The Wilwood Forged Superlite Internal (FSLI) 120-11126 is a four-piston racing brake caliper with 1.25-inch stainless pistons, built for 0.81-inch rotors. The manufacturer forges each aluminum body from billet and aligns the grain structure to follow the caliper contour, then anodizes it in Type III gray. Its internal fluid porting removes the external crossover tube, so there is no line to chafe, kink, or leak at the bridge. Compared with a stock single-piston unit, the four pistons spread clamping force evenly across the pad, which suits short track, late model, modified, and open-wheel use. Owners on user forums often choose this caliper for its low unsprung weight and its predictable pedal feel under repeated hard stops.
Fitment is a 3.50-inch lug mount with a universal mount side, so the caliper can be set up on either the left or right side. The manufacturer also states the two extra bleed screws allow leading or trailing mounting. Buyers searching for a 3.50 lug mount 4-piston Superlite caliper for a 0.81 rotor should confirm the bracket and spindle match their hub before ordering. For DIY work, the manufacturer's Superlite install sheets say the caliper bleed screws should point up during mounting, that the rotor should be centered by adding or removing .035-inch shims, and that OEM brake lines will not adapt to Wilwood calipers. Bleed the farthest caliper first, use Wilwood Hi-Temp 570 or EXP 600 Plus fluid, and avoid DOT 5 silicone for performance driving.
The manufacturer lists the mount side as universal. Its internal-port design replaces the transfer tube with two extra bleed screws, which allows mounting on the right or left in a leading or trailing position.
No. The manufacturer's install instructions state that OEM brake lines will not adapt to Wilwood calipers, so you will need Wilwood-compatible lines and fittings. The inlet is 1/8-27 NPT, and the manufacturer prefers steel adapter fittings.
The manufacturer recommends Wilwood Hi-Temp 570 or EXP 600 Plus for optimum performance, with EXP 600 Plus for severe braking or sustained high heat. It also states that DOT 5 silicone fluid is not recommended for racing or performance driving.
Per the manufacturer's Superlite install sheets, mount the caliper with the bleed screws pointing up and check that the rotor sits centered in the caliper window by adding or removing .035-inch shims between the bracket and spindle. Torque and alignment should be confirmed against your bracket and spindle specifications. Slide the pads in without interference, then bleed the system starting with the caliper farthest from the master cylinder, working outboard before inboard. If the master cylinder sits lower than the calipers, the manufacturer recommends an in-line two-pound residual pressure valve near the master cylinder to keep the pedal firm. Bleed again if the pedal feels spongy, check for leaks, and bed in the pads before hard use.
