Engine/sherman from 640, into 641, lots of questions

Hey guys.

I spent the day pulling the gas (134 I think?) engine and Sherman up/down transmission from a donor 640 tractor. I'm planning to put them into a 641, formerly with a 144 diesel.

I've done a number of engine swaps in my old Ford truck, even with non Ford engines, and from the start was surprised by how interchangeable the parts are and how smoothly the swaps typically go. The sailing doesn't seem like it's going to be so smooth on this project unfortunately... and surprisingly. I figured a tractor would be a big step simpler than an automobile, so I'm surprised to learn that the Sherman transmission from the 640 has a completely different input shaft than the shaft that came out of the 641.

I know the flywheels are significantly different, but I was told that the 3.5" thick flywheel from the 641 would work with the engine and sherman from the 640 and the bellhousing from the 641. I figured the bell from the 641 must be that much deeper than that of the 640, or something along those lines.

I really hope there's still a way to make this swap work.. it obviously won't be with my 641 clutch disk (newer style, 10", 15 spline). Could I install the old style ten spline sherman in the 641 bellhousing, and just buy a 9", ten spline clutch disk and pressure plate, and run that against the ~2" thick 640 flywheel, in the 641 bellhousing? The nosecone is different between the two ages of shermans also. Will my clutch fork in the 641 be in the right place for the 640 guts? I'm shocked by all the differences, as I said, between two tractors only two years apart in age, of succeeding models.

Thanks for any guidance. Alex
 
What's your serial number on the 641. It's obvious that your 641 serial number is over serial number 14256 when the change was made for the 10 spline to the 15 spline input shaft. They also changed
the output transmission shaft at serial 54166 from course to fine spline so If your is less the the 54166 than an easier swap might be to include the transmission from the from the 640. I know the
left brake cross over was different but I don't think that's a big deal. Clutch pedal was also different but might not be a problem either.
If you can find one it might be easier to change the sherman input shaft and nose cone. Some times you can find some one will the trade. The plate inbetween the engine and and flywheel might be a
different size also.
I have used the clutch and pressure plate from an 8n in a late '57 640 so it may also be possible to go with the 10 spline clutch. As long as you're using the old flywheel for the 9" clutch I don't
see that it would be a big deal.

Kirk
 
BTDT The 15 splined shaft came on the 4 speeds at SN 14257 on the XO1 series tractors. Clutch pedal mounted to the side of the transmission, not on the brake shaft in front of the transmission. We used the 640 flywheel. We put in a 9 inch clutch and pressure plate My flywheel was already drilled to except a 9 or 10 inch pressure plate, (hole spacing's are different) so as to use the 10 Sherman input shaft. We then "engineered" two throw out bearings together so as to reach the pressure plate. A long way from being original but it worked. Make sure you have room on the side of the transmission case for the handle. You will be awful close to the starter bulge. In my case (a 541) I made a totally different shifting mechanism. I have pictures but am too old ,or not smart enough to know how to send them. email should be open.
 
Ahhhhhhh boy. Another homemade frankenstein job in my future I guess.....

I was so looking forward to just dropping in the new engine. I had wanted to rebuild the diesel, but ended up settling for a gas swap because the time and money to rebuild the diesel were going to be silly. Now the gasser side is climbing too, but I'm already into that one.......

My 641 is SN 66171. Is a 9" clutch big enough to do the job?? There had to be a reason for them to step it up to 10".

The transmission on the 640 is shot, so swapping that in is out, but what about the bellhousing/tubular section between the tranny and engine? I was going to have to hole saw through the 641 bellhousing anyway for the Sherman shifter shaft. Now that my brake and clutch mechs will be all mudded up, maybe it would be easiest to go with the 640 bell? Does that section switch out between the generations?
 
The bell housing is also the whole transmission, case and all, plus all of the left brake mechanism. How good are you? Can you bore the two holes for the left brake shaft into the 641 transmission housing. On second thought I'm thinking the present 641 clutch shaft might be in the way. .I think your best bet is get a Sherman 3-speed with the 15 splined shaft. They show up every once in a while on ebay
 
Hate to muddy up the waters even more but if it were me I would
probably pull the 641 transmission and transfer all the gearing
into the 640 trans case assuming that when you said the trans
was shot you were referring to busted gear teeth and not a hole
in the case.
This Way you wouldn't have to be drilling holes or replacing
clutch or input shaft and as far as cost it would probably be a
gasket or two
Save money but the work might be about the same. By pulling the
gearing out of the 641 you'll have the right spline for your
coupler
Make sense?
 
