Been talking with Duane, it sometimes takes a long time to get a new helix so tunning takes a while
Clutching theory
- Thread starter devilrmk
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Josh Zieske
Josh Zieske
Josh,
Please read the first post in this thread again before posting. What you are doing is not what we want on this thread.
Just Q mattymac. My performance source, with multiple drag- and sno-x wins to his credit, always complain that customers call, ask for a clutch kit and when he ask if anything has been done to the sled they say; no, just geared it down. His reply is always; "no, I dont have a clutch kit for you if you've geared it down".
RS
Secondary explained, or...?
After I read Aaens book and saw how the secondary work with the helix, I always thought of it as threads on a bolt. The helix angle compared to a fine/coarse thread.
This way I see the balance as the engine trying to "un-screw" the nut from the bolt (opening) while the resistance from the driveshaft/track being the oposite force trying to screw in the bolt into the nut, ie closing the secondary.
does this make any sense?
RS
After I read Aaens book and saw how the secondary work with the helix, I always thought of it as threads on a bolt. The helix angle compared to a fine/coarse thread.
This way I see the balance as the engine trying to "un-screw" the nut from the bolt (opening) while the resistance from the driveshaft/track being the oposite force trying to screw in the bolt into the nut, ie closing the secondary.
does this make any sense?
RS
Lower gearing typically DROPS some RPM....and taller gearing GAINS RPM.
When I am gathering info for a clutch setup, gearing is ALWAYS a factor.....what style rider are they, where do they ride, track lengh and more importantly track weight...engine mods etc...
I am a fan of fairly low gearing for the mountains (but not TOO low) because lower gears will put the belt higher in the primary at any given speed. This gives more belt/sheave contact area which makes for less slippage (less heat) and also gets us closer to a 1:1 ratio...which is where a CVT system is most efficient.
There are other with different theories on clutching/gearing but this has always worked well for me.
When I am gathering info for a clutch setup, gearing is ALWAYS a factor.....what style rider are they, where do they ride, track lengh and more importantly track weight...engine mods etc...
I am a fan of fairly low gearing for the mountains (but not TOO low) because lower gears will put the belt higher in the primary at any given speed. This gives more belt/sheave contact area which makes for less slippage (less heat) and also gets us closer to a 1:1 ratio...which is where a CVT system is most efficient.
There are other with different theories on clutching/gearing but this has always worked well for me.
Define "too low" please. Is it possible, like are there actual gear combinations out there to get "too low" ? Just curious what some problems could be.
Thanks. I too am a fan of low gearing. I could care less about trail ride speeds..
Too low and things become TOO sensitive. Too low and your belt moves up/down the sheaves more with speed changes....more movement up and down the sheaves means more potential for heat so there is a fine balance in there somewhere....2.00-2.35 seems to be where most mountain guys end up depending on track length, power, riding style etc..
S
shortstop20
Well-known member
I agree with Winter Brew.
Olav Aaen has some good comments about gearing in his book. He says to shoot for a gear ratio that will put your clutches at a 1:1 ratio where you do the most of your riding. Since the clutches are most efficient at this ratio, it only makes sense to use that ratio as much as possible.
I did this on my Pro-X and it worked quite well.
Olav Aaen has some good comments about gearing in his book. He says to shoot for a gear ratio that will put your clutches at a 1:1 ratio where you do the most of your riding. Since the clutches are most efficient at this ratio, it only makes sense to use that ratio as much as possible.
I did this on my Pro-X and it worked quite well.
J
Jeff K
Well-known member
Some good (free) reading here: http://www.gates.com/index.cfm?location_id=3850
Belt deflection ?
Side Belt Clearence ?
I can always tell when I jump on a sled if the belt deflection is jacked up. Starting in a higher gear ratio induces bog, poor belt life and throttle response.
Great thread keep her going
Side Belt Clearence ?
I can always tell when I jump on a sled if the belt deflection is jacked up. Starting in a higher gear ratio induces bog, poor belt life and throttle response.
Great thread keep her going
Belt deflection is very important. To much or to little, same result. Your "missing out on gears", so to speak.
To much deflection is caused by 3 things: wrong belt (to long/narrow), C-C distance wrong or incorrect setting/shimming of the secondary.
