F-12/F-14 with High Speed gears

Seth Boyer · Sep 3, 2014

I bought a 7 mph 3rd gear rear end for my F-12 I'm building. I'm curious how many of you guys own any of the variations of the faster gear sets or know of people who do.
I also have a Heisler gear box to go along with it. Hope to surprise a lot of people when I get this thing up and running.

Oldiron29 · Sep 4, 2014

Seth, I do have an F-14 electric start that has K or L code rear end I can"t remember wicth one I will have to go look. Just mounted a two way plow on it, Hoping 1st gear isn"t to fast for plowing. We will have to see. The F-12 you are working on is that the wide front? oldiron29

Seth Boyer · Sep 4, 2014

Oldiron29, I also have a K code rear. If I remember right that one has the same 1st gear speed as the standard F transmission. Then it has a 4 mph 2nd and 7 mph 3rd. I'll know for sure soon as I'll take my GPS with me on a ride.

I wonder if I can convince some people at a show my 1937 F-12 had factory installed GPS??? Haha

I have the F-12 that had the homemade wide front build from a 31 Ford model A front axle. Basically I took grandpas tractor and for now I have the motor, front end and frame rails, using all the gas tank mounts off that tractor so the serial numbers match. On that tractor I'm using 40" round spoke rears and a NF with round spokes. I love that look and I'm making the tractor as light as possible.

I'm keeping the wide front along with the rear steel and I plan yo build another tractor using all it.

James Williams · Sep 4, 2014

I also have a 7 mph F12,it was my first F12,I guess I lucked out

jimmy

rusticredacres · Sep 4, 2014

Seth, IH had several combos on F12, F14 tractors. I think about 6 or 7 different combos. I will look and can report back as I have the list. There was a 10 mph 3rd gear and all other were 7 mph and lower. I will let you know for further discussion.

Seth Boyer · Sep 4, 2014

Did any of you guys who had the higher speed trans also have a Heisler overdrive unit? What size of tires were you running and what modifications had been done to the motor? Did the tractor have plenty of power traveling in 3rd gear at those higher speeds?

I'm asking all this because I hope when I'm done with mine I plan to use it driving in some tractor cruises.

rusticredacres · Sep 7, 2014

Letter code stamped on left rear of transmission housing on machined boss and here is gear combos
F
1st 2.27 2nd 2.98 3rd 3.84 reverse 2.28
K
1st 2.27 2nd 3.81 3rd 6.60 reverse 2.28
L
1st 3.25 2nd 5.50 3rd 9.58 reverse 3.25
M
1st 2.27 2nd 2.98 3rd 6.30 reverse 2.28
X
1st 3.25 2nd 4.25 3rd 5.50 reverse 3.25
Z
1st 3.25 2nd 4.25 3rd 9.58 reverse 3.25

These are mph speeds for rowcrop F12,F14 tractors

F-12/F-14 with High Speed gears

Seth Boyer

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Oldiron29

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Seth Boyer

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James Williams

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rusticredacres

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Seth Boyer

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rusticredacres

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