1946 Farmall B Transmission Rebuild

Farmall B & BN Tractors, 1939-1947

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1946 Farmall B Transmission Rebuild

Postby Urbish » Sun Feb 25, 2018 6:36 pm

The transmission in my 1946 B leaks pretty badly and the 3rd/4th gear pairs are badly chipped. They make a terrible racket. I flushed the transmission this past summer and pulled out a LOT of metal chips/filings. I split the tractor today and got the transmission on the bench. Since there is no guide for the B on this site, I figured I'd at least document my steps so that others can benefit.

The first step was to construct a sturdy splitting stand that not only would support the middle of the tractor but would keep it from tipping over (since the front end is narrow). You can read about/see that here: http://farmallcub.com/phpBB2/viewtopic.php?f=177&t=99083. My wood Cub splitting stands are detailed here: http://farmallcub.com/phpBB2/viewtopic.php?f=1&t=89914

I supported the rear of the tractor with jack stands at the finals, drained the oil from the transmission and pto, removed the rear wheels and centers, seat, pto assembly, transmission cover, fenders, and all the fasteners for the operator platform. The operator platform does not need to be removed and can be flipped out of the way so long as you support it so it isn't hanging off solely by the brake pedal shaft. I disconnected the brake yokes from the brake band rods.

With the tractor being supported by the front wheels, splitting stand, jack stands at the finals, and a floor jack under the transmission, I unbolted the final drive/axle extension assemblies from the transmission and lifted/removed them with a cherry picker. Once they were removed, the splitting stand would hold the weight of the transmission. I then used the cherry picker to support the transmission while I unbolted and removed it. Note that much like the Cub, the input shaft to the trans is attached and comes out with the transmission. Leave yourself plenty of room behind the tractor to move it rearward and to clear the clutch housing.

I began taking the transmission apart. The transmission input shaft seal retainer is very wallered out and is cracked everywhere. It had gaps greater than 1/16" at the three worst points around the seal. As some point the previous owner replaced the seal and attempted to use electrical tape to seal the big gaps. I'll try to find a new retainer (good luck!) or maybe I'll try to get fancy with some JB weld and this one. Looking at the other gears in the transmission, I might replace the 1st/Reverse countershaft gear as well as the 1st/2nd sliding gear as well. They're all in pretty bad shape.

A question for anyone who knows, should the clutch linkage lug be bent over to the right like that? I enjoy knowing that it has been linked for who knows how long with a bolt and no nut, being held in place by gravity and luck.

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