Fox Racing Shocks 981-02-393-1 4.0 Factory Race Series 18in External Bypass Piggyback Shock Custom Valving

The Fox Racing Shocks 981-02-393-1 is a Factory Race Series 4.0 external bypass piggyback reservoir shock featuring 18 inches of travel and a 5-tube bypass configuration with custom valving (3 compression zones / 2 rebound zones). Engineered for serious off-road competition, this shock delivers precise, tunable damping performance across the full range of suspension travel.

Key Specifications:

• Body Diameter: 4.0 inches
• Stroke: 18.0 inches
• Extended Length: 46.54 inches
• Collapsed Length: 28.54 inches
• Shaft Diameter: 1-1/8 inch (1.125 in.)
• Bypass Tubes: 5 (3 compression / 2 rebound)
• Valving: Custom
• Reservoir Type: Piggyback
• Mount Style: Eyelet / Eyelet
• Finish: Black anodized aluminum components / Zinc-plated steel body

Key Features:

• Zinc-plated seamless alloy shock body for long-lasting durability
• Industry-leading 17-4 H900 stainless steel shaft for superior strength and corrosion resistance
• Fox Racing–developed shock oil formulated for consistent, high-performance damping
• Black anodized CNC machined aluminum components for reduced weight and precision fit
• 100% rebuildable and serviceable design for extended service life and tunability
• Teflon-lined heat-treated spherical bearings for smooth, low-friction operation
• Redundant sealing system for reliable, long-lasting performance in harsh conditions
• External bypass tubes allow independent tuning of low-speed and high-speed damping zones

Sold individually. The Fox 981-02-393-1 is the custom-valved variant of the 981-02-393, ideal for builds requiring application-specific damping calibration tuned beyond standard factory settings.