated advantage of forging over a machined block billet is a stronger, more rigid body, which is what justifies the premium over a stock or cast caliper for repeated hard braking on track, short-track, or open-wheel cars. Buyers searching for a 1.10 rotor width, 13.06 inch Superlite four-piston caliper for a race build will find the Wilwood FSLI platform a common choice. Fitment is universal, with a 3.50 inch lug mount center and a 7420 pad style, so it suits custom brackets and bell-mounted race setups rather than a specific production model.
Because the mount side is universal, the same caliper can go on either corner of the car, which simplifies spares and rebuilds. Pad replacement is straightforward with 7420 pads, and the manufacturer's pad part numbers are listed by compound for this family. The 1/8-27 inlet thread matches common Wilwood fittings and hard lines, so most owners plumb it with steel braided line and adapter fittings. Owners on user forums commonly pair this caliper with a matching rotor and bracket, so confirm bracket and hub clearance before you order.
The manufacturer lists the mount side as universal for this Forged Superlite Internal family, so it is not sold as a left or right unit. Confirm that your bracket and hub clearance suit the corner you are installing it on.
The manufacturer's Forged Superlite Internal listings call for a 13.06 inch rotor diameter and a 1.10 inch rotor width. Verify your rotor dimensions before ordering, since the caliper is sized to that rotor.
The manufacturer specifies a 1/8-27 inlet thread for this Superlite caliper family. Use steel adapter fittings or PTFE tape on pipe-thread connections as the manufacturer's install sheets describe.
The manufacturer's install sheets for Forged Superlite kits say the work should be done only by people experienced with disc brake systems, so this is best suited to a competent DIYer or a shop. Mount the bracket squarely against the bell bosses, make sure every mounting bolt fully engages its threaded hole, and set pad height with shims between the caliper and bracket. Connect the 1/8-27 hard line with the correct adapter and sealing method, then bleed all four corners and confirm the bottom bleed screws are tight before road testing. Common gotchas include incomplete bolt engagement and leaks at the inlet, so pressure-test the system and recheck torque after the first heat cycle.
