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Discussion Starter · #1 ·
As I have stated before this is my first SXS, but I have been clutching snowmobiles for 20 years and understand clutching. Took my wildcat to the dunes this weekend and did some testing on fairly steep sand hill.
If you understand clutching you can’t have the primary and secondary clutch set up for two different gears. I have this problem on my turbo snowmobile the primary weights are very heavy to handle the horse power at 12lbs of boost (250hp). This really affects my bottom end until the boost kicks in to push the weights out. Makes it a little harder to ride in the trees, but up steep hills its unbelievable.
On the wildcat we have a low gear and the clutch seems to be set up to hold RPM in the low gear. In low gear up a steep sand hill my wildcat would hold 6700-7000RPM and climb higher than in high gear. In the high gear up the same hill the RPM would quickly pull down to 5500-6000 rpm, way out of the power band.
The problem with the low gear is you can’t get the speed up before the hill and you can’t shift on the fly from high to low. It’s impossible to set up the clutch for both gears and hit peak RPM’s. If the clutch is setup for the high gear then you will over rev in low gear.
If you only wanted to run in high gear only lighter primary clutch weights should fix the problem and hold at peak RPM. I like the low gear for climbing non sand hills and I plan on doing some rock crawling this summer.
The wildcat clutching had to be setup for the low gearing peak RPM and thus the high gearing will always have lower RPM when back shifting (can’t have both).
The other option would be to change the high gear to something between high and low gear (not sure if gears can be changed). Overall top speed would be reduced but it would climb better. In snowmobile hill climbing world sled have lower gears than lake race sleds. They don’t go 150mph but they will climb a wicked steep hill at 70mph track speed.
 

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I often wondered if the gearing was some of the problem. We have machined our sheave and can now go 45ish in low gear. I rarely find myself needing high gear now.
 

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yes i have also done alot of testing on the factory clutches. with our stage 1, 2, and 3 work done, which gains 18% gear reduction on take-off, plus holds you in a midrange gear longer, and gives you a little more top speed, we saw 44-45 in low range, with such a hard launch i could definitely feel wet clutch slip. this minimal amount of work, will give you tons more low end, smoother take-off, and awesome throttle control due to the lower starting gear ratio and make handling obstacles and technical terrain so much easier to navigate with the lower gearing at take-off and slow speeds. since we change the angles of the fixed plate in our stage 2, it holds your clutch in its lower and midrange gearing longer giving you tons better throttle response in the midrange, and helps the clutch backshift faster with the increased ramp angles of the roller plate. since we also make the clutch close up more at full shift with the stages 1-3, we gained nearly 8mph in low range. giving you right at 45mph in low gives you so much more gearing and allows you to run longer stretches without having to upshift into high gear. hill climbs should be a breeze with 40+mph in low range capability.

its not necessarily the gearing of the trans you are trying to overcome with the wildcat, it is more or less the inability to backshift under loads. in high range you can get the clutches in such a high gear ratio so fast, that the clutch is stuck in (hypothetically) 4th gear when you hit a hill, and cant backshift into 3rd gear under throttle so your engine bogs down from lack of gearing and lack of power. in low range, you run almost exactly the same shiftout RPM, but the trans has such a shorter gearing in low, that the clutches almost cant stick themselves in too high of a gear for the engine to pull.

i know alot of you have never seen a cat clutch setup workin in action, because arctic cat clutches need the outer cover on in order to support the outer clutch shaft. i cut a cover up once with a sight window to see the clutches in action. the arctic cat centrifugal roller clutch setup upshifts super fast. in low range, you stab the throttle, and the belt is at the top of the primary by about 18mph which is only about 2 seconds under power and the rest of your mph in low range comes from engine RPM climbing. in high range the clutch is maxed out by 40-43mph meaning the belt is at the top of the primary rather quickly. after the clutch is at the top of the primary you then gain engine RPM to continue accelerating. once you are above this "full shift" speed, your clutch is at such a high gear ratio it is easy for the engine to get bogged down when the secondary cant backshift you into a lower gear.

running a spring (sprung) style primary puts you into the regular world of clutching, where a clutch upshifts more slowly, and will backshift itself when you get under loads. if you watch a sprung style primary setup run, these clutch setups will hold their shiftout RPM longer, and take longer for the clutch to reach "full shift" meaning the clutch stays at a lower gear ratio longer thru its range of acceleration, and since the primary has a spring to help itself backshift, it will quickly backshift itself into a lower gear as you experience loads.

the stock primary will not backshift itself under loads, you must let out of the throttle in order for the secondary to pull the primary back to a lower gear. this is why our stage 2 setup, works so well on arctic cats. by changing the ramp angles of the fixed plate that the rollers roll against, we can change how quickly the clutch upshifts and hold the clutches in a lower gear ratio longer. with our stage 2 done to the stock wildcat last weekend, we prolonged the "full shift" of the wildcat from a stock 40-43mph, to nearly 55-57mph. this means the clutches hold the shiftout RPM longer and hold you into a lower gear ratio longer giving you more power at the blip of the throttle in your midrange and more power on a long pull. also since we change the ramp angles of the fixed plate, it also helps the rollers roll back quicker and easier, which in turn equates to a faster backshift.
 

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Adam, great explanation of how your stage 1-3 works, but can you explain the difference in the stage 5 mod you did for my clutches? How does it differ from the stage 1-3?
 

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Adam, would your recommendation be to do the stage 1-3, take it all the way 5, or wait till the WCD is sorted out and stable. I am not aiming for extreme performance, just satisfaction and reliability.Thanks
 

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Discussion Starter · #8 ·
Adam, I agree a snowmobile style primary clutch would work better than the wet clutch. You are missing the point on the post, it’s impossible to clutch the wildcat correctly for both high and low gears. You can clutch correctly for high or low gear but not both at peak RPM’s.
A good fix would be to slightly increase low gear (0-45 mph) then reduce primary weights to hit peak RPM’s. The reduced primary weight would also help the high gear performance since RPM would increase. Low gear would be used for climbing hills, high gear for running down the road. Not sure if gears can be changed on the wildcat.
 

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the stage 1-3 is more along the lines of beginner stages to the wildcat.

stage 1 - gives 18-20% gear reduction in the clutch for awesome low end, awesome throttle response, and slower cruising speeds for serious technical riding ability

stage 2 - holds the clutch in its midrange longer, slowing the rate of upshift in the clutch by changing the angles of the fixed plate, and changing the rate at which the rollers roll up the fixed plate. increasing the angle of the fixed plate also helps the clutch backshift faster making it more snappy since the increased ramp angles force the rollers back down the ramps quicker

stage 3 and 4 are usually done together and lighten the primary clutch in order to save reciprocating weight, and since i thin the clutch out further in the stage 4, i always machine the sleeve down to a shorter length to put the clutches back in their proper alignment.

stage 5 is where we machine the secondary to allow the belt to ride lower in the secondary giving you an overall taller gear ratio easier.

stage 5+ is where we lighten the secondary clutch up in order to save weight and allow the secondary to rev faster which helps the machine accelerate quicker.


i'll be perfectly honest, the stage 1-3 SERIOUSLY impressed me this weekend on tennesses machine. full reports to come very soon
 

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I will second that.
 
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