Why such flat helixes

[Anylizer]

If we go back to the 900KK, we were running anywhere from 43 to 53 degree helixes. This was in Mtn. applications. In the Yamaha MM 700 we could run 47+ deg. helixes.

We now have sleds with more power, improved clutch components... yet we are back to running 34-36 deg. helixes.

Even Doo, in the XP's were running 36's... now on the newer E-Tec's the are back to 46+ helixs.

Why??? what has changed that we have to run such shallow Helix's??

Are the mfg's doing this in an attempt to prolong belt life?

Thoughts???

 

[kiliki]

keeps belt temps down and motor load is evened out. more primary weight and a shallower helix = no rpm yo yo and as you listed more HP is more belt heat as the belt is doing more work. some of it has also to do with the face cut on the clutches too as the slop is not the same on all.
I like mine lighter on the primary and steeper on the secondary you get a faster rev and a better back shift but you do have to keep the heat in check.

we wont even go into bigger tracks and belt composites

 

[Anylizer]

Thing is... we are not pulling more weight. The belt technology should have helped with temps... not sure that is the case.

actually KK made about the same power as the PC 800H.O. but the clutching is miles apart. I can understand different power "curves" but similar HP. yet way bigger helix's and still had great belt life, pulling more mass in the primary and steeper helix.

IMO... we have more belt YoYo.. because of the lower gearing that is getting thrown at these things.

Thoughts???

 

[kanedog]

Keep on digging Anylizer. You will find the answer soon. You will be shocked. Most old timers who have been around clutching for more than 20 years know what's up.

 

[Anylizer]

In one conversation, it was suggested that flat helixs' were the result of compression only springs in the secondary (high spring rates). Which was necessary because of the engine reverse... We no longer had a clock twist/ pre-loading of the secondary sheaves.
Well that doesn't fly either... Ski-Doo is still running the same clutch but with steeper angles... and very similar spring rates as in 2008.

Cam arm profiles are the same FOREVER in both Polaris & Cat. Cat throws the same damn primary spring at every model they sell...
And in the M-chassis IIRC the only difference between the 800 & 1000 was cam arm mass... same springs in both clutches, same helix angles...

 

[diamonddave]

Thing is... we are not pulling more weight. The belt technology should have helped with temps... not sure that is the case.

actually KK made about the same power as the PC 800H.O. but the clutching is miles apart. I can understand different power "curves" but similar HP. yet way bigger helix's and still had great belt life, pulling more mass in the primary and steeper helix.

IMO... we have more belt YoYo.. because of the lower gearing that is getting thrown at these things.

Thoughts???

Also running longer and taller lug tracks. This will load the motor much more.

 

[mike_s]

Keep on digging Anylizer. You will find the answer soon. You will be shocked. Most old timers who have been around clutching for more than 20 years know what's up.

Indeed.

The conclusion i have come to is the OE's have forgotten how to clutch their stuff, as evidenced by a stock engine destroying $200+ belts, and big 1500 triples of more than 200 HP living happily an entire season on $40 belts. Trouble is, if any of us chime in our findings, we get brow beat by the guys who "know it all" and, its just not worth the fight.

 

[Dartos]

Keep on digging Anylizer. You will find the answer soon. You will be shocked. Most old timers who have been around clutching for more than 20 years know what's up.

It has been 2 weeks, let's hear (or more appropriately, read) your answer!

I'm ready to be shocked.

 

[Anylizer]

It has also been suggested that the problem stems form a 2 ramp helix (as opposed to the 3 ramp of years gone by) is the culprit. The big 3 mfg. all use a team 2 roller type set-up.
The problem with this theory is that Doo is also using a 2 ramp/roller set-up... and they are finally back to steeper helixs!

 

[Anylizer]

Indeed.

The conclusion i have come to is the OE's have forgotten how to clutch their stuff, as evidenced by a stock engine destroying $200+ belts, and big 1500 triples of more than 200 HP living happily an entire season on $40 belts. Trouble is, if any of us chime in our findings, we get brow beat by the guys who "know it all" and, its just not worth the fight.

I'm not sure they forgot... It's definitely more profitable for them to keep going the way they are!

 

[bailer]

Yup, I had a piped, head, reeds and clutched mm700, 47 helix that I swear had more snap than my xm800 with stock clutching?!?

