Ford 881 SOS trans

[FarmerBlair]

Hi,

For years the select-o-speed on my Ford 881 would act up when first started cold. It would initially engage in gears normally seconds after starting the engine... I'd back it out the barn and go forward in a gear lower gear (1-4). But about every time, the transmission would disengage a few minutes later and stop running under power. Shifting the lever into reverse, 1, 2, 3, or 4 would be non-responsive. If I let it sit and warm up for several minutes, it would start shifting normally and work the rest of the day no problem.

I discovered that the higher gears (5-10) would work normally when cold even while I still could not shift into R,1,2,3, or 4. The other day when I could not shift into the lower gears while it was cold, I tried shifting up to the higher gears (5-10), and then immediately went back down to the lower gears (1-4), and they now worked just fine, including reverse. For some reason engaging the higher gears first and then backing down would make R,1,2,3, and 4 start working normally without having to warm the tractor up.

Any ideas what is going on? I adjusted bands last November, though that makes no difference on the shifting behavior when cold. The oil level in the tranny is good, though its probably due for a change since last time was maybe 6 years ago.

Thank you

 

[IndFord]

Did you get the pressure readings off all three servos?

 

[FarmerBlair]

No, I've never done any oil pressure readings.

 

[Dean]

Correct oil?

When was the suction strainer last cleaned?

When was the filter last changed?

Dean

 

[FarmerBlair]

Tranny oil is Valvoline 813.
Suction strainer and filter last changed with the oil about 6 years ago.

 

[Dean]

Not familiar with 813. Does it meet CNH 134D spec?

Dean

 

[Sean in PA]

I just looked it up, and Valvoline 813 is officially called "Valvoline Unitrac Hydraulic Fluid" and it says on the label that it meets or exceeds the 134 and 134D specifications.

 

[Dean]

As the issues appear to be intermittent, I would suspect sticking valves in the valve manifold.

Since it's time for service anyway, and you have already adjusted the bands, I would suggest inspection/cleaning of the valve manifold and valves while you have the top cover off to change the filter. Verify
proper adjustment of the shifter upon reassembly.

Dean

 

[Dean]

Sorry, response was intended for OP.

Dean

 

[FarmerBlair]

I'll check out and clean the valve body as you suggested. Sounds like a good idea. I actually have an extra new unused valve body I got years ago from NH that I stored (somewhere) oiled in a ziploc bag. Maybe I'll try swapping out the old one with the new just to see if that improves things.

Thanks for the responses.

 

[Dean]

Interesting.

I too have a NOS SOS valve body.

Dean

 

[showcrop]

Leroy at Page Implement in Luray VA rebuilds the control valves. along with the whole transmission. If you were to enter your location in your registration someone may tell you of an SOS expert just down the road from you. You can't go by hours to govern oil change intervals in this old equipment, especially when using UTF or any modern oil that clutch packs need. The additives suck moisture out of the air and if you aren't working it and driving the moisture off regularly your oil will get seriously moisture and rust contaminated.

 

[FarmerBlair]

Thanks Showcrop. I'm in NJ. There isn't anyone around here that I would trust with the SOS, or even a standard transmission for that matter. The one time a tried someone local to work on a tractor (less than a couple years ago), it cost me over $5 grand for a screwed up complete engine rebuild for my 861 gas that I just found out last week needs new main engine seals replaced along with new bearings for another $1000. There's an outfit in Indiana PA that does SOS rebuilds, so that's where I would probably take it if need be.

 

[showcrop]

(quoted from post at 13:37:32 04/20/21) Thanks Showcrop. I'm in NJ. There isn't anyone around here that I would trust with the SOS, or even a standard transmission for that matter. The one time a tried someone local to work on a tractor (less than a couple years ago), it cost me over $5 grand for a screwed up complete engine rebuild for my 861 gas that I just found out last week needs new main engine seals replaced along with new bearings for another $1000. There's an outfit in Indiana PA that does SOS rebuilds, so that's where I would probably take it if need be.

Farmer blair, did you see the part in my post abut oil? Oil in a transmission is critical.

 

[FarmerBlair]

Showcrop, yes I did see your points about the oil. I check the oil level at least yearly and I do think about moisture getting in the oil if the tractor sits a long time since I live in a climate conducive to condensation. During the winter I run the tractor at a fast idle parked in the barn for a half-hour about once every 2-3 weeks to warm it up, hoping it will help evaporate out moisture in the transmission oil, though I don't actually know if that makes much difference since I'm not driving it. The rest of the year I use it fairly often and that transmission housing gets pretty hot, so I wouldn't imagine there is a much moisture in there during that time. Maybe I should just go back to changing the oil every couple years, but would have to reconsider using VV813 oil which is about $130 for a 5 gallon pail.

 

[Destroked 450]

(quoted from post at 14:16:37 04/19/21) I just looked it up, and Valvoline 813 is officially called "Valvoline Unitrac Hydraulic Fluid" and it says on the label that it meets or exceeds the 134 and 134D specifications.

We had issues with Valvoline Unitrac years ago in a
Ford A62 wheel loader nearly burning out its Allison transmission
Turned out Unitrac is based on 30w oil and was to thick
Allison recommended 10w hydraulic oil
Ford tractor hydraulic oil is based on 20w hydraulic oil

May not be your problem but I wouldnt run Unitrac in a SOS transmission

 

[showcrop]

(quoted from post at 20:35:35 04/21/21) Showcrop, yes I did see your points about the oil. I check the oil level at least yearly and I do think about moisture getting in the oil if the tractor sits a long time since I live in a climate conducive to condensation. During the winter I run the tractor at a fast idle parked in the barn for a half-hour about once every 2-3 weeks to warm it up, hoping it will help evaporate out moisture in the transmission oil, though I don't actually know if that makes much difference since I'm not driving it. The rest of the year I use it fairly often and that transmission housing gets pretty hot, so I wouldn't imagine there is a much moisture in there during that time. Maybe I should just go back to changing the oil every couple years, but would have to reconsider using VV813 oil which is about $130 for a 5 gallon pail.

