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Wilwood Forged Superlite FSLI Caliper with Symmetrical 1.12-Inch Pistons for Short Track and Road Race
The Wilwood WIL120-11125 is a Forged Superlite FSLI single caliper with dual symmetrical 1.12-inch pistons and a 0.81-inch disc width capacity. The Forged Superlite series is the benchmark in short track, late model, modified, and open wheel competition, and has earned equal prominence in road race, off-road, rally, and sport driving applications. The FSLI designation marks the latest evolution of this caliper family: Wilwood redesigned it with internal fluid ports that eliminate the external fluid crossover tube, removing a potential failure point from the caliper body. The crossover tube has been replaced by two additional bleed screw assemblies, which allows all symmetrical piston bore models in this series to be mounted in either a right or left, leading or trailing position without compromising fluid routing. The WIL120-11125 is sold as a single caliper and should be ordered in pairs for most axle applications.
Key Features
- Internal fluid ports eliminate the external crossover tube for a cleaner, more durable design
- Two bleed screw assemblies allow leading or trailing, left or right mounting in any position
- Symmetrical 1.12-inch piston bores for even clamping across the pad surface
- Fits 0.81-inch wide rotors
- Forged billet aluminum caliper body for maximum strength-to-weight ratio
- Benchmark caliper for short track, late model, open wheel, road race, rally, and street performance
- Sold as a single caliper
Specifications
| Detail | Value |
|---|---|
| Part Number | 120-11125 |
| SKU | WIL120-11125 |
| UPC | N/A |
| Piston Bore | 1.12 in (symmetrical) |
| Rotor Width Capacity | 0.81 in |
| Fluid Port Design | Internal (FSLI) |
| Mount Orientation | Left or Right, Leading or Trailing |
| Bleed Screws | 2 (replaces crossover tube) |
| Caliper Material | Forged Billet Aluminum |
| Quantity | 1 caliper (order 2 for axle) |
What's Included
- 1 x Wilwood WIL120-11125 Forged Superlite FSLI caliper
- Bleed screws installed
Related Parts on Our Site
- Wilwood 120-11126 — Forged Superlite FSLI 1.25in Pistons, 0.81in Disc
- Wilwood 120-11128 — Forged Superlite FSLI 1.38in Pistons, 0.81in Disc
- Wilwood WIL220-7496 — 1/4-28 Black Bleed Screw
About Wilwood
Wilwood Engineering has been designing and manufacturing high-performance brake components in Camarillo, California since 1977. Every Wilwood caliper is machined from premium forged billet aluminum and validated through rigorous motorsports testing. Wilwood products are trusted by professional teams across SCCA, NASA, and multiple short track and oval disciplines.
Frequently Asked Questions
What is the Wilwood WIL120-11125?The Wilwood WIL120-11125 is a Forged Superlite FSLI single caliper with dual symmetrical 1.12-inch pistons and a 0.81-inch rotor width capacity. It features internal fluid ports that eliminate the external crossover tube, allowing left or right, leading or trailing mounting with two bleed screw positions.
What does FSLI mean on this caliper?FSLI stands for Forged Superlite with Internal fluid transfer ports. Wilwood redesigned the classic Superlite caliper body to route brake fluid internally between the two piston bores, eliminating the external crossover tube that was a potential leak or damage point on earlier Superlite models.
Can this caliper be mounted on either side of the axle?Yes. The symmetrical piston bore and dual bleed screw design allows the WIL120-11125 to be mounted in a leading or trailing position on either the left or right side of the axle without rerouting fluid lines.
Is this caliper sold as a pair?No. The WIL120-11125 is sold as a single caliper. Order two for a complete axle application, and confirm rotor width and bracket clearance for your specific application before ordering.
What rotor width does this caliper fit?The WIL120-11125 is designed for 0.81-inch wide rotors. Using a rotor of a different width may result in incorrect pad-to-rotor contact and uneven wear.
What thread size are the bleed screws on this caliper?Wilwood Superlite FSLI calipers use 1/4-28 threaded bleed ports. Replacement bleed screws are available separately as Wilwood part number 220-7496.
What piston material are used in this caliper?Wilwood uses phenolic composite pistons in its Superlite line. Phenolic pistons provide excellent thermal insulation to protect brake fluid from heat fade while maintaining dimensional stability under load.
What brake fluid is recommended for this caliper?Wilwood recommends its own EXP 600 Plus or Hi-Temp 570 brake fluid for racing applications, and a DOT 4 or DOT 5.1 fluid meeting or exceeding FMVSS 116 for street use. Never mix DOT 5 silicone fluid with glycol-based fluids in the same system.
Installation Instructions
- Confirm rotor width (0.81 in) and bracket offset before ordering. Fabricate or source the appropriate caliper mounting bracket for your application.
- Mount the caliper bracket to the upright or knuckle and torque to specification.
- Install brake pads into the caliper and position the caliper over the rotor.
- Torque caliper mounting bolts to the bracket specification. Verify even pad-to-rotor clearance on both sides.
- Connect the brake line to the inlet port. Torque the banjo bolt or line fitting to specification with a new copper washer.
- Bleed the caliper using the bleed screw on the outboard side, then verify a firm pedal with no spongy feel before test driving.
- Bed in pads per manufacturer instructions before full-load use.
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