Air pressure in Fox Float air shocks

[geofharries]

I am 195 lbs., 6'3" and ride a 2014 M8000 Sno Pro 162. I've got questions about shock travel and air pressure.

I come from mountain biking, and so am used to setting up my shocks for my weight. When I bought my sled, the dealer told me most people don't touch their sled shocks. So, I left as is.

Something I noticed this weekend while starting up my machine is that my front and rear shock travel is quite different. I had put a zip-tie on each to measure travel sometime in late spring. The rear (which makes sense, as it carries more weight) was almost bottomed out while the front was quite a bit higher. See attached photos.

Is this normal? Do you recommend I try to lose some air in the front and add some to the rear so they are more balanced or does it really matter?

 

[greenmtnboys]

I am 195 lbs., 6'3" and ride a 2014 M8000 Sno Pro 162. I've got questions about shock travel and air pressure.

I come from mountain biking, and so am used to setting up my shocks for my weight. When I bought my sled, the dealer told me most people don't touch their sled shocks. So, I left as is.

Something I noticed this weekend while starting up my machine is that my front and rear shock travel is quite different. I had put a zip-tie on each to measure travel sometime in late spring. The rear (which makes sense, as it carries more weight) was almost bottomed out while the front was quite a bit higher. See attached photos.

Is this normal? Do you recommend I try to lose some air in the front and add some to the rear so they are more balanced or does it really matter?

We are running 95 lbs in the skis,140lbs in the front and 95lbs in the rear of the skid. The best is to play with them till it handles the way you like but this is a good starting point I am riding a 17 m8000 162 and also weigh about 195

 

[geofharries]

Thanks, I’ll go ahead and start fiddling. Appreciate the comparisin.

 

[boondocker97]

You'll get recommendations all over the map and the snowmobile will handle very differently with different setups. I would expect greenmtnboys' setup transfers weight aggressively to the rear and wheelies a fair amount. I've observed the 36" front ends on 2016+ sleds take a bit more ski shock pressure to resist roll than the 38" front end on your sled.

These were my notes from another thread on suspension setup on my 2014 162:

"I am 260 without gear. I have a 2014 pro-lite so the sled is a bit lighter, but here's what i found with the stock shocks. For ride quality in rough terrain I liked 70psi in the front shocks, center shock with 1" of threads showing below the spring preload rings, and 140psi in the rear shock. I ended up going to 75 in the front shocks to get the body roll down a bit in the corners on the trails, but it was starting to take away from the ride and bump absorption on the side hills.

For deep snow back the center shock off to 1/2" of threads below the center shock preload ring. Gets up on the snow MUCH better and keeps the front end down and controllable. I also run 145-150 in the rear shock to help keep the front end down with the extra power of the big bore.

If you get to the point where you want to upgrade the ride there is some good information here: http://www.snowest.com/forum/showthread.php?t=376962"

For your weight I Recommend starting 65-70psi in the front ski shocks for decent ride quality and still hold up when on edge on one ski. 125-130 or so in the rear track shock. Decrease rear shock pressure for smoother ride or increase weight transfer. Increase rear shock pressure to decrease bottoming or to help hold the front end down. Set air pressures with whichever shock you are checking off the ground with no load on it and at the same general temperature you are riding at. I roll my sled over on its side in the mountains where I am riding when adjusting mine.

Being a 2014 the shocks on your machine are likely due for some service. At a minimum the air seals should be cleaned and re-lubed to avoid sticking and leaks from frozen moisture.

 

[geofharries]

Thanks. Yes, I’m not sure if the shocks have had maintenance service like that done. I’ll check with the dealer, as they may have records (I bought it used).

 

[JB_M]

I just picked up a 2013.

I'm 210 lbs with no gear.

I should say, I'm a novice wrenching on sleds but am fairly mechanically inclined, have had quads, boats, truck, bikes.

It came with 65 psi in each ski, preload on center shock cranked as high as possible and rear shock around 100.

It felt really sloppy and didn't lift/jump on edge like i thought it should.

Tweaking this weekend I got 95 in each ski, center shock preload at halfway, and gonna set the rear (I'm not sure, probably 120 or 130?).

 

[boondocker97]

95 is pretty stiff in the fronts unless it's a 4stroke. In which case you might need more! Adjust up the rear until you aren't bottoming out frequently. Can add a little more to the rear to help control ski lift as needed, but too much will make a harsh ride, not transfer well, and washout on side hills.

 

[JB_M]

Appreciate the info.

It's just a starting point. When I got it the rear was jacked up on air and spring preload, to the max, with the skis at 65 psi.

It felt weird and lazy, just trying to start from a neutral place.

I'm going to have a bottle of N2 in the truck when I go riding this week to make adjustments.

Hey one (the only?) perk of being an ac guy.

 

[koolaid]

I will second that 95 in skis is far too high. I am 210 with gear and run 65 in skis and 140 in rear skid and have found it to be playful, gets on edge quick and not a wheelie monster.

 

[geofharries]

Thanks everyone for your input.

I checked my shocks and skis last night. The rear shock was set at 120 PSI and the ski shocks also at 120 PSI (!). The coil shock was set pretty soft, with barely any pre-load.

It's no wonder I found the machine overly difficult to get on edge without some serious weight shifting compared to others I've tried. The front end was always very harsh over the bumps too.

So, I increased the rear shock to 140 PSI and decreased the ski shocks to 70 PSI. I also narrowed the ski stance to its narrowest option, which I am sure helps as well.

Now it rolls quite easily side to side and gets up on edge without much effort. WAY better.