It sounds like condensation shouldn't be a problem but it is still a good idea to drain a little off to look at it a couple times a year. I got quite a surprise when I checked mine after it moved very little for a few years.

 

[derwen1959]

I am not familiar with sos but I know a retired ford
service guy who says atf should be used in sos

 

[showcrop]

(quoted from post at 07:21:44 04/22/21) I am not familiar with sos but I know a retired ford
service guy who says atf should be used in sos

He says wrong.

 

[FarmerBlair]

Thanks, that's an interesting point about the viscosity. A while back I read somewhere that there are hyd oils with lower viscosity than VV813 that still meet the 134D specs. At one point I had thought about trying a lower viscosity oil to see if it improves the time it takes for the tractor to engage into park since it requires the oil to drain from of certain transmission elements (servos?). I could be wrong about that and the terminology. As I mentioned before, it can take sometimes take a minute or more for the tractor to actually stop rolling after shifting into park. Maybe a lower viscosity oil would help with the other issues too, I don't know. I will have to research where I saw that info about the oil viscosities. But my guess is the valves sticking might be more likely the source of the problems.

 

[pomester]

During the winter I run the tractor at a fast idle parked in the barn for a half-hour about once every 2-3 weeks to warm it up, hoping it will help evaporate out moisture in the transmission oil, though I don't actually know if that makes much difference since I'm not driving it. The rest of the year I use it fairly often and that transmission housing gets pretty hot, so I wouldn't imagine there is a much moisture in there during that time. Maybe I should just go back to changing the oil every couple years, but would have to reconsider using VV813 oil which is about $130 for a 5 gallon pail.

Be aware that your steering gear box needs to be sealed to the case. In the case of the 4 and 5 speed transmissions the box covers the clutch/input shaft area and a bit of leakage is not a big deal. With the S-O-S the box covers the transmission proper and any leakage ends up in the S-O-S fluid.

I have a S-O-S and had trouble with contaminated fluid, turned out to be a deteriorated gasket under the steering box.

 

[showcrop]

Thanks pomester, that is good to know

 

[FarmerBlair]

Thanks Pomester. That could be a problem here too, as I do get a bit of oil seepage where the steering box mates with the case. I ordered a new gasket at NH. Not looking forward to removing the Wagner loader, the tin and steering box to replace it!

 

[pomester]

When I checked CNH no longer serviced the gasket - I bought a roll of heavy gasket material from NAPA and fabricated one. Same with the transmission cover. I've read here that the 5 speed gasket will work for the transmission cover, but it does require modification, a new gasket out of the same material from NAPA was straightforward to make.

In your case you might consider loosening the tin and raising the steering assembly with a hoist enough to clean the surfaces and use some silicone for a gasket. That sounds better than removing a loader...

5 speed gasket is close, but not quite.

I made a new one that fits right...

 

[FarmerBlair]

Pomester,
Nice pics! I had called CNH and they are ordering the gasket that goes under the steering box. They didn't say it was NLS. The odd thing was the gasket for the tranny top cover. CNH has two gaskets listed for the 881 (86569737 and NDA7223A), where the first costs $69.75 while the other is $23.75!! Not surprisingly, they only had the $69.75 gasket in stock. The parts guys could not figure out if there was any difference between the two gaskets (no diagram rendering). If anyone knows, that would be great info to share. I could order the cheaper one, but if it doesn't fit, I would be stuck paying a re-stocking fee. I'd cough up the 24-bucks if that one fits, but I'm not about to pay $70+ dollars on this simple gasket. I've thought about making the gasket, so your tips and pics on gasket making are timely. Preferably the thickness would be close to original since I think that could make a difference in the pto/shifter cable adjustments. Maybe silicone would work, but not my first choice as I would worry about overdoing it and possibly dropping some into the transmission.

I've tried years ago hoisting the steering box up enough to get to the gasket without removing the loader. It could be raised maybe an inch at best. So I think my headache will be smaller if I just bite the bullet and take off the loader.

 

[pomester]

I think the SOS top cover gasket is metal or fiber depending on the year. I rebuilt this transmission in '97 and got a metal gasket from the CNH dealer when procuring parts. It seems reusable, but I've had the lid off/on a few times over the years and felt it was time for a new piece. The roll of gasket material from NAPA was less than $5 and I can't see paying CNH prices for something so easily fabricated.

There is a hole at the left rear of the transmission cover opening from the gasket surface into the transmission case - no bolt, I don't know why it exists - visible in this picture above and behind the spring. It is another location where moisture could get into the transmission if the gasket is not fit properly/carefully.

 

[Vito]

Tony Jacobs in MA knows the SOS transmissions inside out.

Vito

 

[showcrop]

(quoted from post at 17:21:08 04/26/21) Tony Jacobs in MA knows the SOS transmissions inside out.

Vito

Yes, Tony is very knowledgeable on the SOSs as is Leroy at Page implement. Leroy has a rebuilt control valves on hand and a rack of rebuilt SOSs. It appears that Pomester knows his SOSs outside in.