Clutching theory

Spiderman

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Dec 1, 2007
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Mn
Hey brew, been riding yet? I have the 54-38.36 and the springs were new last year. That's what I was looking for that the helix provides most of the belt pressure and the spring is in more effect at low rpms. I'm stlill learning in the clutching department. I think I am in the shallowest angle finishing angle but I'll check that. My weights are 10-58 with cpi twins and head on an 01 800 so it should be able to pull them, but we have been at 10,000 ft alot, so maybe I'll have to change them
 

Eli

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Jul 10, 2002
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Omak, WA
On gearing, the lower you are geared the less secondary side pressure is needed due to the decreased load on the secondary.

I believe most sleds could work more efficiently with less spring in both the front and rear clutches. It seems like we are in a snowball effect with clutching...heavier spring needing more weight needing more spring needing more weight, more secondary spring needing more primary weight to pull it open needing more primary spring to offset the weight....and on and on. I personally run a very light setup and have even seen a light primary setup/team secondary on a mostly stock dragon work at least as well as the stock weights. Big weights with big springs don't necessarily "grip" a belt better than light/light setup. I hope I am not off base on this thread.:)

Has anyone converted their sleds to a lighter setup?
 
Nov 27, 2007
401
55
28
Lake Tapps, Wa
So how would you answer this question in theory. On the flats sled shifts out fast up to peak say 8000 rpm, but settles down to 7300 and will not gain from there. On a hill in the trees (on and off throttle) it will be responsive but will fade and eventually bog out. On a straight hill climb it will act like on the flats but will not hit peak in powder only in harder snow. Track speed is decnet on a hill, 40mph for only 7300 rpms. This is on an m7 by the way. Am I wrong in assuming that there is too much spring for the cam angle in the secondary not allowing it to fully shift out?
Another question being can you use a steeper cam angle to overcome a stiff spring?
 
Dec 2, 2001
1,175
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Spokane WA
So how would you answer this question in theory. On the flats sled shifts out fast up to peak say 8000 rpm, but settles down to 7300 and will not gain from there. On a hill in the trees (on and off throttle) it will be responsive but will fade and eventually bog out. On a straight hill climb it will act like on the flats but will not hit peak in powder only in harder snow. Track speed is decnet on a hill, 40mph for only 7300 rpms. This is on an m7 by the way. Am I wrong in assuming that there is too much spring for the cam angle in the secondary not allowing it to fully shift out?
Another question being can you use a steeper cam angle to overcome a stiff spring?



Sounds like too much helix and or spring pressure.

On the second question, the steeper the angle the less side pressure. You dont want to use one to try and compensate for the other. Together the two need to match the side pressure requirements of the belt
 

Clarke_67

Well-known member
Dec 2, 2007
2,894
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Gardiner Montana
I have a TSS-04 clutch in my IQR 800. It has a rattle when you shake the clutch in the air and it has TERRIBLE backshift all of the sudden. I am going to assume that my ramps are wore out or a broken spring. Also, when i take the belt of useing the team tool, the clutch only closes half way? I guess i will swap it out for my older team clutch for now but i realy want to figure out how to get this TSS-04 clutch to work the way it should.

So my question is, i have a 56-38 ramp... What charectoristics should it have as far as backshift? To me, i would rather have better backshift than an explosive sled.
 

Thunder101

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Feb 7, 2008
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One thing not mentioned much yet is cam profile- steeper ramps creating stronger or harder shifts. flatter angles making for a slower smoother feeling shift. Dr spring can effect shift force also, # of lb per inch if a Dr spring has say a 140- 260 vs 140-320 this will also effect speed of shift .

Ive read Aaens book 10-15 times years ago and it is a great book for the can.lol. you cant read it to many times.
Ive clutched all my sleds Ive owned and have had good luck and enjoy it.