 

[winter brew]

In the case of newer Doo, they run a shallower helix but a MUCH softer sec spring. Overall result is similar as far as belt side pressure.
We also have to be careful comparing old to new as clutch designs change....helix diameter, where they are measuring the angle and sheave angle all play into what is required for a helix.
Then there is the primary setup. About 7 years ago, the EPA got involved and sleds have to meet emission regulations. In the case of Doo, clutching was a part of meeting those requirements. Lower profile ramps and reverse angle helix to drop rpm and lower sound levels at testing parameters. Made a lot of heat and used a lot of belts. The etec allowed them to get away from this clutching concept and go with more appropriate clutching on mountain sleds.
As a general rule, the bigger tracks and harder belt compounds benefit from a shallower helix or other methods of increasing belt side pressure (within reason).

 

[geo]

It's an E reverse thing. You can fit a old style clutch if you don't want reverse and get back to the good ol days of light side pressure (which helps keep the belt cool when off throttle)

If you want E-reverse you need the notch. The notch takes away any backshift signal from the helix for half the clutch so,,, stiffer spring, especially in the lower ratios.
You can move the side pressure from spring to helix and back for many combos that work under acceleration but in the mountains you can't compromise on backshift too much especially when you need to push more weight to open that spring.
Most of todays sleds are a pretty good compromise now if your clutches stay straight. Full progressive helix`s help a bit too which may be the next step from the OEMS. But that notch still screws up the straight spring set-up.

I tried to tortionalize the Teams (seems to be a lot out there lol) with high hopes. Did the Tied first but,,, the 2 roller system eats itself too fast even down to 12lbs of pull.
So, reverse or no lol, or live with the not too bad set-ups and belts nowadays. They can works well too.

 

[Anylizer]

It's an E reverse thing. You can fit a old style clutch if you don't want reverse and get back to the good ol days of light side pressure (which helps keep the belt cool when off throttle)

If you want E-reverse you need the notch. The notch takes away any backshift signal from the helix for half the clutch so,,, stiffer spring, especially in the lower ratios.
You can move the side pressure from spring to helix and back for many combos that work under acceleration but in the mountains you can't compromise on backshift too much especially when you need to push more weight to open that spring.
Most of todays sleds are a pretty good compromise now if your clutches stay straight. Full progressive helix`s help a bit too which may be the next step from the OEMS. But that notch still screws up the straight spring set-up.

I tried to tortionalize the Teams (seems to be a lot out there lol) with high hopes. Did the Tied first but,,, the 2 roller system eats itself too fast even down to 12lbs of pull.
So, reverse or no lol, or live with the not too bad set-ups and belts nowadays. They can works well too.

I could agree with you IF we had always had encapsulated rollers... but we didn't. Additionally, 2011 ETEC with the same helix design since the advent of the QRS... and it has a 47* helix

 

[geo]

Don't know what your getting at Any?? Maybe I missed some stuff and this a "why is AC still blowing the clutch side of things" thread 'cause the rest aren't that bad and don't run the helix angles you speak of.
Lot's of people change out their stock Cat stuff too.

Maybe you can clarify the point you are trying to present. You bounce between tortional comparisons and compression. 2 different animals especially in primary set-up. Which is the one you would like to discuss?
Another thing confusing me is you need to consider the motor RPM (let alone secondary style) when comparing sleds too. Not just HP.
A King Cat at anywhere from 7200 to 7600 is a poor primary weight comparison to a M8 at 8050 to 8250. Either one can run 75 gr weights and either one can run 68 gr weights, even with different secondary styles. Just depends what you are trying to achieve for feel for you personally but the force produced because of the rpm of each is very different.
There is no one perfect set-up with all the possibilities in clutch components.

First I would like to disagree with you on one point you made. If you run shallow helix and stiff spring, absolutely this set-up requires more weight and it's not because of HP. It's simple physics and there has been many new weight-profile designs to attack this since compression set-ups came out.
Definitely a heat maker set-up and as you pointed out most have gotten away from it.
They're heavy (weights) compared to the past and by past I mean tortional to clairify.

You mentioned something about we never had encapsulated before. Again, tortional didn't need it and the QRS (compression) was not the best initially. It has evolved, like the rest, to a balance between angles and spring rate-static pressure, like most of the rest. It`s a better compromise now that initially when they started to show up because of E-reverse.
If you could run a compression set-up fully encapsulated it would be more effective because the helix would be able to provide it`s feedback at all sec. clutch ratios. The notch takes away the bottom half of this (like many have pointed out) for backshift so spring compromise. The primary weights have to overcome the spring pressure to start the shift so you compromise weight to attack the compromise in spring and the belt takes the abuse lol.

