Wilwood 120-14439-BK Forged Narrow Superlite Dust Seal Disc Brake Caliper - 4R Black

The Wilwood Forged Narrow Superlite 4R Dust Seal (FNSL4R-DS) is a high-performance disc brake caliper engineered for demanding street and competition environments. The addition of Wilwood's exclusive wiper dust seal enables these calipers to perform reliably in applications requiring environmental sealing, making them ideal for a broad range of vehicle builds where exposure to the elements is a concern.

The FNSL4R-DS caliper body starts at just 4.9 pounds and is the result of computer-generated solid modeling and FEA (Finite Element Analysis) stress analysis technology. Each body is stress-flow forged from premium-grade aluminum alloy billets, a process that re-aligns the metal's internal grain structure to flow within the contour of the caliper body — eliminating the structural weaknesses that result from machining straight-block billet. The result is one of the strongest aluminum caliper bodies available.

Key Features:

• Exclusive wiper dust seal for environmental protection in sealed or harsh-environment applications
• Stress-flow forged aluminum alloy body — optimized grain structure for superior strength and rigidity
• Six-piston differential bore configuration for balanced clamping force and even pad wear under sustained high-heat conditions
• One-piece stainless steel pistons standard — chosen for low heat transfer properties and corrosion resistance
• Thermlock piston upgrade available — multi-part design creates a thermal barrier to reduce heat transfer to seals, fluid, and caliper body, minimizing pedal fade
• SRS (Spring-loaded Retaining System) bridge plates eliminate pad gouging wear on the bridge, reduce pad rattle, and dampen harmonic vibrations that contribute to brake squeal
• Two-piece bleed screws on each end protect against track debris and other damage sources
• Internal fluid crossovers for a clean, protected hydraulic circuit
• High-temperature square-faced bore seals maximize sealing area and provide controlled piston retraction on brake release
• Black powder coat finish for durability and a clean appearance
• Compatible with the full range of Wilwood brake pad compounds to match response and heat range for any competition or performance driving application

The Wilwood FNSL4R-DS delivers race-proven braking performance with big brake stopping power, making it a top choice for custom performance builds, track cars, and sport driving applications that demand reliability in extreme conditions.