FOX Float Airshox

SnowTest September 8, 2004 1
Last year we introduced you to the new FOX FLOAT AirShox that replace the traditional heavy coil spring found on ski shocks absorbers with...

Last year we introduced you to the new FOX FLOAT AirShox that replace the traditional heavy coil spring found on ski shocks absorbers with an adjustable “air spring”, an air chamber that replicates and improves upon the spring action of the coil spring.

Typical shock absorbers on the front suspension use coil-over springs to store and release the energy of the bumps, with the shock absorber controlling the rate of absorption and subsequent release of the energy stored in the springs. This has proven to be economical, but steel wire coil springs weigh approximately six pounds on a typical snowmobile. The AirShox eliminate the heavy coil springs, along with about six pounds of unsprung weight (what’s lighter than air?) for a HUGE difference.

FLOAT stands for Fox Load Optimizing Air Technology. This is pretty much a FOX high-pressure internal floating piston shock with a second tube covering the previously-exposed shock rod; an adjustable air volume sleeve on the outside of the aluminum hard-anondized shock body.

Inside you’ll find an adjustable force-sensitive shim damping system (just like we’re used to) and a hard-chrome shaft. They are, of course, revalvable and rebuildable. The FLOAT design also incorporates FOX’s exclusive “Samurai Wiper”. This patented scraper-lip technology virtually eliminates the entry of water contaminating the oil in the shock, which translates to fewer rebuilds and more riding time.

Now for 2005, Arctic Cat offers the FLOAT AirShox as standard issue on their King Cat, M-Series Limited models, and Firecat SnoPro models. In addition, Yamaha has added the FLOAT Air Shox as an authorized Yamaha accessory for many of their four-stroke models.

How do they work? We installed a set onto one of our long term test sleds, a early-build 2004 Arctic Cat Firecat F6. Installation was very easy, a matter of unloading each ski and removing the shock bolts and shocks. Installation consists of adapter bushings and the shocks, and re-torquing the bolts.

The AirShox are adjustable via an air pump, so there is a small amount of initial set-up where you calculate your starting air pressure (pre-load) and using the air pump to apply this pressure to the FLOAT chamber. Since our riders tend to be heavier than the average bear, we set our AirShox to 60 psi (based on the formula provided by Fox, 50 psi standard for the Firecat plus 10 psi for added rider weight).

Our test riders immediately noticed the difference. The AirShox provide a progressive force vs. travel curve, compared to a straight rate nature of coil springs. What this means is the AirShox are a bit softer and more compliant for about the first 60% of the suspension travel, but quickly build force during the final 30% of shock stroke (and suspension travel). This virtually eliminates harsh bottoming of the suspension, and from what we experienced provided a “bottomless” feeling to the front suspension.

Adjustments in air pressure simply move this curve up and down. While we experimented a little with higher and lower air pressures, we found 60 psi to be just right for our trail riding. The factory-set 50 psi is intended for riders in the 180-190 pound range, and would provide excellent all-around performance for the majority of riders.

Almost everyone asks about the durability of the air spring, and if changes in temperature affect them. Theoretically, if you set the air pressure in the garage at +60 and go out and ride the sled at –20, there will be a change in air pressure just like the pressure in the tires on your car, but in practice this simply wasn’t an issue for us. Once we decided upon 60 psi as being high enough so it didn’t bottom and wasn’t harsh, yet low enough for a compliant ride, we left the pressure alone. We checked the pressure every couple of weeks with no change. They held their pressure all season long, and continue to do so on the shelf to this day. Pressure loss seems to be a moot point.

When checking the pressure of the shock with the pump, it takes a couple psi to fill the hose on the gauge so take this into consideration. To increase the pressure you stroke the pump. To decrease pressure, you press the pressure release valve. Very straight-forward and simple.

Do you have to carry the rather delicate air pump/gauge with you? We didn’t. Fox suggests carrying it with you on the first ride, but we started out cautiously and quickly discovered our initial settings were more than adequate for trail use.

FOX calls for routine service of the AirShox, just like any high-performance shock absorber. The air pressure should be checked at least once every month. Air sleeve maintenance should be performed at least once a year, and is something that most of us can do. Detailed instructions on this are provided in the owner’s manual, consisting of minor disassembly of the air sleeve, cleaning, inspection and lubrication, all fairly easy if you’re capable of something like performing track tension and alignment.

The IFP portion of the shock should be rebuilt (by a qualified technician due to the high-pressure nitrogen) every 3000-5000 miles. The FLOAT AirShox offer the highest quality materials and coatings Fox offers, so they’re far more durable than the Fox shocks of years past, and water ingestion appears to be greatly reduced on their latest offerings.

All of our worries proved to be unfounded, as the FLOAT AirShox performed exactly as we had hoped for. They reduced the already light F6 by six pounds, and this was all unsprung weight. Yes, you do notice six less pounds of unsprung mass. The suspension action is more compliant in the stutters AND nearly bottomless at full stroke. The air pressure didn’t vary enough to matter, and they proved most durable. This year we will be adding FLOAT AirShox to more of our test sleds. We view their being offered by Yamaha and Arctic Cat as evidence they’re worthy of your consideration. We suspect this will quickly become the new standard in mountain sled front suspensions for the weight, performance and durability.

All FLOAT AirShox will come with a FREE 90-day revalving guarantee and a 1-year limited factory warranty. Each FLOAT AirShox system will include two front ski FLOAT AirShox (with mounting hardware) and a FOX HP Air Pump. Kits are currently available to fit many popular performance and mountain sleds. Retail pricing is $895 per package, which includes two FLOAT AirShox, the pump/gauge and all hardware/bushings need for your installation. To order contact your authorized FOX dealer (Carver Performance at 888-349-7469 / or call 1-800-FOX-SHOX (

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