FOX 4.0 Factory Series Bypass Piggyback Shocks

Code: N/A


In Stock


The FOX 4.0 Factory Series Bypass shock is the ideal position-sensitive shock for lightweight unlimited offroad racecars and pre-runners.

Bypass shocks allow precise adjustment of multiple stages of compression and rebound damping. The 4.0 Factory Series Bypass shock adds another competitive option to FOX’s already extensive bypass shock lineup. The expanded volume provides a wider damping range and increased cooling-optimizing the suspension and increasing the vehicle’s capabilities. The 4.0 Bypass shock uses the same extended and compressed lengths as the 3.5 Factory Series Bypass for easy upgrading.

The 4.0 Bypass shock comes standard with FOX’s Rotating Body Cap (RBC) technology that allows quick and easy positioning of the shock body with simple hand tools. RBC eliminates the need of re-clocking body cap threading to achieve shock body rotation for chassis clearance issues. The 1.125′ hard chrome-plated 17-4 H900 stainless steel shock shaft provides increased strength and stiffness.

Multiple stroke lengths are available with a large 3.5 piggyback reservoir and 4 or 5 tube layouts. FOX also offers many custom options to maximize your suspensions performance while adhering to the vehicle’s space restrictions. Options include custom bypass tube layouts, External Cooling Systems (ECS), remote reservoir mounting, and eyelet lengths.

  • Smooth-bore, clear coated, zinc plated, honed seamless alloy bodies
  • Black anodized 6061-T6 billet aluminum
  • 1-1/8″ hard chrome plated stainless steel 17-4 H900
  • Sold individually

CLICK HERE for more info on the FOX website.

Body Smooth bore and honed seamless steel
Body Plating Zinc plated for a long-lasting finish
Components Black anodized, CNC machined 6061-T6 billet aluminum
Piston Stainless steel for improved performance at high temperatures*
Valving Tunable, velocity sensitive deburred valve shims
Seals High-temp Viton® redundant sealing pack system with main seal, wiper seal and scraper seal*
Oil JM92 Advanced Suspension Fluid for improved performance at variable temperatures
Shafts 17-4 H900 hard chrome plated stainless steel
Bearing Spherical, PFTE-lined, heat-treated alloy steel


  • On custom shocks, FOX charges a $50 surcharge for different valving, rod ends, bypass tube locations, coatings, etc. then what comes standard. There may be other costs associated with custom shocks.