Some steps on how to start to clutch your sled. -btw I dont know it all or the 1/2 of it but that heading will help me get some good feed back.lol
-constructive criticism please. :)
I ussally throw weight at it till the desired shift RPM is right -to light of weight and over rev- to heavy and slow to pull or cant pull the desired rpm.,dr spring for engagement with a reasonable rate and tune "play" with the secodary for back shift and no slip & cool clutches.Im a bit guilty of going with to staight of a helix. lol. Still learning
What Ive came across on my presant sled is it does not over rev so its hard (for me ) to know or figure out what is the right cam weight should be . as an example I went fron 68gr, which should have been to light, to 75gr weights of simalar profiles, All shifted at 7950-8000 rpm w/ same dr spring. back shift was bad w/75gr so went to 73.5 and tightened up sec and now its ok but still a little slow on the backshift. I think-beleive there is such a thing as to much belt preasure when it comes to the secodary. But how to know when is to much.??

spiderman thx for posting that link to teams spreadsheet. very interesting Im shocked at how little belt preasure was effected buy helix angle ??? It made no sence to me, great.:eek:

I look forward to hearing others means of clutching.:beer;
 

snopro27

New member
Nov 11, 2008
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AWESOME POST!! Im learning alot but i have one problem. I can get to 8000 rpms and hold it, but my belt and clutches are hotter then h*ll. any advice would be great!
 

Ron

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Dec 4, 2006
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You need to provide a little more info about what you ride and elevation. One place to start is to start it with cold clutches run it hard and then stop to see which one is hottest. That's likely the place to start, the hot one indicates belt slip. If both are equally hot you aren't very close. Unfortunately R's are not "all there is to it". You can vary parts and still see little change in R's.
Edit: Oops lost my focus this is a thread on theory not to get into user issues, sorry!
 
Last edited:
Dec 5, 2001
347
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back country
So how would you answer this question in theory. On the flats sled shifts out fast up to peak say 8000 rpm, but settles down to 7300 and will not gain from there. On a hill in the trees (on and off throttle) it will be responsive but will fade and eventually bog out. On a straight hill climb it will act like on the flats but will not hit peak in powder only in harder snow. Track speed is decnet on a hill, 40mph for only 7300 rpms. This is on an m7 by the way. Am I wrong in assuming that there is too much spring for the cam angle in the secondary not allowing it to fully shift out?
Another question being can you use a steeper cam angle to overcome a stiff spring?
Sounds like a stock M7 with the stock white spring...maybe 44/40 helix? You can compensate by adding preload to that white spring, but it will only be a bandaid for that trackspeed, and will limit your top end. The problem is no backshift. You have too much helix, not enough secondary force at start of shift, too much at the end, and a secondary with a tendancy to bind due to friction. Try a shift assist to help backshift, an AC orange, or better yet goodwin blue, if you can find it, with a straight 36-38 deg. helix. This will help your backshift with more force initially, without limiting upshift due to too much force at full shift.

Decent trackspeed at 7300 rpm tells you that 700 likes to be loaded hard. Keep doing that. You should, however, get it up closer to 77-7800. With the right secondary setup, you'll pull 45mph trackspeed.

John
 

lancelarue

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Nov 29, 2007
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Valdez, Alaska
Clutching basics

You need to provide a little more info about what you ride and elevation. One place to start is to start it with cold clutches run it hard and then stop to see which one is hottest. That's likely the place to start, the hot one indicates belt slip. If both are equally hot you aren't very close. Unfortunately R's are not "all there is to it". You can vary parts and still see little change in R's.
Edit: Oops lost my focus this is a thread on theory not to get into user issues, sorry!
Gear for your speed you run at. ( this is assuming you want a goodclimbing sled)

Clutch secondary to the load you're pulling.( track weight,size,rider weight, SNOW CONDITIONS etc.)

