[jay]

OK, I'm obviously missing something. Can someone explain why the gear ratio changes when the drivers change?? OK, lets say that we are using 22/41 gears, that is a 1.86 ratio to the driveshaft correct? That ratio to the shaft is 1.86 regardless of the drivers right?? So I guess I'm confused about where the change takes place and how it is calculated.

If someone can please explain this to me, I would appreciate it.

Thanks

 

[jay]

I understand that the 9 tooth driver is a smaller diameter than the 10, but where does this play into the gear ratio that is in the chaincase? And how is that ratio calculated??

If a 22/41 is 1.86 on a 9 tooth, that is calulated by dividing the 41 by the 22, correct? There is no other conversion factor, so why is a 22/41 on a 10 tooth 1.68?? What is the conversion factor and why is it not used when calulating ratio on a 9 tooth driver??

 

[jay]

Anybody want to explain this to me?? Come on.

 

[ods dan]

I will try an easy way...
The "gear ratio does not change"

The whole drive ratio does change..

With the 10 tooth driver its like adding taller tires to a truck....yet the gear ratio did not change..
So it will by my calculations change the "whole ratio" by 10/9ths...or 1.111

so if your ratio of 22-41 before was .536 on a std sled----now it is equal to a .595......ratio

I hope this is right and makes sense..

 

[ods dan]

ps....I like that way to figure ratio , just my preferance...

 

[jay]

Makes more sense than anything I've heard so far.

The only thing I don't get is the 10/9ths deal. I mean you can't just use 10 and 9 because that may not be the difference in ratio between the drivers actual diameters??

 

[BobCat]

The easiest way to understand this is to realize that with 9t drivers you are laying down 9 track lugs per turn of the drive shaft. 10t drivers lay down 10 lugs per turn. On flat snow, the lug spacing is 2.52" therefore you travel 22.68" per turn with the 9 tooth and 25.20" with the 10 tooth. Effectively you have "taller" overall gearing with the 10 tooth so the gearbox ratio has to change to compensate.

BobCat

 

[BobCat]

Should have added that trying to think of this in terms of driver diameter is not needed. Just think in terms of how many lugs per turn you are laying down!

BobCat

 

[jay]

BOBCAT,

Thank you. So the ratio IS based on the diameter of the driver, makes sense to me now.