Ah, ok right, the tranny and bell are that same center section, duh. I guess seeing how deep the "bellhousing" was, I figured it was a separate section with its own flanges, ahead of the tranny section, but in actuality that back wall that the sherman bolts to is just an internal divider, with the tranny guts behind it, and then behind that is the flange to the rear end section. As you can tell, I didn't look at things too closely yesterday, and am now embarrassed.. I was in a rush to beat weather and the end of my work day, and really only expected to strip to the long block anyway. It's also been a year and a half since I took apart the 641, and as I've said I never expected things would be so different between the two machines, so I didn't really look behind the engine.

I can't buy another Sherman. The cost makes it out of the question. I can't afford to have tractors just for a hobby, and while I will make some money off using this one in the loooooong run, a little kubota 4x4 would've been better for the small scale of agriculture this machine will be engaged in, and my neighbor's 545D Ford is obviously great for more serious digging, lifting, and hauling jobs, I'd just like to stop having to put time on his machines. Point being, I don't reeeeally need this machine to get by. I got the 641 with a loader for $400, that was fine, got deeper than I wanted to when I found out how ridiculous the diesel would be to rebuild, then this week finally dropped $1k on the 640 for the supposedly running engine and the Sherman, which were both supposed to drop right in. Now I'm $1500 into a tractor I don't explicitly need, and looking at a decent amount of work to get it moving, still.

*If it's possible* I like the idea of gutting the 641 trans, throwing that into the 640 housing, and using that. I don't have the first clue if all the parts will switch in though, especially without having to buy stacks of thrust washers and bushings and spacers and custom bearings etc? I also don't know what is "shot" about the 640 tranny. The previous owner told me he got the gears to it in a box, with the tractor, because the owner before him had torn into it after it failed, and decided not to repair.

I am pretty "good" with this kind of work. Metal fabrication is my profession, but I don't have many machine tools yet, so when it comes to precision my options are very limited, and many things have to be file finished, which can be prohibitively laborious or time consuming for some needs. The 640 also didn't come with a clutch disk or pressure plate, and the flywheel surface is badly rusted. The seller told me the flywheel from my 641 was what I'd need anyway, so I didn't factor any of this into my purchase decision. I had felt that a thousand bucks for a running engine and a functioning Sherman, two good rear wheels, was a fair deal.

More than anything maybe, I now wish I'd set this whole circus up indoors........... but it's winter, and indoor space is at a premium, and this was only supposed to be a simple engine pop.

Other votes for the possibility of putting the 641 tranny guts into the 640 case, assuming the case is ok? Will that case bolt up to the 641 rear section?

Thanks guys
 
I don't know how I could clutter up is situation so bad .Take the flywheel, pressure plate and clutch from the diesel and put it on the 640 engine and put it back together, period. There is nothing wrong with the tranny and back on the 641, is there?
 
The clutter is he wants to use the Sherman but he's got the wrong shaft & cone. He can do as you say along with the engine plate,and just use his 641input shaft and leave the Sherman out.
Find someone will to trade, I've done that a few times, and stick it in later. Would mean another split at a later date but that ain't no big deal
 
I don't remember making this switch but see no reason why it
won't just bolt up. Always best to compare the two cases when
you have them off. Some of the gearing Carried from the 8n up
thru the early thousand series, not reverse gears, thank God.
you can cut the left brake pedal on the ,640 but the rod thru
the trans bellhousong must remain.
Let us know how you will processed and you process

Kirk
 
Huh. I like that idea guys.. put it together the simple way now, see what I can do with it the way it is (see if the 640 engine even does run, if the old loader even does work, build an implement or two, etc). See how much I'm hurting for a lower gear, how much time I have on my hands in a couple months, where my budget stands. Watch for a trade in the meantime, or maybe even sell my Sherman if I decide I don't need it. Move on to other concerns after a relatively quick swap now, and if I do want to put a Sherman in later, do it without monkeying up the whole thing. It's the "take a step back for a minute" approach.

Thank you very much for that advice! It's easy to get so wrapped up in a problem that you lose sight of the bigger picture, especially in the winter..
 
See how much I'm hurting for a lower gear

Really depends on what type of work you intend to do and with what type of implements. Any PTO driven implement that you want to slow the tractor down for will not fare well with a Sherman because the Sherman will also slow the PTO down.
 
Yes, understood. The only driven implements I see myself using right now would be a hydro pump for a log splitter, or a rototiller. I know the ground speed is too high for a tiller anyway, and with the Sherman under the pto speed is supposedly too low, so I'm not planning to be able to run a tiller on this machine right now, unfortunately.

I want to knock my speed down simply to have more fine control of the machine for utility work, and maybe a lower speed at higher torque. The first implement on my mind for use this year, besides the loader, is a subsoil ripper, and I would think it would be nice to run that at a lower speed.
 

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