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Shred4Ever
Well-known member
Why only 6 Tooth drivers ??? c/w 6.5" dia & 19/45...
Help me understand....
Help me understand....
Why 6 Tooth Drivers???
- Thread starter Shred4Ever
- Start date
a 3.5" pitch, 6-tooth driver is the same diameter as a 7-tooth 3" pitch driver.
The new track is 3.5"-pitch.
The new track is 3.5"-pitch.
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This is the one thing that I'm not a big fan of...
At the moment.
At the moment.
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Shred4Ever
Well-known member
Okay... But 6.5" dia... That's small.. Nope not a fan yet.
Can you get a 3" track on an 7-tooth, 3.5"-pitch driver into the tunnel???
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Yes, if the bulkhead is the same as the T-3. The diameter difference between the 8 tooth 3" driver and 7 tooth 3.5" driver is a little over .15". The 3.5 being bigger. I have 8 tooth 3" in my T-3 with at least .5" clearance
Robbie, do you feel .5 " sufficient clearance on this chassis sincere question?
With the cooler configuration, there will not be the sheet of ice build-up on the roof and close-out of the tunnel that the other brands have...
I do recognize and highly value actual clearance in use compared to clearance of a warm/dry tunnel.
I know for a fact... that on the Polaris ProRmk/AssaultRmk's... that the sheet of ice/snow often decreases the clearance to zero... this is not even close to an ideal situation...The ProRide Standard RMK's and the AXYS Assaults have a front "bulkehead cooler"... but only at the front lower... unlike the Rush which wraps to the roof of the tunnel.
IMO... the Doo (and the AXYS-mtn sleds with front cooler & Cats to a certain degree) is a much better system to reduce parasitic drag and transfer a higher percentage of power to the track when that ice forms... and the track is 'slapping' at the ice/snow buildup.
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With the cooler configuration, there will not be the sheet of ice build-up on the roof and close-out of the tunnel that the other brands have...
I do recognize and highly value actual clearance in use compared to clearance of a warm/dry tunnel.
I know for a fact... that on the Polaris ProRmk/AssaultRmk's... that the sheet of ice/snow often decreases the clearance to zero... this is not even close to an ideal situation...The ProRide Standard RMK's and the AXYS Assaults have a front "bulkehead cooler"... but only at the front lower... unlike the Rush which wraps to the roof of the tunnel.
IMO... the Doo (and the AXYS-mtn sleds with front cooler & Cats to a certain degree) is a much better system to reduce parasitic drag and transfer a higher percentage of power to the track when that ice forms... and the track is 'slapping' at the ice/snow buildup.
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Is .5” enough? I guess that depends on your personal preference. When I started snowmobiling, 9 tooth 2.52” pitch drivers were the norm. They had a diameter of about 7.2”. Since tracks don’t touch 180 degrees of a driver, a 9 tooth driver will drive off 3-4 rows of rubber drive lugs on the track. Back then, we had about 130 horse and 136X1.75” tracks. Today 7 tooth 3” pitch seem to be the norm(6.68” diameter). We now have 3 rows of drive lugs engaged at any one time. Because of spacing, a 6 tooth 3.5” driver will have 2-3 teeth engaged and its’ diameter is 6.5”.
Track lengths have increased to 162, paddles have grown to 3” and the horse power has increased to 160+. Those internal drive lugs are increasingly taking a bigger and bigger load. What is the limit of these loads, before the track belt bends and the rubber drive lugs start to tip? Therefore the track slips. I’m sure that Ski Doo has researched this and theie drivers have performed to their expectations. I wonder about turbo’d sleds however.
It wasn’t too many years ago that a popular performance upgrade was to change out the stock 6.25” rear idlers and change them to 8” for rolling resistance reasons. Today all the manufacturers offer rear idlers that are close to 8”. The drivers however are going the other direction.
Most sleds come stock with about .5” clearance from the factory. Personally, I go with a large driver for rolling resistance and track approach angle reasons. Everything seems to be a compromise.
Track lengths have increased to 162, paddles have grown to 3” and the horse power has increased to 160+. Those internal drive lugs are increasingly taking a bigger and bigger load. What is the limit of these loads, before the track belt bends and the rubber drive lugs start to tip? Therefore the track slips. I’m sure that Ski Doo has researched this and theie drivers have performed to their expectations. I wonder about turbo’d sleds however.
It wasn’t too many years ago that a popular performance upgrade was to change out the stock 6.25” rear idlers and change them to 8” for rolling resistance reasons. Today all the manufacturers offer rear idlers that are close to 8”. The drivers however are going the other direction.
Most sleds come stock with about .5” clearance from the factory. Personally, I go with a large driver for rolling resistance and track approach angle reasons. Everything seems to be a compromise.