If you don`t use the notch you might as well get back to the more effective way of producing enough side pressure with good torque feedback of the tortional set-up. But, I do think the big tracks would still require some extra squeeze.


I'm sure you have done some playing with this and know the difference in a couple of degrees on the helix and 10 or 20 lbs. on the spring with both systems of secondary. So have many others.

It's really easy to understand, E-reverse changed the style of secondary and this was not for a more effective CVT system. Live with it or get rid of it. The cost is higher belt prices and life with maybe a little less HP transfer but that is debatable too.
As for belt life, before the more expensive ones were around and while tracks were getting longer and deeper I saw plenty of set-ups that ate a few belts a day lol. Even in the good ol`times.
Sled clutching has always been an evolution with the chassis changes and it is no different today. So try to remember facts and not complicate it with apples to oranges comparisons.

 

[Anylizer]

O.K. let me try and clear up some of the "Mud" lol.

While I am "somewhat" directing this at the "Cat" clutching (my current challenge), It is still a general brand discussion. Even a '15 Pro using a (IMO, POS) Team clutch is running a 36* helix.
In my (op) I misstated the XP initial helix angle, I said 36*.... it was 42*. (which is inline with yesteryear, even torsional) But they are now running much steeper angles.(47*) and it works!!!
I do realize that some of this is related to the difference between torsional vs. compression. I can agree that encapsulated rollers would have better input, and the reverse notch effects this(somewhat). But... even when converting to a torsional set-up, only a slight increase in angle will work. So it cant be totally a compression/torsional issue.


Here is what is see.... Lighter sleds, more HP, supposedly better belts(doubtful), and taller/longer tracks.
Track... simple gear change should resolve any issue there, but not a drop from 2.2:1 to 2.6:1 This is causing us to waist the lower 2/3 of the clutch (most efficient, more squeeze) and running a lot in the upper 1/3 (least efficient, less squeeze) Gearing this low, seems to me, causes a lot of "YoYo" in the clutching = belt heat. (lots of rapid upshift/backshift)... and never loading the engine.
HP... more power should easily deal with more aggressive clutching. ie... steeper helixs, aggressive ramp profiles etc. especially with the stupid 2.6:1 gearing.
Lighter chassis... LESS LOAD.

yet the clutching has... IMO gone soft! IMO it is the mfg's band-aid. Htey are too busy cranking out the next failure to spend time on good clutching. sort of a close is good enough approach.


Please understand... I'm not being argumentative. But if there is evidence against the stated opinions... I am going to point out what I see/believe.

 

[kiliki]

more track and taller lugs= more grip and more leverage. you talk about the mm700 and gearing but it all comes down to leverage and the helix slows the lever. the more energy the belt transfers the more work it has to do, the more heat it will build... UNTIL it over powers the grip side IE more track takes more power to make it to the break over of the grip. older sleds less power less grip but when guys build up the triples then the power beat the grip, same for turbos today.

 

[geo]

Any. Poo's don't come geared low or helixed shallow. The Teams may be a POS but they can be made to work and it's what we got.
I'll venture out on a limb lol and say they're p85-Team combo has been leading the way OEM wise for a bit.

Most mountain riding (95%) is still below 1 to 1 and Poo`s benefit by gearing lower than stock (they`re 2.08 to 1) because of that. If most of the riding is below the mountains, they will still get around with stock gearing in the mountains just fine. 'Cause they have there secondary compromise OK.

If you`re project is a PC, good luck but IMO they have suffered enough so,,, that`s all I have to say about that.

 

[kiliki]

Any. Poo's don't come geared low or helixed shallow. The Teams may be a POS but they can be made to work and it's what we got.
I'll venture out on a limb lol and say they're p85-Team combo has been leading the way OEM wise for a bit.

Most mountain riding (95%) is still below 1 to 1 and Poo`s benefit by gearing lower than stock (they`re 2.08 to 1) because of that. If most of the riding is below the mountains, they will still get around with stock gearing in the mountains just fine. 'Cause they have there secondary compromise OK.

If you`re project is a PC, good luck but IMO they have suffered enough so,,, that`s all I have to say about that.

geee thanks for your knowledgeable input. I hope they keep you in the poo section or better yet how did you get out?

 

[geo]

Kiliki, are you working on a Cat too? Sorry, I get it now. This was not a general thread on discussing clutching. More of a frustration thread while working on a PC. Just didn't get that from the OP.

Very very touchy subject and never intended to get into drive train redesign. Sorry for that.