L
LRD
Well-known member
If you are switching track pitches and using Avid drivers (mine are smaller)this calculator is invaluable.
http://www.turboaddictionparts.com/catalog/snowmobilecalculator.html
The turbo addiction mph/gearing calculator is the best one I have ever found.
Heres why, it will do any pitch, which means it will do any goofy sized driver diameter.
Example: The 8 tooth 2.86 drivers off of my 08 TNT mtn mod are 7.170" OD which is 22.525" in circumference divided by 8 teeth = a Real Pitch of 2.815
Here is a great calculator for circumference of a circle
http://www.athropoli...pup/c-circ2.htm
At .85 overdrive and 8000 rpm with 19/45 gears = 84.75 mph
So with the claimed 2.86 pitch at .85 overdrive and 8000 rpm with 19/45 gears = 86.10 mph
Now thats not a heck of a difference but I switched to Avid 7 tooth 3" pitch drivers last winter and they are 6.25" OD, which is .250 smaller than injection molded so I couldn't directly match my old gearing with any of the gearing calculators or formulas and had to just take a guess. That 6.25" = 19.635" circumference = 7 is only 2.805 pitch, not 3.0" so it make for a 3.5 mph difference plus the 1.35 mph of the doo driver difference so it really messes up the gearing.
I wanted to be geared somewhat lower because I went from a 1.75 paddle to 2.25 paddle so just left it at 19/45.
Wow was I surprised when I ran the numbers old and new with the actual diameter of the drivers and tooth count that I was geared 12 MPH slower at full overdrive compared to the old 8 tooth drivers. There was no way of figuring this out before. A 22/45 is just under the old 8 tooth with 19/45 while 23/45 is a bit over the old 19/45 with 8 tooth for max mph.
It sure cleared some things up on my recent trip to WY, why I had a heck of time trying to hang onto my sled and had to re-tune clutching and suspension to try and keep the front end down enough to steer. From about 0 to 10 mph was putting down power like a 365 lb sled with 200 HP. Part of my hanging on problem was this was my first mtn ride since wrecking my left hand a year and half ago. Figure maybe up to about 1/3 of the grip I used to have on the left hand.
Awesome calculator!!!
Good Luck
http://www.turboaddictionparts.com/catalog/snowmobilecalculator.html
The turbo addiction mph/gearing calculator is the best one I have ever found.
Heres why, it will do any pitch, which means it will do any goofy sized driver diameter.
Example: The 8 tooth 2.86 drivers off of my 08 TNT mtn mod are 7.170" OD which is 22.525" in circumference divided by 8 teeth = a Real Pitch of 2.815
Here is a great calculator for circumference of a circle
http://www.athropoli...pup/c-circ2.htm
At .85 overdrive and 8000 rpm with 19/45 gears = 84.75 mph
So with the claimed 2.86 pitch at .85 overdrive and 8000 rpm with 19/45 gears = 86.10 mph
Now thats not a heck of a difference but I switched to Avid 7 tooth 3" pitch drivers last winter and they are 6.25" OD, which is .250 smaller than injection molded so I couldn't directly match my old gearing with any of the gearing calculators or formulas and had to just take a guess. That 6.25" = 19.635" circumference = 7 is only 2.805 pitch, not 3.0" so it make for a 3.5 mph difference plus the 1.35 mph of the doo driver difference so it really messes up the gearing.
I wanted to be geared somewhat lower because I went from a 1.75 paddle to 2.25 paddle so just left it at 19/45.
Wow was I surprised when I ran the numbers old and new with the actual diameter of the drivers and tooth count that I was geared 12 MPH slower at full overdrive compared to the old 8 tooth drivers. There was no way of figuring this out before. A 22/45 is just under the old 8 tooth with 19/45 while 23/45 is a bit over the old 19/45 with 8 tooth for max mph.
It sure cleared some things up on my recent trip to WY, why I had a heck of time trying to hang onto my sled and had to re-tune clutching and suspension to try and keep the front end down enough to steer. From about 0 to 10 mph was putting down power like a 365 lb sled with 200 HP. Part of my hanging on problem was this was my first mtn ride since wrecking my left hand a year and half ago. Figure maybe up to about 1/3 of the grip I used to have on the left hand.
Awesome calculator!!!
Good Luck
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