Ti little is the same, except to wide or to short instead of long/narrow.
To much and your belts creeps way up on your primary before being caught by both sheaves. To little and your belt never reaches the top of your secondary clutch.
It all takes away from both starting and full shift ratio.
RS
To much deflection is caused by 3 things: wrong belt (to long/narrow), C-C distance wrong or incorrect setting/shimming of the secondary.
Ti little is the same, except to wide or to short instead of long/narrow.
To much and your belts creeps way up on your primary before being caught by both sheaves. To little and your belt never reaches the top of your secondary clutch.
It all takes away from both starting and full shift ratio.
RS
Ramble bamble...blah blah blah. SOMEONE JUST GIVE THE PERFECT SETUP FOR ALL CONDITIONS ALREADY!!! Nah just kiddin! AWsome thread. Personally I like a sled that upshifts like a drag racer myself. They just seems snappier and funner to ride. (of course that also describes why I think Cats are so boring to ride) excluding insanely boosted ones. Not sure if they feel so lazy cuz of the motor design or the clutching.
Love the way my Xp holz clutching upshifts. It's a blast when you wheelie up and your track zings up to 60 mph its almost out of control feeling. But that makes my point. Clutching is so much rider preferance and riding style. My setup can be very sensitive to changing snow conditions b/c it is very upshift oriented but I'm Ok with it b/c I understand it and know what to change to make it work better.
I think Winterbrew said it best so far in my opinion. Gearing for the kind of riding you want to do so as to optimize CVT ratio is key.
It is a fine balance between not enough side pressure on the belt (ie. slippage and heat) and to much belt pressure so the primary is fighting to open the secondary while trying to upshift.
All in all I think clutching is one of the funner parts of sledding. It never gets boring trying to perfect the almost unperfectable.
Great thread.
Love the way my Xp holz clutching upshifts. It's a blast when you wheelie up and your track zings up to 60 mph its almost out of control feeling. But that makes my point. Clutching is so much rider preferance and riding style. My setup can be very sensitive to changing snow conditions b/c it is very upshift oriented but I'm Ok with it b/c I understand it and know what to change to make it work better.
I think Winterbrew said it best so far in my opinion. Gearing for the kind of riding you want to do so as to optimize CVT ratio is key.
It is a fine balance between not enough side pressure on the belt (ie. slippage and heat) and to much belt pressure so the primary is fighting to open the secondary while trying to upshift.
All in all I think clutching is one of the funner parts of sledding. It never gets boring trying to perfect the almost unperfectable.
Great thread.
L
LRD
Well-known member
The most amazing thing I ever learned about clutching happened by accident back in 05. Was wining to a friend about how doggone much harder sidehilling my new 05 summit 550 fan was compared to the old Phazer mtns. He suggested putting in a high rate primary spring (130/280) HUH? So I buy about five springs 100/260, 100/280, 130/280, 130.320, 160/280 etc. The one that worked amazing was the 130/280 and 100/280 for the wifey. Works for sidehilling because when the front end starts washing out downhill, just a little burp of the throttle gets max R's and breaks the track loose and rear of sled washes out and is level with front end again.
BUT the other thing it does is the High Rate (short spring, fat wire) with lower lbs at engagement allows clutch weights to generate more belt squeeze so the sled will literally tractor along through the powder at 5 to 12 mph without breaking the track loose. This is if you set up with lower engagement
RPM.
Fixes that track everybody was complaining about a few years ago.
The 100/280 on the wifes sled is because she doesn't get stuck anymore and I can ride more. It will tractor along at near 15 mph before it tips over and snaps to shift RPM.
Takes a little experimenting to get the right spring that you like but well worth it. Kind of like having two different clutching setups or ratios in one clutch setup, low and high. The 160/280 on my 385 lb 629 fan mod was nuts, burp throttle at 15 mph and skis were two feet in air, where stock style springs couldn't get front off the snow to save your life or jump a log. One of my complaints on that sled (no weight transfer) turns out to be the primary spring not the rear suspension, sure surprised me. Never ran that spring in the powder as I felt it was to aggressive.
I currently use a high rate on my 380 lb 08 mod mtn TNT and friends use it on 800R's, old mod MXZ big bore triple etc., it just flat works!!!! Makes for a fun to ride sled!!!
