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Stock gearing on a F7 is 22/41. AC claims to change gears to 20/39 for 5000+ ft. How much does this really change your gear ratio since when gearing down, both upper and lower gears are 2 teeth less than the stock gearing?? I don't really understand how the end result of this gear change would be all that benifical...... can someone explain?? Thanks!
-John
 

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22/41 is a 1.86 ratio, 20/39 is 1.95. The top end is lower but the acceleration is superior. I geared mine down and still have not lost an impromptu drag race. The lower gearing helps keep the belt and clutches cooler in extreme operating conditions. Not sure exactly how but it does work to prolong belt life. Hope this helps.
 

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Originally posted by JLeosnow@Jan 7 2003, 08:03 PM
Stock gearing on a F7 is 22/41.  AC claims to change gears to 20/39 for 5000+ ft.  How much does this really change your gear ratio since when gearing down, both upper and lower gears are 2 teeth less than the stock gearing??  I don't really understand how the end result of this gear change would be all that benifical...... can someone explain??  Thanks!
-John
As the earlier post said, you're moving from a 1.86 to 1.95. It effectively lowers the starting ratio which is helpful to prolong belt wear by keeping slippage to a minimum while stopping/starting and pulling though deep snow.

Here's why:

When riding at elevation the motor losses power(3% per 1000ft). This has to be compensated with lighter weights. Lighter weights also produce less belt "squeeze". Less squeeze=more slippage. Slippage=heat. Heat=burned belts. Burned belts=$$$

So in effect, the sled makes less power, lighter weights produce less engagement pressure on the belt, and to make matters worse, the sled has to auger through deep snow. No wonder why flatlanders burn up belts in the steep and deep. Gear down!!
 

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Discussion Starter #5
Ok, what about this scenario.... just change the stock top sprocket of 22 teeth to a 21 tooth and stay with the stock lower sprocket of 41..... The final ratio would be 1.95, the same ratio as a 20 tooth top and 39 tooth bottom??

What is the purpose of changing BOTH gears when you can simply change just 1 (the top) to achieve the same final ratio?? Thanks.
-John
 

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John, I just got back from west yellowstone and I optioned to just put in the 60 gram weights. A little doggy out of the hole but ran fine.I mannaged to beet a rmk 800 by 6-7 sled links at the airport (the guy lived in Idaho and was pissed). Powder riding was ausome stayed at goldenwest motel and the owner took us to cabin creek where we rode 18 miles off the trail (5 feet of powder) I got stuck many times but was amazed I could go vertical with the f7> I actually has to much power for this type of riding.(you start sinking let off on the throttle and the sled would raise back up on the snow) My only gripes with the f7 was the oil bottle let the oil level down to half and was riding hard (had to wait at itersections and was bored) looking at my oil line and where it comes out was a 6 inch air bubble. brought it bach to the dealer in yellowstone and he told me it was a bad design and dont let the oil level drop that far try to keep oil level full. 540 miles and ya this thing is ausome!!
 

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In the steep and deep you want to get to full power in a short distance since the fast track spin is floating you in the powder. Top end loss is not as much an issue as is quick acceleration.

Kevin
 

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Arcticmannf7 did you gain much more speed in 660' over stock gear, like to know was setting up for 660'........thanks
 

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Do you run studs, how much speed did you gain, what about a 21-41 would that have more pull out of the hole cause of the bigger gears or the same.......thanks
 

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No studs, went 20/39 15 wide because the chain is stronger and I already had the gears. We always ran 19/43 or 19/40 for 500 ft grass drags in our ZR's. The 10 tooth driver changes things a little though. Hope this helps.
 
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