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Discussion Starter · #1 ·
Ok, first off the only reason I am asking this is for room I put a 1.5 track on my 03 F7 firecat and believe I need the room to be able to stud anyhow can these be changed without changing anything else ?? what is the gearing differance ?? and what gears would I use to offset the drivers ?? I am allready clutched and I am going to use the lower brackets off a 05 thanks Mike
 

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Discussion Starter · #3 ·
yes to lower the skid. this is why I am doing this so I can stud a 1.5 track and have a margin of safty between the stud and the front exchanger
 

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Just looked into my artic cat service manual and they have theoretical numbers in there between the difference between the spockets. So with out knowing what you gear ratio is I am just going to give you the threoretical numbers for 19/40 gears for 8000 rpm to show you the difference between the drivers. With a 10 tooth and running 19/40 sprockets you should be hitting 101.7 mph at 8000 rpm. 9 tooth running 19/40 sprockets motor turning at 8000 rpm theoretically will hit 81.7 mph. According to the chart you would have to run 22/37 with the 9 tooth to get into the same ball park in mph for the 10 tooth running with 19/40. Number in the book say the mph at 8000 rpm would be 101.8 mph for 22/37 sprockets with 9 tooth driver. What do the 03's run for sprockets and I can look up what it says you should be running for sprockets in the chain case on a 10 tooth to a 9 tooth conversion to theoretically hit the same top speed.
Also from going from a 10 tooth 2.52 pitch drivers to 9 tooth 2.52 pitch drivers you will gain about 1/2 of an inch extra clearance to the front cooler. You might have to mess a little bit with your clutching. The smaller drivers will also create a sharper rolling radius which will rob a small amount of horsepower. Kind of like all the claims of big wheel kits on the rear axle. Large rolling radius will be easier to bend the track around compared to a smaller radius such as smaller drivers. Longer paddles will also add some resistance. The track acts as a big fan, longer lugs catch more air as the track spins. You will also have some added rotating mass of a heavier track and longer heavier studs so your top speed probably won't be what it was before. Hence possibly some clutch tuning with going to a different track. I did a track swap of my 900 1m and went with different drivers with a different pitch and less teeth for clearance issues also. Went from a 151 x 2 x 15 to a 150 x 2.5 x 16. It definately put more load on the motor due to better traction and more weight and resistance. It was bearable with out some fine tuning of the clutchs but I like experimenting to see what works and what doesn't and I am close to having the clutchs by the end of last season dialed in. I did a gear change but can't remember off hand what I did but my difference in driver diameter wasn't as big as yours. I gained close to an extra 1/4 inch on the front cooler.
 

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Originally posted by mtnsnopro@Aug 30 2005, 10:24 PM
Just looked into my artic cat service manual and they have theoretical numbers in there between the difference between the spockets.  So with out knowing what you gear ratio is I am just going to give you the threoretical numbers for 19/40 gears for 8000 rpm to show you the difference between the drivers.  With a 10 tooth and running 19/40 sprockets you should be hitting 101.7 mph at 8000 rpm.  9 tooth running 19/40 sprockets motor turning at 8000 rpm theoretically will hit 81.7 mph.  According to the chart you would have to run 22/37 with the 9 tooth to get into the same ball park in mph for the 10 tooth running with 19/40.  Number in the book say the mph at 8000 rpm would be 101.8 mph for 22/37 sprockets with 9 tooth driver.  What do the 03's run for sprockets and I can look up what it says you should be running for sprockets in the chain case on a 10 tooth to a 9 tooth conversion to theoretically hit the same top speed. 
Also from going from a 10 tooth 2.52 pitch drivers to 9 tooth 2.52 pitch drivers you will gain about 1/2 of an inch extra clearance to the front cooler.  You might have to mess a little bit with your clutching.  The smaller drivers will also create a sharper rolling radius which will rob a small amount of horsepower.  Kind of like all the claims of big wheel kits on the rear axle.  Large rolling radius will be easier to bend the track around compared to a smaller radius such as smaller drivers.  Longer paddles will also add some resistance.  The track acts as a big fan, longer lugs catch more air as the track spins.  You will also have some added rotating mass of a heavier track and longer heavier studs so your top speed probably won't be what it was before. Hence possibly some clutch tuning with going to a different track.  I did a track swap of my 900 1m and went with different drivers with a different pitch and less teeth for clearance issues also.  Went from a 151 x 2 x 15 to a 150 x 2.5 x 16.  It definately put more load on the motor due to better traction and more weight and resistance.  It was bearable with out some fine tuning of the clutchs but I like experimenting to see what works and what doesn't and I am close to having the clutchs by the end of last season dialed in.  I did a gear change but can't remember off hand what I did but my difference in driver diameter wasn't as big as yours.  I gained close to an extra 1/4 inch on the front cooler.
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just dont forget that a taller track will act like a bigger drive wheel, especially on hard pack, when figuring gear ratios use this formula and youll be close;