These high rate style springs are just the opposite of a lot of doo stock springs over the years, the ones that look like you could put them on a front shock in a pinch cause they are so long!!!
Good Luck
PS Going back to our first trips to the Mtns in late 80's with short track Phazers would have been a whole lot more fun with high rate (lower engagement rpm) primary springs instead of the factory higher engagement rpm springs for high altitude. Wouldn't have been trenching near as much. Factory theory was make up for lower HP at engagement with more R's at engagement mine now is do it with lower gears, max track speed in powder isn't much over 50 mph with anything except turbo's anyhow.
BUT the other thing it does is the High Rate (short spring, fat wire) with lower lbs at engagement allows clutch weights to generate more belt squeeze so the sled will literally tractor along through the powder at 5 to 12 mph without breaking the track loose. This is if you set up with lower engagement
RPM.
Fixes that track everybody was complaining about a few years ago.
The 100/280 on the wifes sled is because she doesn't get stuck anymore and I can ride more. It will tractor along at near 15 mph before it tips over and snaps to shift RPM.
Takes a little experimenting to get the right spring that you like but well worth it. Kind of like having two different clutching setups or ratios in one clutch setup, low and high. The 160/280 on my 385 lb 629 fan mod was nuts, burp throttle at 15 mph and skis were two feet in air, where stock style springs couldn't get front off the snow to save your life or jump a log. One of my complaints on that sled (no weight transfer) turns out to be the primary spring not the rear suspension, sure surprised me. Never ran that spring in the powder as I felt it was to aggressive.
I currently use a high rate on my 380 lb 08 mod mtn TNT and friends use it on 800R's, old mod MXZ big bore triple etc., it just flat works!!!! Makes for a fun to ride sled!!!
These high rate style springs are just the opposite of a lot of doo stock springs over the years, the ones that look like you could put them on a front shock in a pinch cause they are so long!!!
Good Luck
PS Going back to our first trips to the Mtns in late 80's with short track Phazers would have been a whole lot more fun with high rate (lower engagement rpm) primary springs instead of the factory higher engagement rpm springs for high altitude. Wouldn't have been trenching near as much. Factory theory was make up for lower HP at engagement with more R's at engagement mine now is do it with lower gears, max track speed in powder isn't much over 50 mph with anything except turbo's anyhow.
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D
drop the hammer
Member
Another comment on gearing lower. Not only does it put the belt up higher in primary, it also puts you up further along the helix profile, so if it's a progressive cut, your on a different angle now which will have a similar effect as changing helix and very little bit...possibly at a lower angle depending on the helix profile of course. Also on primary clutch your rollers will be further along the ramp face and also at different angle.
Sounds good to me to be as close to 1:1 as possible when in the hill climbing (for me as a mtn rider). I also like the sounds of running lighter pin weight when gearing down, since this would give even better backshifting....I guess one has to balance the cost of these changes to the benefit as changing top gear is relatively cheap, but bottom gear and chain gets spendy. Most guys i talk to get the most performance gain out of a clutch kit, then the gearing is more tuning/tweaking type of stuff at an extra expense....but some of us just can't leave well enough alone.
Sounds good to me to be as close to 1:1 as possible when in the hill climbing (for me as a mtn rider). I also like the sounds of running lighter pin weight when gearing down, since this would give even better backshifting....I guess one has to balance the cost of these changes to the benefit as changing top gear is relatively cheap, but bottom gear and chain gets spendy. Most guys i talk to get the most performance gain out of a clutch kit, then the gearing is more tuning/tweaking type of stuff at an extra expense....but some of us just can't leave well enough alone.
D
drop the hammer
Member
Does anyone know at 50 mph on gearing of 21/49 how close am i to 1:1 shift? stock drivers XP 163. What gearing would get me to 1:1 at 50 mph? I don't care about top speed or lack of speed. In theory that should be the most efficient, correct? But now with my stock gearing on 3 back to back hard long pulls in 3 feet of snow, my clutches are just warm and I can hold them as long as I want comfortably (I use them to warm my hands, i'm such a puss). So why should I regear (other than to experiment)? Doesn't sound like I'm slipping belt regardless if I'm not at 1:1....something to discuss. Would 1:1 be better than what I have?
