Here is an old IndyDan thread from March 2006 on the Team Secondary which has three things in common with the new QRS two roller post and larger OD helix like the QRS and compression only spring. Its about 50 or 60 pages long and very deep for me, not being a clutch expert but my gut instinct is it has some good clues that may apply to the QRS/TRA.
http://web.archive.org/web/20060317...etalk/messageview.cfm?catid=3&threadid=252783
Here is part of the first page:
"Title: Polaris Industries must be on crack, 900 TEAM Clutch problem solved.
Created On Fri March 10, 2006 10:24 AM
indydan
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Joined: Dec 2001
The 900 sure has some issues, Clutching being just one of the few.
Clutching 101 - Here is a short prospective in clutching that should shed some light from a NON engineer view point. Oval Aaen's clutching book explained for the working man.
Ok, This is some of what is happening to the 900.
Of course we all know that the drive and driven clutches need to work together as much as possible, So to help you understand what is happening with the 900.
Imagin driving down a flat trail at 60 mph, Now that being said, Lets pretend that there is no hood on the sled and no clutch cover so we can watch the clutches.
Now at 60mph the belt is going to be about 1/2 way up the drive clutch, And 1/2 way down into the driven. That being said. Now if you start to go up a small long hill and the throttle speed is held at a constant position, what you will have is a constant force coming from the drive clutch, and the driven clutch will start to feel an increase load on the jackshaft, And being that all drivens are created somewhat equal in the torque sensing area, The driven will start to close and force the belt out or " up " and it will pull on the drive clutch causing the belt to go down in the drive clutch I.E. into a lower gear ratio to help keep the motor in its power curve - SHAZAM!!!!!!! The "CVT" Constant Velocity transmission. This is called backshifting.
Now that was a sample of what happens to the driven clutch when torque is applied from the jackshaft side of the clutch.
Now lets imagin that exact same situation - Driving down the trail at 60 mph watching the clutches..........Now the trail is flat and throttle speed is constant again. Now while watching the clutches at 1/2 shift Punch the throttle wide open, What needs to happen now is the belt needs to instantly start to go up in the drive clutch and down in the driven clutch, This would be called upshifting in both clutches.
Here is where you will learn why belts BREAK sometimes with improper clutch set-ups.
What is happening in the polaris 900 is this, When you punch the throttle and the drive clutch tries to close & upshift,
For a instant the driven clutch is trying to close also, In other words, The driven is trying to backshift when the drive is trying to up shift.. Consiquently stretching and breaking the belt in 1/2.
This is a TEAM clutch issue, And the hard part to understand about this for most tuners that have always been " OK " in the clutch tuning area and are pretty sure they know how to tune a set of clutches because they have worked alot with both Polaris & Cat drivens and understand the difference in helix angle from the Cat to the Polaris driven being about 13 degrees different and will shift about the same.
There is a delicate balance in clutching to get a drive a driven to work together, To get them to upshift fast as possible and yet still backshift as fast as needed based on the type of riding you do.
So in short the problem is, Due to the PERK factor and the love of Electric reverse we are going to be using the TEAM for some time.
The TEAM clutches helix diameter requires that you run much steeper angles then one might think - Example in a 900 Polaris
1st Track - 66-44-42-ER .46
2nd Track - 70-46-42-ER .46
These are the angles that need to be run, Flatland or Mountains it doesn't seem to matter. Most of the time 66-44 .46 will work in almsot all polaris sleds with the TEAM driven.
Black red spring is a good starting spring. TEAM has many springs you can play with.
This should get you closer then you may have ever been with your TEAM Clutch and help you understand what is going on with belt problems.
Backcountry
Senior Member
baD-MAX
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Joined: Oct 2002
Why is the driven trying to backshift for an instant when it should be upshifting? I'm totally confused! Which in my case is pretty easy to do.
baD-MAX
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Joined: Oct 2002
Why is this a TEAM clutch issue?
indydan
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Joined: Dec 2001
You wingnut Max.