gearing= engine speed x sprocket pitch diameter
-----------------------------------------------
shift ratio x mph x 336


engine speed= rpm's
sprocket pitch diameter= sprocket diameter+ track thickness
for a shift ratio just use 1 it will get you close
for mph use what you want to acheive realisticly

for an example= 8000rpm x 10toothsprockets(roughly 7.75inches) =62000
- ----------------------------------------------------- ------
1(shift ratio) x105mph(just a number i picked)x336= 35280

so 62000 divided by 35280=1.7573696, so with the above combination i used you would have a ratio of 1.75gearing OVERALL not just whats in the chaincase. if you use this it will get you closer than just figuring chaincase gearing cause it takes into account the extra hieght of the track lugs that your changing. if you get me the info on your sled ill figure it for you if you want. :div20:

ps you can figure your chaincase gearing by dividing your bottom sprocket with the top sprocket,,, example you have 25/40, 40 divided by 25=1.6 gear ratio in the chaincase.
 

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Go to Brown's Leisure World's site and look up the gearing on a 2004 F7 Snowpro. You will have very close to the same combination. 9 tooth drivers, skid mounted under the running board and a 1.25 track available on that sled. www.brownsleisureworld.com.
 

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Track thickness has nothing to do with speed calculations. It just seems like it fits into real world numbers.

The theory has proven to be scientifically wrong.
 

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Originally posted by joetech@Aug 31 2005, 08:57 AM
Track thickness has nothing to do with speed calculations. It just seems like it fits into real world numbers.

The theory has proven to be scientifically wrong.
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BULL, and it does have something to do with gearing. obviously if you have a sprocket thats 7.75 inches and a track that has a profile of 1.5 inches that gears it up.

its like going from a low profile tire to a 35" mud tire, there is a differance
 

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The bull has been heavily debated in the past and i am sorry but track thickness is no comparison to a wheel.

there is no constant radius with a track

If you put a 6-inch thick track on your sled and rotated the drivers at a constant speed and then switched to a 1-inch track the speeds would be indentical.

If you don't believe me talk to a physics professor.
 

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Originally posted by joetech@Aug 31 2005, 09:36 AM
The bull has been heavily debated in the past and i am sorry but track thickness is no comparison to a wheel.

there is no constant radius with a track

If you put a 6-inch thick track on your sled and rotated the drivers at a constant speed and then switched to a 1-inch track the speeds would be indentical.

If you don't believe me talk to a physics professor.
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whatever dude, sit back and read what you said it makes no sense and im getting my info from someone (olav aaen) that knows a dam site more than you. maybe speeds would be identical but gearing would change which is what were talking about. and yes you did hit the nail on the head, a CONSTANT speed of the drive wheels but if you switch to a thicker track you force the clutches to change RATIO, i dont care about speed
 

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Originally posted by joetech@Aug 31 2005, 09:57 AM
Track thickness has nothing to do with speed calculations. It just seems like it fits into real world numbers.

