Clutching theory

Sep 15, 2008
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Great thread! I have been researching for quite some time now and it is hard to find a direct answer to a pretty specific question that I always fumble with.

About the team helixes. I always get confused on what all the numbers mean and how they will effect performance. for example, my sled has 56-42-.36
As I understand it (and I could have things a little backwards here) the 56 is the initial angle, the 42 is the finish angle, and the .36 is the percentage of the total that the initial angle holds?? could someone shed some light on this for me? also what effect will changing each of these numbers have on performance?
 

winter brew

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Great thread! I have been researching for quite some time now and it is hard to find a direct answer to a pretty specific question that I always fumble with.

About the team helixes. I always get confused on what all the numbers mean and how they will effect performance. for example, my sled has 56-42-.36
As I understand it (and I could have things a little backwards here) the 56 is the initial angle, the 42 is the finish angle, and the .36 is the percentage of the total that the initial angle holds?? could someone shed some light on this for me? also what effect will changing each of these numbers have on performance?
You have it right. That first angle (56) progresses to the 2nd angle (42) for the first .36 inches of ramp travel....the first is only 56 degrees initially and is progressive to the 42....if that makes sense.
Steeper angles load the engine harder (upshift quicker) but have slower/weaker backshift and less belt squeeze. Opposite with shallower angles.
 

Norway

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secondary

New question: how far up in the secondary can you have your belt? Just the "cooling fins" above the sheave or can you go a bit further?

I ask because I'm messin with a P-85/Bearcat combo. Thought the belt would never see the bottom of the secondary, but I blew a couple of belts last season and when I took it apart for cleaning, the shoulder was smeared black..

RS
 

winter brew

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New question: how far up in the secondary can you have your belt? Just the "cooling fins" above the sheave or can you go a bit further?

I ask because I'm messin with a P-85/Bearcat combo. Thought the belt would never see the bottom of the secondary, but I blew a couple of belts last season and when I took it apart for cleaning, the shoulder was smeared black..

RS
As high as you want (within reason), as the belt will drop lower into the sheaves as soon as the sled moves.
 

Norway

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As high as you want (within reason), as the belt will drop lower into the sheaves as soon as the sled moves.
It's that "within reason" thing I'm asking about ;) Just the cooling ribs or 1/4"??

RS
 
Dec 2, 2001
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Spokane WA
Great thread! I have been researching for quite some time now and it is hard to find a direct answer to a pretty specific question that I always fumble with.

About the team helixes. I always get confused on what all the numbers mean and how they will effect performance. for example, my sled has 56-42-.36
As I understand it (and I could have things a little backwards here) the 56 is the initial angle, the 42 is the finish angle, and the .36 is the percentage of the total that the initial angle holds?? could someone shed some light on this for me? also what effect will changing each of these numbers have on performance?


I know Winterbrew answered your question, but just to add a little tid-bit you can change the .36 (manipulate is probably better) by shim stacking the secondary spring. Adding a shim can do two things for you; 1 it adds pre-load to the spring and 2 it will shorten the distance of the initial angle
 
Dec 2, 2001
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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?


You are probably closer to 2 to 1 than 1 to 1 in this example. If you truly geared to be at 1 to 1 (secondary loaded) the sled would be miserable to drive down the road. Everbody talks about getting closer to that ultra-efficient ratio of 1 to 1, and granted that is the most efficient, but if you look at efficiency charts 2 to 1 is exponentially better than 3 to 1. You could gear for one specific condition but the trade-off isnt worth it imo.
 
Oct 14, 2008
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Help with heel clicker weights

HI,
I just bought a2004 viper mountain with a 159 polaris skid. I am running heel clicker weights and am wanting to know what to run for the higher elevations. Right now on flat land Iowa style 8500 r's at about 70mph. I havent pulled the weights out yet to weigh what grams are currently being run in the shoulder center and tip. Just wondering what would work for the mountains thanks...
 

Ron

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Great thread!

