Super A Xmission in a 140?

NawlensGator · Jul 16, 2008

Need to rebuild 140 xmission soon. I can buy a complete sup A xmission pretty cheap which would let me rebuild it before swapping (which is a big advantage). I've looked up the parts and see some of the gears are different (the sup A has a higher ratio = faster). But I think if I change the whole unit, case and all, all that matters is that the xmission spline shaft and the right and left differential shafts be the same as the 140's.

The SA xmission shaft is shown 351143R11 vs 351143R21 for the 140, so maybe they are the same size. The diiferential shafts however have completely different numbers, but all have 10 teeth. It goes on to say that the bull gears for both tractors are interchangeable (even though they also have different part numbers). Looks to me like if the bull gears are interchangeable, then the differential shafts from the Sup A should fit.

Can somebody who knows alot more about this than me (ie most people here) explain why a Sup A xmission will or won't work in a 140.

Thanks in advance!

Andrew Z · Jul 16, 2008

If you repaced the whole trans then it would work, it should be geared lower then normal. Due to the Super A's have a higher RPMs and were gear down to mantain the same speed as the A. The 100,130,140 were lower RPMs and were geared higher to be about the same as the Super A was. Howere the 140 is built heavier than the Super A's trans was. but if you dont plan on plowing 100 arces a year i think your good to go.

Andrew

NawlensGator · Jul 16, 2008

Dang Anrdew, that was quick - Thanks. If it's heavier I may buy a used 140 xmission (costs more) to rebuild. Heavier might explain the R11 to R21 difference in the part No. for the xmission shaft.

Now about the gearing -
Sup A 1st & 4th gears have 16 and 37 teeth on the xmission shaft, and 45 and 24 on the pinion shaft.
140 1st & 4th gears have 14 and 37 teeth on the xmission shaft, and 47 and 27 on the pinion shaft.

If I calculate the ratio of pinion shaft rpm to engine rpm I get:

Sup A 1st & 4th = 0.355 and 1.540
140 1st & 4th = 0.298 and 1.37

Unless there is a difference in gear teeth in the differntial/bull gears etc (which I don't think there is), the super A would be 19% faster in 1st and 12% faster in 4th than a 140. One of my 140's is alot slower in 1st than the other, so I'm thinking the other must have 1st gears from a super A. Of course I could be missing something and totally wrong in all of this.

Andrew Z · Jul 16, 2008

Im not sure about the ratios of the 140 im just going on what i know about the 100. I have a 100 that i parted out but i think im too far away from you, me being in CT. but if you need somethihg that is small let me know i may have it.

Andrew

Daniel H. · Jul 16, 2008

I believe they turned the RPMs up on the 140 to 1800. A Super A is 1540. That may be why they changed the gear ratio. I have always heard, but never compared myself, that a 140 is too fast cultivating compared to a Super A.

Hugh MacKay · Jul 16, 2008

Terry: R11 and R21 will be no different in size, R21 is just a later casting production run. The case hardening process changed in 1953 during Super A production. Gears after that time should be more durable.

I've never checked out gear ratios, however I do know my SA achives the same speed in feet per minute turning 1540 RPM with 9.5x24 tires as my 130 does at 1650 RPM with 12.4x24 tires. My 140 is a bit faster with 12.4x24 tires, and I expect this is due to engine RPM and 130 and 140 are indeed the same ratio. I know this as I have them all calibrated for spraying, thus we calculated it in feet per minute. This feet per minute was done in both 1st and 2nd gear, we had no reason to check 3rd and 4th.

Super A Xmission in a 140?

NawlensGator

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Andrew Z

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Andrew Z

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Daniel H.

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Hugh MacKay

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