Wilwood Caliper-Forged Superlite 1.38in Pistons .81in Disc

Wilwood Forged Superlite FSLI Caliper with Symmetrical 1.38-Inch Pistons for Short Track and Road Race

The Wilwood WIL120-11128 is a Forged Superlite FSLI single caliper with dual symmetrical 1.38-inch pistons and a 0.81-inch disc width capacity. The 1.38-inch bore is the largest symmetrical piston option in the FSLI series at this rotor width, generating the highest clamping force for applications requiring maximum braking power with an 0.81-inch rotor. The Forged Superlite series is the benchmark in short track, late model, modified, and open wheel competition and has widespread use in road race, off-road, rally, and performance street applications. The FSLI design routes brake fluid internally between the two piston bores, eliminating the external crossover tube and replacing it with two bleed screw assemblies. This allows the WIL120-11128 to be mounted in any leading or trailing, left or right position on the axle without fluid routing changes. Sold as a single caliper.

Key Features

• Symmetrical 1.38-inch pistons for the highest clamping force in the FSLI 0.81-inch series
• Internal fluid ports eliminate the external crossover tube for improved durability
• Two bleed screw assemblies allow leading or trailing, left or right mounting without rerouting lines
• Fits 0.81-inch wide rotors
• Forged billet aluminum body for maximum strength-to-weight ratio
• Suitable for short track, late model, open wheel, road race, rally, and street performance
• Sold as a single caliper

Specifications

What's Included

• 1 x Wilwood WIL120-11128 Forged Superlite FSLI caliper
• Bleed screws installed

Related Parts on Our Site

• Wilwood 120-11125 — Forged Superlite FSLI 1.12in Pistons, 0.81in Disc
• Wilwood 120-11126 — Forged Superlite FSLI 1.25in Pistons, 0.81in Disc
• Wilwood WIL220-7496 — 1/4-28 Black Bleed Screw (replacement for this caliper)

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 motorsports testing. Wilwood products are trusted by professional teams across SCCA, NASA, and multiple short track and oval disciplines worldwide.

Frequently Asked Questions

The Wilwood WIL120-11128 is a Forged Superlite FSLI single caliper with dual symmetrical 1.38-inch pistons and 0.81-inch rotor width capacity. It provides the highest clamping force of the three symmetrical FSLI models at 0.81-inch rotor width, with internal fluid ports and dual bleed screw positions for flexible mounting.

A larger piston bore generates proportionally more clamping force at the same hydraulic line pressure. The 1.38-inch WIL120-11128 produces more clamping force than either the 1.12-inch WIL120-11125 or the 1.25-inch WIL120-11126 at the same 0.81-inch rotor width. Use the larger bore on the axle that requires more braking bias, such as the front axle in a front-heavy application.

Yes. The dual bleed screw design allows the WIL120-11128 to be mounted in a leading or trailing position on either the left or right side of the axle without changing fluid line routing.

No. The WIL120-11128 is sold as a single caliper. Order two for a complete front or rear axle setup.

The WIL120-11128 accepts 0.81-inch wide rotors. This is the same rotor width as the 1.12-inch and 1.25-inch FSLI variants, so rotor selection is consistent across the three symmetrical bore models at this width.

Wilwood Superlite FSLI calipers use 1/4-28 threaded bleed ports. The correct replacement bleed screw is the Wilwood WIL220-7496, available separately on our site.

Yes. Wilwood makes additional Superlite variants with mixed piston bore sizes and wider rotor width capacity for applications requiring different pad contact areas or thicker rotors. Contact Wilwood or consult their full product catalog for the correct model if your application uses a rotor wider than 0.81 inches.

The Wilwood Forged Superlite accepts Wilwood BP-10, BP-20, and BP-30 series pads as well as many third-party compounds in the correct tab pattern and width. Choose the compound based on your operating temperature range, rotor material, and use case from street to endurance racing.

Installation Instructions

1. Confirm rotor width (0.81 in) and determine the required bracket offset for your application.
2. Mount the caliper bracket to the upright or knuckle and torque to specification.
3. Install brake pads into the caliper and position the caliper over the rotor on the bracket.
4. Torque caliper mounting bolts to bracket specification and verify even pad-to-rotor clearance.
5. Connect the brake line to the inlet port using a new copper sealing washer. Torque to specification.
6. Bleed from the outboard bleed screw and verify a firm, consistent pedal before driving.
7. Complete a proper pad bed-in procedure before sustained hard braking use.