Select-o-speed models/changes

pomester

Member
Is my understanding correct?

Select-o-speed transmissions rolled out with the XX1 models. The 871 and 971 tractors had 540 rpm PTO while the 881 and 981 had 540 and 1000 rpm PTOs.

Were/are there 671/681 and 771/781 models?

The transmission consisted of two series, an early with a number of freewheeling gears and a later (thousand series?) without the 'coasting' feature/flaw?

The most common failure is associated with the splines associated with the clutch and service parts associated with stripped splines are not available other than the used market?

Is there any difference in the transmission between the 8X1 and the 9X1 tractors? They will interchange both as a unit and the all the internal pieces are the same?

Just wondering as I have a 981 (that I purchased ~30 years ago and did a partial disassembly to replace a planetary unit - the transmission still works and the tractor is actually my favorite and sees regular farm use). I am looking at a transmission from a 881 just to have spare parts, but don't have much interest unless it's the exact same unit. -

thanks
David
 
The X81s also had ground speed PTO.

Not sure about the 7s, but there were 6s. Likely were 7s.

If you're talking about the TLC, I think the clutch disc is still available. The *81 input shaft may not be available new.

Any SOS transmission with the deluxe PTO options from '59 through '64 will interchange.

Blue transmission parts will not all fit the red transmission, as the blue has a direct drive clutch to facilitate direct drive ratios, whereas the red uses an over-running clutch for this purpose. Neither will red all fit in the blue.
 

Actually . . . there were three different SOS transmissions between '59 and '64. The blue transmission was upgraded in '63.

As general rule, though not always the case:

The X01 transmissions would have the number 312259 on the left side in raised cast letters. This is the Red or ORC transmission.

The original Blue or DDC transmission would have C0NN-7006-B on them.

There were more versions of the SOS from '65 through '74.

The 2nd Blue or DDC transmission would have C3NN-7006-B on them. Basically this transmission had a redesigned input shaft and front plate and maybe pump.
 
I have many of the same SOS questions too. I've been told the 6000 for example has no rear transmission planetary gear set, uses 6X40, 6.66-1 ring and pinion gearing, and axle planetary gear reduction of 4.5 to 1 on late models. I have a 4000 utility rear with 6X43, 7.16-1 ring and pinion, and a row crop that has a 37 tooth ring gear, but not sure of the pinion, guessing it's 6 tooth like the others, for 6.16-1 ratio, and drop box axle gearing 15T drive, 32T driven for 2.133-1. The books show the 4000 has a reduction planetary on the SOS rear on both models, but are both utility and row crops the same? The speed charts show both 4000 models have the same gearing with 13.6 X 28 tires. Been thinking of mating a 6000 diesel engine/SOS to a 4000 rear just for grins and giggles..
 
TLC = torque limiting clutch, correct? I was trying to think of that when I typed out the original post, couldn't come up with it, and was too lazy to research.

My 981 drags a heavy sprayer around and I dread the day I upshift and the tractor stops
 

Larry is there a difference in the cases.
We have a CONN with the starter mount broke out of the case.
We have a couple of the early 312259 trans.
Was wondering if we could swap all of the C0NN's internals into a early case.
 
(quoted from post at 23:18:25 03/07/19)
Larry is there a difference in the cases.
We have a CONN with the starter mount broke out of the case.
We have a couple of the early 312259 trans.
Was wondering if we could swap all of the C0NN's internals into a early case.

The 312259 has to have some boring done to facilitate the DDC tubing in my understanding. I've never contemplated doing such, so don't know the exact details.
 
(quoted from post at 22:45:37 03/07/19) TLC = torque limiting clutch, correct? I was trying to think of that when I typed out the original post, couldn't come up with it, and was too lazy to research.

My 981 drags a heavy sprayer around and I dread the day I upshift and the tractor stops

Correct.
 

Thanks!
The C0NN is apart but we haven't pulled the any of the 312259's apart yet.
Once we get two empty cases side by side we'll see what's involved and if it's worth the effort.
Probably not going to do anything to my 881 as it's pretty much all original and still operates.
My brother has two 671 diesels and both have bad inputs.
We have a 5 speed conversion for one but he wants to keep the other one SOS.
We have some young nephews that will be operating it at times and I don't want them on our hilly farm with a ORC trans.
 

Thought I'd contribute a little more to this thread, might help some one else searching for info on repairing SOS transmissions. John Smith used to have a website with tons of useful data on old Fords and SOS transmissions. A few years ago, he passed most of the info for the older 9N, 2N and 8N tractors to this website.

Regarding SOS input shafts, he had a rather interesting fix. You can still see this at the link below:

https://fordtractorcollectors.com/repairing-a-select-o-speed-input-shat/
 

Thought I'd contribute a little more to this thread, might help some one else searching for info on repairing SOS transmissions. John Smith used to have a website with tons of useful data on old Fords and SOS transmissions. A few years ago, he passed most of the info for the older 9N, 2N and 8N tractors to this website.

Regarding SOS input shafts, he had a rather interesting fix. You can still see this at the link below:

https://fordtractorcollectors.com/repairing-a-select-o-speed-input-shat/
 
Thanks for the link - I'd not seen that repair before - makes me feel better about the possibilities

I'd still like to get a spare unit on hand -
 
The 13/16 repair for the input shaft only works on low HP and parade tractors. On a SOS if used under any hard pulling will crack. The input shaft is hollow and under oil pressure. 13/16 makes them paper thin and they don't last long. When they crack they start leaking oil really bad. We started to weld them with tool and die rod and machine them to 1 inch. This is the biggest size that will still pass through the oil seal. First few I have done are still going, but we don't pull SOS like we did 25 years ago. Al
 

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