When you think clutching is right then a good test is to check RPM/backshift on different snow surfaces. Run from groomed to deep snow-clutch should backshift quickly, R's return quickly. Try a hill in deep snow, let off throttle get back on it.
Some put too much emphasis on RPM-just because you are running the right R's doesn't mean you are getting max performance. We have two other tests when we think we are close-first is to increase weight in the primary until it pulls down R's. At that point you know you can't pull more weight(without other changes). For most conditions more weight in the primary means the clutching is less affected by altitude and snow conditions-less finicky. Second is to test against another sled and in different conditions so you can see actual results of changes..."Seat of Pants" can lie.
There are some good points on mass location vs shift charactoristics/RPM. All mass has some affect on the shift. If you think of the bolt as the fulcrum point (pivot point) it's easier to visualize why the location of mass affects shift charactoristic's based on location. The further the mass from the fulcrum, the more force exerted at higher R's. The closer the mass to the fulcrum point the less force exerted at higher R's. You can make some significant changes in clutching simply by repositioning mass in weights. SkiDoo's TRA has a fixed, yet movable ramp so it's a different animal.

Edit: One more thought....the driven "torque converter" can run into extreme conditions beyond it's ability to function properly without clutching changes. In our area, the Rockies, we normally have dry powder with some wet heavy snow in the fall and spring. With wet heavy snow you have two factors at play-a lot more "load" from the track and heavy rolling resistance from the chassis. An easy fix is to change the helix angle a couple degrees shallower on a Polaris. I run a custom helix from Carl's that has the two cuts I need. It's an easy change that can be made in the field on the Poo.
 
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papafinger1

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I will be the first to admit that I no absolutely nothing about clutching other than the suggestions given by oem charts and fellow sw'ers. I recently spent 2 very informative hrs with Lon from thunder products discussing gearing, primary clutching, and the torque converter/ secondary. He broke the tuning process down into terms that I was capable of understanding. Many views he has conflict with some here but nonetheless I am able to comprehend the terminology you are all using thus gaining knowledge about clutching theory. Thanks to Lon and all of you I feel I have the ground works set to confidently and successfully clutch my home built turbo. Although this yr will be spent developing a turn key set-up, next yr I will concentrate most of my efforts into clutching. Thanks again and continue to improve my clutching IQ....
 

Spiderman

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Great thread! I want to throw out an example. Lets say your clutches are creating a lot of heat equally. (p85, older team clutch) The sled starts out at 8100 and drops rpms on a long climb down to about 7700. On trail it climbs rpms, 8000 on intial full throttle settles to 7500 at about 40 to eventually climb to about 8000 rpms. So, one change at a time, you would either use less angle on the second angle of helix or use lesser lbs in the secondary spring on the finish top number to give more force on the belt in the secondary? That's assuming everything else is aligned and working properly with new springs, weights, and belt with proper gearing. It also has lots of low end grunt and no trenching.
 
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winter brew

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Great thread! I want to throw out an example. Lets say your clutches are creating a lot of heat equally. (p85, older team clutch) The sled starts out at 8100 and drops rpms on a long climb down to about 7700. On trail it climbs rpms, 8000 on intial full throttle settles to 7500 at about 40 to eventually climb to about 8000 rpms. So, one change at a time, you would either use less angle on the second angle of helix or use lesser lbs in the secondary spring on the finish top number to give more force on the belt in the secondary? That's assuming everything else is aligned and working properly with new springs, weights, and belt with proper gearing. It also has lots of low end grunt and no trenching.
Close.....except you would want MORE secondary spring force to give more belt squeeze/more RPM. Or just drop a litlte primary weight.
 

