Wilwood 120-11129-BK Forged Superlite Internal FSLI Brake Caliper Black 1.38" Pistons 1.10" Disc

The Wilwood 120-11129-BK Forged Superlite Internal (FSLI) Brake Caliper is a high-performance, black Type III hard anodized racing caliper featuring 1.38" piston bores designed for use with 1.10" wide brake rotors. Part of the legendary Superlite series, the FSLI represents the latest evolution in Wilwood's competition brake caliper lineup, trusted across short track, late model, modified, and open wheel racing, as well as road racing, rally, off-road, and performance driving applications.

The defining advancement of the FSLI over earlier Superlite designs is the internal fluid porting system, which completely eliminates external fluid crossover tubes and the vulnerabilities that come with them. In their place, two additional bleed screw assemblies are incorporated, allowing the caliper's symmetrical piston bore layout to be mounted in either a left or right position, in leading or trailing configurations — providing maximum installation flexibility.

The caliper body itself is stress-flow forged from premium-grade aluminum alloy billets, a process that re-aligns the metal's internal grain structure to follow the contour of the caliper body. This eliminates the grain interruptions caused by straight-block billet machining, resulting in an exceptionally strong and rigid caliper housing. Computer-generated solid modeling and finite element stress analysis guided the FSL body design, incorporating closed-end bridges with radial transitions to the piston housings — eliminating machined steps and sharp shoulders for maximum deflection resistance under braking loads.

Key Features:

• Forged aluminum alloy body with Type III black hard anodized finish
• Internal fluid ports eliminate external crossover tubes for a cleaner, more reliable setup
• Symmetrical piston bores allow left/right and leading/trailing mounting positions
• 1.38" / 1.38" dual piston bores; compatible with 1.10" wide brake rotors
• Rotor diameter range: 11.75" minimum to 13.06" maximum
• Uses 7420-type bridge bolt brake pads (same as Superlite 6-piston calipers)
• Total pad area: 8.2 sq in; total pad volume: 4.9 sq in
• Replaceable SRS stainless steel bridge plates resist pad gouging and eliminate pad rattle
• Center bridge bolts replace cotter pins for added support and quick pad access
• Stainless steel pistons resist corrosion and reduce heat transfer from pads
• High-temperature square-faced O-ring seals for positive sealing and controlled piston retraction
• Two-piece bleed screw assemblies for long service life and easy replacement
• Direct replacement for all Wilwood Superlite calipers with 3.50" centered mounting tabs
• Compatible with the full Wilwood PolyMatrix brake pad compound lineup
• Instructions included

The Wilwood FSLI caliper combines race-proven structural engineering with practical serviceability features, delivering consistent, fade-resistant stopping power with reduced pedal travel — making it an ideal upgrade for serious competition and high-performance street builds.