Clutch
primary for target rpm / and to match secondary. Belt spinning in primary - raise finish on spring, add weight. Belt spinning in secondary - drop end rate on spring, drop weight to get rpm.
It's all about "balance" between the clutches AFTER you gear AND find the correct helix/spring to pull the load!!!!!!!!!
 

lancelarue

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what should one do. the sled goes up to the desired rpm and then steadly loses rpms. Basically the sled goes to 8200 rpms than settle down around 7600 rpms.

Should i got to a shallower helix?
Sled?
Rider weight ?
gearing?
track size?
Altitude?
Current set-up?
A few questions to start !
 
Nov 27, 2007
401
55
28
Lake Tapps, Wa
Sounds like a stock M7 with the stock white spring...maybe 44/40 helix? You can compensate by adding preload to that white spring, but it will only be a bandaid for that trackspeed, and will limit your top end. The problem is no backshift. You have too much helix, not enough secondary force at start of shift, too much at the end, and a secondary with a tendancy to bind due to friction. Try a shift assist to help backshift, an AC orange, or better yet goodwin blue, if you can find it, with a straight 36-38 deg. helix. This will help your backshift with more force initially, without limiting upshift due to too much force at full shift.

Decent trackspeed at 7300 rpm tells you that 700 likes to be loaded hard. Keep doing that. You should, however, get it up closer to 77-7800. With the right secondary setup, you'll pull 45mph trackspeed.

John
Yes m7 with rkt head and slp twins, lookin for 8100rpm but can't get it. Secondary has staright 36 and a team black orange 180/280 and shifit assist. Primary was set up with a slp black pink 120/340 spring and 66g dakota weights which have a steeper profile. My theory is that the shallow helix and stiff secondary spring under the slightest load could not upshift fast enough to keep up with the different profile weights. Without a load on the track I can get up around 7800 sometimes 8000 and it rips there but as soon as the track gets loaded rpms drop fast and get alot of belt heat, I can smell it pretty quick. So now I have cutler adjustables to put in and am loading up a 10.4 to put in the secondary set up with a new style 36 and cat orange with shift assist. Hope I'm working in the right direction.
 

Barrett

Member
Feb 11, 2008
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MB
what should one do. the sled goes up to the desired rpm and then steadly loses rpms. Basically the sled goes to 8200 rpms than settle down around 7600 rpms.

Should i got to a shallower helix?
I would first check to see if the clutches are hot which would indicate slippage. then:
if they are nice and cool(meaning no slippage problem), I would lighten the tips of the flyweights about 1.5-2grams.
if clutches hot (meaning slippage - its obviously slipping where the revs are higher)I would install a sec spring with stiffer start ,and re-test to see where rpms end up. you will likely need to adjust flyweights to correct running revs, but you willneed to test test test.:)
my .02
 

440dart

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Jan 5, 2008
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montana
iam very new to the clutching game. the biggest problem i have is understanding what effects what. lets say my helix is a 64-40-.46 "i like to refer the helix as like a manual trans in a car"

iam running the above helix mentioned with a lighter spring then stock i was going the wrong way with my clutching last year. this year iam going to try a 58-38-.36 with a stiffer spring but i had a guy recomend to try a 58-38-.36 what iam i gaining by going from a .46 to a .36 iam thinking by going to the .36 it will shift up faster and backshift faster if thats the case why dont more people go with a .36 instead of .46
 
Dec 2, 2001
1,175
87
48
49
Spokane WA
iam very new to the clutching game. the biggest problem i have is understanding what effects what. lets say my helix is a 64-40-.46 "i like to refer the helix as like a manual trans in a car"

iam running the above helix mentioned with a lighter spring then stock i was going the wrong way with my clutching last year. this year iam going to try a 58-38-.36 with a stiffer spring but i had a guy recomend to try a 58-38-.36 what iam i gaining by going from a .46 to a .36 iam thinking by going to the .36 it will shift up faster and backshift faster if thats the case why dont more people go with a .36 instead of .46


The .36 or .46 refers the the distance in inches of the first angle. So the .36 will shift through the 58* angle and into the 36* sooner than the .46
 
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