The FOX Factory Series Lightweight 1.5 ZERO Intelligent Quick Switch (iQS) kit is tuned specifically for harder backcountry riding with less fatigue, without compromising durability. FOX’s 1.5 ZERO coil-sprung shocks are known for their range of control and supple ride through the chop and crust.   

The FOX iQS system is a peerless suspension package tailored specifically for your mountain sled. The electronically controlled suspension system allows you to adjust the performance of your sled in under a second. Depending on the conditions and terrain, tune your sled to provide you optimal control and comfort in any situation. Never take a break to adjust suspension again, thanks to iQS.    

We designed the coil-sprung mountain shocks with two primary objectives: weight reduction and ride performance. FOX optimizes the 1.5 ZERO coil-sprung shocks through material reduction without a sacrifice of ride quality or structural integrity. Additionally, the coil springs were redesigned to retain the same spring rate but with fewer coils and built from a lighter steel alloy. The shocks maintain a linear feel regardless of temperature fluctuation, which keeps your sled setup quick and simple. The new coils result in a spring with the same performance at half the weight.    

FOX’s position-sensitive damping technology, with origins in desert truck racing, is now applied to the Factory Race Series coil-sprung shocks. Spiral grooves inside the shock allow the oil to flow around the main piston, reducing damping force in the ride zone for a plush feel. The bypass grooves terminate through the final 30% of the travel, forcing oil to only flow through the main piston and providing a significant increase of bottom-out resistance to cushion any hard hits. Our goal was to inspire confidence next time you send it big thanks to the extra support.  

FOX iQS is an electronic modal damping control system. This system comprises a Bosch Electronic Control Unit (ECU), custom wiring harness, and electronically actuated valves integrated into each shock:    

  • The three-button switch mounted to your handlebar puts you in command of four unique shock modes. Each mode changes the character and balance of your sled by adjusting the compression damping of each shock. FOX Backcountry Team member Chris Burandt was instrumental in developing the individual settings and tuning the shocks to his refined taste. 
  • Are you scaling a near-vertical wall? Utilize lockout mode for better floatation and steering control. Lockout your rear track shock to prevent unwanted weight transfer to the rear to keep the sled planted when you twist the throttle. Worn out from a great day on the peaks and ready to motor back to the truck? Engage soft mode for a plush ride down the mountain.   

Between lockout and soft are settings to cover the full spectrum of riding from high-flying action to quick transitions boondocking through the trees. Experience a new sense of control on the snow due to less outboard weight.   

The FOX iQS system is a straightforward DIY install supported by a thorough step-by-step manual, online videos, and of course, our friendly FOX Service Center technicians.

FeaturesOptimized lightweight shock design
Spiral groove bypass
One-piece, aluminum spherical bearings
Model-specific optimized ride tune
Complete shock kit (four shocks)
Plug ‘n Play wiring harness
Bosch ECU
On-the-fly, push button adjustments
High-speed response time: full range adjustment takes place in less than one second
1.5-inch 6061-T6 aluminum type III hard-anodized bodies
LED back-lit handlebar switch
Advanced high-flow, deflective disc velocity-sensitive damping
Gas-charged mono-tube piggyback with internal floating piston (IFP) design
Fully rebuildable and re-valvable
Ski Extended Length17.630
Ski Compressed Length11.580
Ski Travel6.050
Front Track Extended Length14.280
Front Track Compressed Length9.830
Front Track Travel4.450
Rear Track Extended Length18.110
Rear Track Compressed Length11.130
Rear Track Travel6.580
Top MountEyelet
Bottom MountEyelet
Rebuild P/nFT - 803-01-379; RT - 803-01-356
Ski Extended Length17.6300
Ski Compressed Length11.5800
Ski Travel6.0500
Front Track Extended Length14.2800
Front Track Compressed Length9.8300
Front Track Travel6.5800
Rear Track Extended Length14.2800
Rear Track Compressed Length11.1300
Rear Track Travel6.5800
Fitment notesComplete Vehicle


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