The theory has proven to be scientifically wrong.
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[/quote]
You are right. The track is a conveyor not a wheel. The drivers are the
wheels. Their diameter affects the gearing ratio. Distance covered per
revolution. Like a tire....
 

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Originally posted by user2@Aug 31 2005, 10:08 AM
You are right. The track is a conveyor not a wheel. The drivers are the
wheels. Their diameter affects the gearing ratio. Distance covered per
revolution. Like a tire....
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you guys just dont get it, the part between the driver and the ground effectively adds to the overall diameter of the driver, duh. your trying to tell me if you take a 6" wheel and wrap something 1" thick around it it doesnt add to the diameter of the wheel? which in essence has an effect on overall gear RATIO, NOT SPEED for the umteenth time. a 1.5 inch track on top of 7.75" drivers is going to be geared HIGHER than a .75" track on 7.75"drivers. HEEEELLLLOOOOO!!!!
 

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Last i checked snowmobiles don't ride on a wheel. The drive wheel is mounted up in the chassis. The linear velocity of the machine is determined by the *length* of track put onto the ground within a given time. Note i said length not circumference. The length of track is the same regardless of thickness.


Of course gearing and clutching will affect the determination of a sleds velocity, that fact is not in debate. They are all factors except for track thickness.

Sorry but the velocity of a wheel is determined by the circumference and the velocity of a track is determined by a linear dimension.
 

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Originally posted by joetech@Aug 31 2005, 11:00 AM
Last i checked snowmobiles don't ride on a wheel. The drive wheel is mounted up in the chassis. The linear velocity of the machine is determined by the *length* of track put onto the ground within a given time. Note i said length not circumference. The length of track is the same regardless of thickness.
Of course gearing and clutching will affect the determination of a sleds velocity, that fact is not in debate. They are all factors except for track thickness.

Sorry but the velocity of a wheel is determined by the circumference and the velocity of a track is determined by a linear dimension.
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sorry but the thickness of the track over the wheel adds to the overall size of that wheel which in turn affects gear ratio, im done cant show everyone the light i guess.
 

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Originally posted by machz1@Aug 31 2005, 11:06 AM
sorry but the thickness of the track over the wheel adds to the overall size of that wheel which in turn affects gear ratio, im done cant show everyone the light i guess.
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okay come on guys! even i understand this, and remmember us teens dont know a thing :div20:
 

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okay take a 16" wheel. put a 1 inch thick tire on it and rotate it at 10mph. then take that same 16" wheel and rotate it at 10mph with a 3 inch thick tire on it. which is ganna roll faster? this is virtually the same thing as the driver and track is simulating. this is the best way i thought to explain it.
 

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Think about it this way.

I agree that the track thickness will affect the velocity of the outside edge of the track as it is bent around the drive wheel, if you could get an instantaneous measurement on the drive wheel. The velocity at the point of track to driver contact is a slower velocity. You have 2 different velocities because we are talking about a circle. At the point of contact on the ground the velocities are the same from the inside surface to the outside surface. This is a linear velocity that is equal to the angular velocity measured at the driver to track contact point.

If you have your 7.5 inch driver rotate 1 turn you can only put down say 3 lugs of the track. If you increase the thickness you still only can put down say 3 lugs.

That is a fact!!!!
 

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Originally posted by jordan123@Aug 31 2005, 11:15 AM
okay take a 16" wheel. put a 1 inch thick tire on it and rotate it at 10mph. then take that same 16" wheel and rotate it at 10mph with a 3 inch thick tire on it. which is ganna roll faster? this is virtually the same thing as the driver and track is simulating. this is the best way i thought to explain it.
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They are gonna roll the same speed from your example... 10mph. The one with the 3" thick tire will however roll farther.
 
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