I guess I should have explained alittle deeper.
The Helix angles are to flat in most TEAM clutches, And the driven trying to backshift before it upshifts is a common thing, The shallower the angle & the bigger the motor the more violent the action, This is why it surfaced in the 900, The 900 and aplly far more force to the driven.
The reason its more of a TEAM issue is because the diameter of the helix is greater,and the helix angle has to be steeper then most would think, Thats why I say a team issue, If you used any other driven with to shallow of a helix the same thing would happen.
Max are you with me now???
JesseJames
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I have a question. What does the diameter of the helix have to do with the angle of the helix? What is the relationship between the two??
Marvs660
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Gonna be another good read.
Now which aftermarket secondary was it that claims for a quick backshifting once throttle was applied? So with that secondary wouldn't one be breaking belts also?
And I see what you mean about the larger diameter of the helix needing to be steeper as it brings the helix more towards the center of the secondary instead of closer to the shaft right?
Gotta love PERC though once you've been in situations where it can be used. But it is practically useless in deep powder.
indydan
Senior Member
Posts: 4287
Joined: Dec 2001
Quote
Originally posted by: JesseJames
I have a question. What does the diameter of the helix have to do with the angle of the helix? What is the relationship between the two??
Quote
What is the relationship between the two?
Mechanical Advantage.
Its really no different then opening the clutch cover of your sled and grabbing the O.D. of your driven, and turning it with one had and the sled moves across the floor. Now grab in closer on the helix hub and try to turn it, Then take the clutch off and try to move the sled by grabbing the jackshaft and turning it.
Now imagin you are the jackshaft and think about how the leverage factor changes has the roller or helix trac moves out from the center-line of the jackshaft.
indydan
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Joined: Dec 2001
Fri March 10, 2006 12:11 PM
Quote
Originally posted by: Marvs660
And I see what you mean about the larger diameter of the helix needing to be steeper as it brings the helix more towards the center of the secondary instead of closer to the shaft right?
BINGO!!!!!!!!
Exactly Marv.
Sorry Marv I posted before I saw your post.
truckracer7
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Posts: 151
Joined: Nov 2005
thanks for the info and making it easier for the rest of us to understand
it makes sense now the way you explained it
Marvs660
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geo
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Joined: Dec 2004
How come you never watched the clutches with a downhill after the flat at a constant throttle? That may have shown you the resistance to upshift that the heavy spring you are using may be the reason for belt breakage.
Clutching 101: Part load upshift is mostly controlled by spring pressure, full load upshift is mostly controlled by helix angle. If you use a spring that doesn't upshift at part load then it will effect full load too much and cause your clutches to run less than ideal. The backshift of the old twist the spring style clutch was initiated by the twist load pulling with the helix angle and the new encapsulated roller design is signaled by side pressure release (loaded spring) working AGAINST the helix angle on the backshift side. That is why most mountian setups use a heavy spring, to counter the fact that they have too shallow an angle on the helix and help the backshift.
The new style clutches are not there because of reverse, they are there because they work better. They upshift easier but not necessarily back shift easier. That is the balance the tuner has to find and because they react to load at the track better they need to be set up with less weight and in the front to make them open. This will allow you to use steeper helix angles (which backshift easier in this style secondary clutch) and softer springs. The light front setup backshifts easier too.
In the old discussion of heavy wieght- light wieght front set up, it was always said that you need wieght in the front to load the motor and open the back clutch. Well, now the back clutch opens easier and loads the motor through quicker gearing change. The higher side load pressure of the new style secondary keeps squeeze on the belt and increases as the sheaves open and get smaller in diameter. The old style secondary had little side pressure, compared to the new style, and used the helix angle more to provide belt squeeze (resistance to opening, not good). Adding wieght to the new style clutch only requires a stiffer spring and robs hp.
It seems to me, Dan, you need to finish watching the clutches at part throttle and start to let the back clutch open because I very much doubt that 2 degrees in a helix is the difference between a belt snapping or not. Heat and delamanation can do that. Geo.