Hupp Overdrive for 640 Ford

I am helping a friend of mine split and install new clutch, after splitting tractor we found the Hupp overdrive had an issue with a previous owner. The snap ring is spot welded in place due to the casing is broke that holds the snap ring. I have never worked on a Ford, I have IH's, so alot of this is new to me. The very small gear on the overdrive is missing over half of it's gear teeth, is this overdrive assembly available,for sure we need overdrive housing, small gear, is the small gear the high side of the overdrive? All your help on this is appreciated!!....Thanks for all your help....Binderman

The Ford we are working on is a 1957 Ford 640..Binderman

A Hupp in a 640 would likely be a Dual Drive (over/under). I have some Hupp parts, but don't know what you're referring to for a casing or which snap ring or gear. A picture of the broken parts would be great.

First question, are you sure it is a Hupp? Thought those were more from the 9N/2N/8N era.
Check out the link below for a positive ID.

Second, you probably know this, but a Hupp is not a factory option, so is not original to the tractor. Ford did install Sherman auxiliary transmissions from the factory, though.

If it is a Hupp, you will have a very hard time finding parts, or even whole transmissions. Those haven't been made for a very long time, and was not the most popular brand out there (Sherman being the most popular by far). Probably best to either remove it or buy another complete used auxiliary transmission. Not sure which one the small gear is. A picture would be very helpful. If you do enough asking, maybe somebody might just happen to have the part you need. Might try looking on Ebay as well.

If it is a Sherman, then you probably will be able to find parts. I don't believe any new parts are available, other than bearings, but there are plenty still out there so used parts are available with a little looking.

One thing to note, I know right around 1957 Ford changed the number of splines on the clutch disc from I believe 6 to a lot more. So you will need to make sure the shaft matches the clutch if you buy a complete unit.

If you decide to replace or remove it, let me know. Might be interested in it for parts. Just drop me an email.

Good luck.
Smiths Tractor Site: Auxiliary Transmissions

pics of Hupp overdrive 1957 640...Binderman

Ok, now I see the problem. The nose cone snap ring groove is broken and the dentals on the input shaft are broken. Those are engaged when the Hupp is in direct mode, so you're going to want to replace that "gear". Unfortunately, it's part of the input (clutch) shaft, so you will need a complete input shaft. The nose cones came in 2 flavors, so you will need to be sure you get the right one. The picture below shows the dimensions of the pilot diameter. Yours appears to be the one on the left. You could also machine the weld off, and finish cutting away the snap ring groove. Then drill and tap for 3 setscrews and keep the bearing in place like the Sherman combination does, without a snap ring. Unfortunately, I don't have a good nose cone or input shaft to help you out right now, so you're on your own to find parts. FYI, the red color would indicate a model 049C that would have been a straight overdrive, but it could also be converted to over/under. Look inside the housing at the shift forks. If it has one fork it's an overdrive, 2 forks it's a over/under. The input shaft you need is the same for both models.


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First I would like to say thank you to John smith8n for all your help on this project! You were asking me about if it had one or two shift forks. the picture is of the front fork and there is one behind it, the number on the front fork is H252-33D, which matches up with the dual drive, question-- The tractor has the Hupp overdrive Trans. shifter, should this be the dual drive trans. shifter, are they interchangeable? Thanks again John for all your time and help...Binderman

It has been converted to the dual drive. The step up shift lever still works fine, you just need to shift to neutral, then pull it outwards and up to get the low range.

Thanks John for your help, my friend who owns the tractor has a boat and motor sales business, and uses the tractor for moving boats around and forks on the loader for unloading boat motors on pallets, so it is used mainly for business, no plowing or heavy work, Thanks again, I'll keep you posted on the rebuild....Binderman