Spiderman

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I originally thought it would be more force but then I looked at the spreadsheet http://www.snowestonline.com/forum/showthread.php?t=172390 and changed my mind. I still mustn't be reading it correctly. Is the side pressure in the chart the same as sheave pressure against the belt? So my team red black at 140/240 I could change to say to a 160/260 and that would squeeze the belt tighter or would I want to go to the 180/280 to see a definite change? I am hitting my rpm target but it doesn't stay there because of heat (long climb) or not quick enough of backshift.(long flat straightaway on trail) The team uses only compression force while the regular polaris secondary uses torsion to make the compression on the spring somewhat adjustable?
 
Dec 2, 2001
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I originally thought it would be more force but then I looked at the spreadsheet http://www.snowestonline.com/forum/showthread.php?t=172390 and changed my mind. I still mustn't be reading it correctly. Is the side pressure in the chart the same as sheave pressure against the belt? So my team red black at 140/240 I could change to say to a 160/260 and that would squeeze the belt tighter or would I want to go to the 180/280 to see a definite change? I am hitting my rpm target but it doesn't stay there because of heat (long climb) or not quick enough of backshift.(long flat straightaway on trail) The team uses only compression force while the regular polaris secondary uses torsion to make the compression on the spring somewhat adjustable?[/QUOTE]



I am unable to open the chart:confused:,but I will try to answer. You will see a change in rpm anytime you make a change to spring pressure. Keep in mind that with no other changes, reducing helix angle will increase side pressure against the belt and improve backshift.

On the Team vs a Polaris secondary, the Team functions more linear where the button stlye has more resistence. The torsional force helps to overcome this. Somewhat adjustable yes, each hole you tighten the spring, you increase preload which will increase rpm in increments
 

Barrett

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I originally thought it would be more force but then I looked at the spreadsheet http://www.snowestonline.com/forum/showthread.php?t=172390 and changed my mind. I still mustn't be reading it correctly. Is the side pressure in the chart the same as sheave pressure against the belt? So my team red black at 140/240 I could change to say to a 160/260 and that would squeeze the belt tighter or would I want to go to the 180/280 to see a definite change? I am hitting my rpm target but it doesn't stay there because of heat (long climb) or not quick enough of backshift.(long flat straightaway on trail) The team uses only compression force while the regular polaris secondary uses torsion to make the compression on the spring somewhat adjustable?
Heat equals, slippage, and/or alignment problems. I assume you have checked and corrected all alignment problems. after reading you posts I think you could start by going to the 160/260 sec spring, and if that doesnt help then you need less helix angle from start to finish. after you get the heat under control, then work on the flyweight/primary spring to get revs correct. my .02
 

Spiderman

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Thanks for the info. I'll give the higher rate spring a try first. I assume the linear spring and roller design of the team is supposed to have less resistance than one that is torsional also? Also, I see the chart is for the new team tied clutch. Can somebody explain the chart? The end result is the side pressure on the belt. How does that tell you what helix and spring to use? By finding the combination of new helix and spring that produces the same force in the same shift point of your old set up?
 

winter brew

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I originally thought it would be more force but then I looked at the spreadsheet http://www.snowestonline.com/forum/showthread.php?t=172390 and changed my mind. I still mustn't be reading it correctly. Is the side pressure in the chart the same as sheave pressure against the belt? So my team red black at 140/240 I could change to say to a 160/260 and that would squeeze the belt tighter or would I want to go to the 180/280 to see a definite change? I am hitting my rpm target but it doesn't stay there because of heat (long climb) or not quick enough of backshift.(long flat straightaway on trail) The team uses only compression force while the regular polaris secondary uses torsion to make the compression on the spring somewhat adjustable?

What helix angle are you running? What is the "other" angle on your helix?...provided it has two tracks like most TEAM helix's.
If you can go to a shallower angle try that first. You can also try a 140/260 or 160/260 spring but ideally you want to run as little secondary spring as possible and still get adequate backshift...you don't want to go too stiff or you'll get alot of heat and poor upshift.
The helix itself provides the majority of belt pressure .....the spring is mainly a factor at low speeds, diminishes as speed increases.
You may try just dropping a small amount of primary weight or a little more primary spring finish rate. Are both your springs in good condition right now??
 
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