3.5" pitch, 6t driver=21" circumference (6.68" diameter)--SkiDoo's new intro
3.0" pitch, 7t driver=21" circumference (6.68" diameter)--what many doing with the 3" tracks
3.0" pitch, 8t driver= 24" circumference (7.64" diameter)
2.86" pitch, 7t driver=20.02" circumference (6.37" diameter)
2.86" pitch, 8t driver= 22.88" circumference (7.28" diameter)--stock for many sleds now.
2.52" pitch, 8t driver=20.16 circumference (6.42" diameter)
2.52" pitch, 9t driver=22.68" circumference (7.22" diameter)--old standard for stock sleds
2.52" pitch, 10t driver= 25.2" circumference (8.02" diameter)--what many used with the drop and roll chaincase back in the day...and had to gear down.
3.0" pitch, 7t driver=21" circumference (6.68" diameter)--what many doing with the 3" tracks
3.0" pitch, 8t driver= 24" circumference (7.64" diameter)
2.86" pitch, 7t driver=20.02" circumference (6.37" diameter)
2.86" pitch, 8t driver= 22.88" circumference (7.28" diameter)--stock for many sleds now.
2.52" pitch, 8t driver=20.16 circumference (6.42" diameter)
2.52" pitch, 9t driver=22.68" circumference (7.22" diameter)--old standard for stock sleds
2.52" pitch, 10t driver= 25.2" circumference (8.02" diameter)--what many used with the drop and roll chaincase back in the day...and had to gear down.
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I find the skidoo marketing angle of their new cooler design an absolute farce. There is no way in He(double hockey sticks) that their bath tub design cools better than a properly designed finned (internally and externally) extrusion. I'd liken it to the current Polaris bath tub style extrusions.
Thermodynamically it is far more beneficial to have a lot of surface area both internally and externally to transfer the the heat out and away from the transfer medium (in this case Glycol / water). With the current Polaris and the new Skidoo G4 cooler design; it is like a bath tub which is a volume style system and as such retains far more heat than it can dissipate.
With a proper High surface area to volume ratio cooler, the manufactures could lighten the wet weight significantly by reducing the volume of transfer medium necessary.
Note: I have not seen a G4 in person or a cut away of the cooler. If the top and bottom sheets of the cooler are no more than 1/16" apart then I may have eat a little crow here. But from the drawing the cooler is far thicker than 1/16" just from the radius lines where the bottom sheet is embossed. Also guessing Skidoo opted for Lords (or similar) adhesive to sandwich the cooler sheets together, as it makes the most sense.
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Loudhandle, thanks for your input and insight on this matter, I see what your concerns are regarding this design. Right or wrong, it's much easier to read your posts without the "Ski Don't " slander we're all used to hearing, or we'll call it constructive criticism.
I guess we'll find out if this is a good design or not next season, I'd like to think they've researched plenty 
before they changed to this system.My observation after riding a few different sleds with various driver diameters.
I think smaller drivers help A LOT with maneuverability and ease of changing direction.
The big wheel vs small wheel inertia thing.
Had a few sleds with big drivers and after swapping to smaller the handling changed quite a bit for the better.
In a straight line and high trackspeed the larger drivers obviously are better.
Also with nearly identical sleds except one had a drop and roll the d&r sled handled much worse. In the tight trees and such.
We noticed zero difference in performance with the one sled having an inch more clearance.
I think smaller drivers help A LOT with maneuverability and ease of changing direction.
The big wheel vs small wheel inertia thing.
Had a few sleds with big drivers and after swapping to smaller the handling changed quite a bit for the better.
In a straight line and high trackspeed the larger drivers obviously are better.
Also with nearly identical sleds except one had a drop and roll the d&r sled handled much worse. In the tight trees and such.
We noticed zero difference in performance with the one sled having an inch more clearance.
Sincere questions.
What sleds was this observation made on?
Was there still 1" more clearance during riding, or was the track 'slapping' at ice/snow buildup at the tunnel-closeoff on both?
No tunnel clearance when a big chunk of ice just forms on the front. This is a pic of my 3". Wonder if the 2.6 just does the same thing.
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IMO...unless you can keep the tunnel close-off, and remainder of the tunnel for that matter, clear of ice/snow from forming...Extra clearance does not add any performance because that clearance goes away in use.
Close-off coolers and tunnel roof coolers, like the one used on the sled featured in this forum for Gen4-REV's... help to keep the dry/warm clearance a reality on wet/cold mountains.
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Close-off coolers and tunnel roof coolers, like the one used on the sled featured in this forum for Gen4-REV's... help to keep the dry/warm clearance a reality on wet/cold mountains.
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2011 pro rmk 163.
ice build up in the tunnel close off hasn't been that extreme ^^^^ at least that i have seen. I assume in certain snow conditions it gets that way.
Just really no difference in performance. Over 3 years of riding together almost every time we went (brothers)
That looks like the under side of my 2012 PRO RMK 800 163 after every ride while I owned it.
