SOS trans

I am looking at a Ford 4000 with a SOS tranny. I have read that later tractors with this transmission hold up better than earlier ones. Is there a serial # where you could tell if it has the improved trans ? Or should I just avoid the tractor entirely. I have heard a lot about the SOS tranny, almost none of it good.

A 4000 would have the improved SOS in it since it was the early ones that caused the most problems and those where in the 801/901/601/701 series tractor and made before the 4000 came out. But that said if not serviced as they should be even the later ones can be a big money pit.

Remember that Ford built two different 4000s.
The pre 1965, 4 cylinder model and the 65-75 3 cylinder models.
So it's always best to let us know which one you are referring to as they are completely different tractors.
They pretty much had all the bugs worked out of those transmissions by 1963 or so but they did require regular maintenance which many did not get.
Many parts are no longer available or so expensive you can't afford them.
The price of an SOS tractor reflects their less than stellar reliability today even though it was the early years that gave them their bad reputation.
I don't have much experience with them but did buy my first SOS tractor here recently - a 3 cyl 4000.
Ask me again in 5 or 10 years and I'll be able to give you more info.

Agree with what the others posted, if the one you look at checks out to work properly in all gears after its been running at operating temperature, its possible that its in decent shape, requiring routine maintenance and adjustments, the correct manuals for these are a necessity. Use the correct modern equivalent of specified fluid and maintain it, very possible for it to be trouble free.

Some love or hate these transmissions, I had a '64 4000 for years with no trouble, it did all the chores, hay, snow removal, lots of cutting with the rotary mower. I can recall baling hay with this tractor with a 532 Ford baler, handled that just fine. It had independent pto,(there are variants with ground and 1000 rpm pto) power steering and one set of remotes, it was a good running and nice operating tractor with a gear for every task. Some say they are a bit jumpy when shifting or starting off from a stop, and if you do a search here, you'll see some typical problems from the shift lever adjustment, certain groups of gears and suggestions on where to start with repairs or adjustments.

At this point its important to figure out if the one you are looking at is operating correctly with no signs of problems. They are a bit complex and the details are better known by someone familiar working on them, as well as in the manuals, (Ford Shop Manual, not I&T for these)

I would not hesitate to own one knowing how they performed, but the resources available for these are definitely not as abundant as other models, yet I've seen a few with alleged rebuilds and similar at times for sale, so apparently they are not so obscure and obsolete, there were a lot of them built and many are still working today. We sold them new in thousand series way back when.

It is true about being potentially costly to repair, you really have to make sure then one you are looking at is in good operating condition.

Like other posters have already said, all 4000 model tractors have the significantly improved S-O-S transmission, though there are differences between those used in prior 4 cylinder models and those used in post 64 models. Specifically, a much needed water to oil oil cooler was added with the introduction of the post 64 models, as was an externally replaceable full flow oil filter.

The externally replaceable filter most likely resulted in much more frequent filter changes vis a vis the early models, which had a small afterthought filter beneath the top cover plumbed into the return line. Replacement required removal and replacement of the top cover. As a result, these filters were rarely, if ever, changed.

Like parts for the five speed transmission, some S-O-S parts are NLS or expensive.

Dean

for years the wifes uncle ran a tractor salvage lot. Those transmissions used to be piled up waiting for a load of them to go to the scrap yard. He would convert a good running tractor to a manual tranny. He was still doing this in the 1980's. Use your own judgment

Wow.

Wish I had a pile of them.

Dean