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Ski-Doo Fox Float 3 Evol Set Up
- Thread starter Norona
- Start date
J
Love ya Dave but a lot of this isn't right as far as your explanation. Plenty of monotube shocks work just fine from a functional standpoint, and depending on the valving of the damper piston, it can be just as smooth as a piggyback shock. To my point, many high end shocks are monotube in other applications. (see: Indycar dampers, NASCAR dampers, rally car dampers etc). Functionally they are similar, both IFP based dampers, only difference is going to be oil volume and the extra "room" allowing the engineer the ability to run the oil through some extra compression damping circuit (QS3 in this case)
Besides looks (subjective), another reason piggyback is going to be better is really heat dissipation (more oil, more surface area), though this isn't a huge deal in the mountain sled world. Point is, the feel differential has nothing to do with the "oil having nowhere to go". The oil volume displaces the IFP which is nitrogen backed. Depending on valving, IFP pressure etc you can match the damping curve a piggyback shock to a monotube shock - though due to lower IFP pressure you may have a slightly higher chances of cavitation (EG, the IFP doesn't move back to equalize pressure fast enough...again, if trying to run super low IFP pressure.) This can be true regardless of piggyback or monotube - an IFP is an IFP. Happy to explain this in more detail if you like
The way you explained the air spring curve isn't terrible, but not quiet right either. Technically speaking, the EVOl chamber actually works similar to the way the damping IFP works. By adding air to the EVOL chamber, you are effectively putting more pressure behind an internal floating piston (this time on the spring side of the equation). The pressure in front of the IFP must be greater than the pressure behind the IFP for it to move. When it moves, it creates more and more volume changing the air spring curve.
In laymans terms, the EVOL chamber offers the rider the ability to adjust the spring curve later in the stroke. It is *position sensitive* spring curve adjust. Want a more linear curve, pull air out of the EVOL chamber. Want a more progressive spring curve, put more in.
Finally, I do not want to be on the 3 setting for the whoops, but I do for the corners. The QS3 is a low speed compression adjust. Firming up the damping by ~20% and ~80% respectively (2 vs 3). In 3 the sled stays a lot more level, but a lot more force is transferred to the rider. 2 kind of a nice balance. Obviously, this part we can debate
W
Thanks for clarifying about the QS3 being a slow speed compression damping, haven't been able to find that info anywhere. I am looking at putting on new shocks on a brand new G4. I am new to both Skidoo and air shocks -for sledding, (I mountain bike as well), having only run coilers on an RMK before this.
Not to thread hijack, but I was wondering if the QS3 adjustment would help for adding heavy loads to the sled such as doubling up for sled skiing? Having read almost every post on these Fox shocks for the G4, what kind of fiddling around with the air pressures do you guys experience when compensating for altitude and cold? I am a fan of set and forget, but also intrigued by the adjustability of these air shocks.
Also very intrigued by Tom's E-motion...
Not to thread hijack, but I was wondering if the QS3 adjustment would help for adding heavy loads to the sled such as doubling up for sled skiing? Having read almost every post on these Fox shocks for the G4, what kind of fiddling around with the air pressures do you guys experience when compensating for altitude and cold? I am a fan of set and forget, but also intrigued by the adjustability of these air shocks.
Also very intrigued by Tom's E-motion...
J
Hey dude!
Some great questions...
I came into the sport from both mountain biking and skiing, so yeah, I totally sympathize to your situation.
Few thoughts...
1) QS3 is excellent for a sled ski application. I do think getting a custom QS3 setup (valved for what you are doing) will make a big difference. Tom is the only guy selling the torsion bar delete with an air spring, and for that use, yeah, its rad for sled skiing/hauling big loads. He also has the QSL (a lockout version of the QS3 - its just a firmer "3" position). Everyone knows I help him out, so I have bias here that I'm not hiding. But I also came to him as a customer first...
2) I set my pressures outside at 6,500 feet. Never mess with them. Yeah, they are a bit different at 10,000 feet, but I never notice. If I adjusted them in a warm garage, sure, it'd be different at 15 degrees. But so long as they are setup close to the temp/elevation, you'll never mess with them. They aren't hyper sensitive. They are less sensitive than your mountain bike (higher volume chamber)...that should tell you what you need to know.
W
Good to know. Yeah, I kinda picked up that you are biased towards Tom's stuff, but then again, it seems that everyone who has it is as well…
So to clarify, the QS3 on a higher setting will impact slow speed compression, meaning with a heavier weight it will act to raise the force required to react to body roll, almost acting like increasing sag? I know that last part about sag probably isn't the best way to describe it, I'm just trying to wrap my brain around what it will do.
With the Emotion skid, what would that QSL do for it/me?
How is the e-motoion better than Fox Doo shocks valved for me?
Thanks for your help. I've actually emailed and called a couple times and haven't heard back.
J
Thank you for this. Helps show me where my articulation sucks.
