Gear Ratios

[MJPetersen]

Maybe try this idea that I have. If you get the rolling circumference of the rice tires (front and rear) and put that in the form of a ratio that is your constant. Then whatever tires you choose for the rear you should be able to figure out the size that you need for the front. Or at least the rolling circumference.

For example Let's say that the rolling cir of the rear tires is 100 inches (I am guessing as my tractor is at church and I am home) and the front is 70 inches. Then our ratio of 100 to 70 or 10:7 that is the front would need to turn 10 times for 7 revolutions of the rear. Say you find a tire for the front that is 75 inches then you would need a rear tire of about 107 inches to keep the same ratio.

To my way of thinking then the most important ration is not the gears (although that would be sufficient), but rather the proper rolling circum ratio front to rear and that is what you need to maintain.

Of course all this may be moot as I know that Hoye and LMTC (and probably others too) have tires and I think conversion kits for these tractors to change to turf tires.

I am thinking out loud for my own use in the future.

What do you think of this idea.

Mike

 

[California]

What do you think of this idea.

I think you are on the right track, but doing this right will require some very careful work.

I looked in the parts manual for my tractor (not that same model) and there were four different transfer case gearsets for four different tire size combinations. Standard Rice Tires, Oversize Rears, Turf, and something else I think.

Given that these units might possibly be cobbled together out of dissimilar parts, I think it is necessary to start by counting the ratio of front revolutions to back revolutions. Maybe jack up one side of the tractor and revolve the front tire in 4x4 while counting revolutions at the rear.

Then calculate the tire circumferences needed to overdrive the front by about 3%, and try to find suitable tires to do this.

In this case theory may be irrelevant, due to an unexpected combination of parts. Maybe that's not even the same front axle that should be on that tractor. You don't want to destroy the front axle discovering this.

 

[irwin]

I went through this a while back with my Deere 770. see this..http://www.tractorbynet.com/forums/...0-770-mfwd-ratio-r4.html?highlight=mfwd+ratio

I was able to get the ratio from Deere, but before that I measured the tires on the tractor.

I marked the tire and the ground on very flat ground. Drove til rear wheel did three complete revolutions, measured and divided by three, did the same with front wheels. Divide front rolling diameter into rear and got the difference of the tires on the tractor, then i tried to find tires that would fit with the same ratio. I got close, actually the tires I found were the ones that worked properly after I got the proper ratio from Deere.