So the e-motion skid (now called "evolution" skid) is really just designed to delete the torsion bars and rely on an air spring instead. To add, Tom's uses a new rear arm and billet rocker arm to vary the leverage ratio (which is an awesome but lesser talked about attribute) but again, the big difference is *spring rate* through the cycle of the shock's stroke. This is designed to get the sled ontop of the snow as quickly as possible, control transfer very effictively, while still offering a very compliant ride on trail.
Tom uses Fox stuff, valved for his application, but valving and spring rate are completely independent.
Put another way, the way compression damping acts with torsion bars is going to be the same as the way it acts with an air spring. That said, obviously, an OEM damper is many steps behind a Fox damper with respect to refinement, quality and control.
In both cases, (torsion bar or air spring using Fox QSL) when you go to "lockout" the rear end still sags to the point it otherwise would, but the force required to move oil through the compression circuit, at low shaft speeds, is very high. This helps control transfer in a very cool way. Obviously, not for everyday riding, but if its steep (and relatively smooth) its rad. Its also rad for steep climbs while doubling...though in this case, I'd rather put a bit more air in the main chamber and call it good (in the "2" position)
Again, I can't reiterate enough how cool it is to be able to quickly manipulate spring RATE and CURVE. This is exclusive to air, at least with respect to being able to change these attirbutes in a matter of minutes.
This might be one of those things better suited to a phone call! 9702190258
W
Thanks for explaining this better to me. Your articulation is quite good (especially for the forum, lol). My understanding of snowmobile suspension is what sucks. I really appreciate you taking the time to explain this.
J
Just wanted to follow up with one more point...
Damping is *speed sensitive*. This means damping controls the input forces depending on the time horizon those forces are applied to the shaft. Put another way, damping (specifically compression) is dependent on the speed of the shaft (not your riding speed). This is why when we apply more damping it does not effect sag, but it may effect how long it takes for that sag to be achieved. There are exceptions to this, as there are position sensitive dampers out there as well - but we will ignore that in this exercise.
A spring is *position sensitive* in that it reacts differently to a set force depending on where it is in its position (how much the spring is compressed). A coil spring is generally linear. Air spring generally progressive, though both can be manipulated. For instance, Exit often uses a progressive coil spring package, and many Fox products can be setup super linear if you set the EVOL chamber up with minimal amount of pressure.
The idea is to have the spring support the chassis and rider, with the appropriate rate to keep make the most effective use of the available travel (and intended goal) whereby damping is the way that travel is controlled. Again, this too is going to be dependent on application and goal.
There are areas where damping can be used to some extent where the spring is falling short or a spring can be used where the damping is falling short, but ideally you have both tuned specifically for the job at hand. Again, this is why I'm such a big fan of air in a skid application (progressive=good, easy to adjust depending on conditions/environment=good). Custom valved QS3 allows one to vary damping two with a 5 second turn of a lever.
One other side point, rebound damping obviously controls the rate at which the suspension returns to its sagged position. The reason this is usually easier to dial in is the forces the spring exudes on the damper are consistent during the rebound stroke. EG, there is no way to "speed up" or "slow down" the way the spring is forcing the shock back to the top of the stroke (well, relatively anyway - we wont get into the crazy finite details of air springs....yet.)
Hope that helps.
Damping is *speed sensitive*. This means damping controls the input forces depending on the time horizon those forces are applied to the shaft. Put another way, damping (specifically compression) is dependent on the speed of the shaft (not your riding speed). This is why when we apply more damping it does not effect sag, but it may effect how long it takes for that sag to be achieved. There are exceptions to this, as there are position sensitive dampers out there as well - but we will ignore that in this exercise.
A spring is *position sensitive* in that it reacts differently to a set force depending on where it is in its position (how much the spring is compressed). A coil spring is generally linear. Air spring generally progressive, though both can be manipulated. For instance, Exit often uses a progressive coil spring package, and many Fox products can be setup super linear if you set the EVOL chamber up with minimal amount of pressure.
The idea is to have the spring support the chassis and rider, with the appropriate rate to keep make the most effective use of the available travel (and intended goal) whereby damping is the way that travel is controlled. Again, this too is going to be dependent on application and goal.
There are areas where damping can be used to some extent where the spring is falling short or a spring can be used where the damping is falling short, but ideally you have both tuned specifically for the job at hand. Again, this is why I'm such a big fan of air in a skid application (progressive=good, easy to adjust depending on conditions/environment=good). Custom valved QS3 allows one to vary damping two with a 5 second turn of a lever.
One other side point, rebound damping obviously controls the rate at which the suspension returns to its sagged position. The reason this is usually easier to dial in is the forces the spring exudes on the damper are consistent during the rebound stroke. EG, there is no way to "speed up" or "slow down" the way the spring is forcing the shock back to the top of the stroke (well, relatively anyway
- we wont get into the crazy finite details of air springs....yet.)Hope that helps.
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