Transmission questions

My truck started life with a 3 speed transmission. Somewhere along the line some one swapped in a four speed. Today I was under the truck and scraped some crud away on the side of the tranny and saw the numbers T 9 . IV which makes me think it must be a T9 except it was my understanding they were non- synchro . When I have been driving the truck the box acts like a synchronized unit and I have had to do little in the way of double clutching to shift.

So I'm wondering was there a synchronized version of the T9?

Am I missing markings somewhere else?

Any input on what I may have?

And what oil is right for it?

I'm gonna be watching this posting REALLY CLOSE, cause I've read so many tranny discussions here, it leaves my head spinning. I've saved every post on the subject that I could find, and after reading them all, the whole subject is still as clear as mud in my mind. Maybe I'm just plain dumb, but, when all the answers are in on this post, I'll save it, too, so I can go back at some future date and review them all over again, and try to get it clear in my brain.

Well,...

I have a T-9 in my S132. What I know is this. It is a 4 speed, with granny low. 4 on the floor. Granny gear is synchronized for whatever its worth. I've only used granny gear once when I had 6000 lbs of concrete in the back of it.

The other 3 gears are definitely not synchronized. As I crash them often, even double clutching. I actually think I am pretty decent at it, it just sounds bad when you are not exactly on.

I have posted pictures of my T-9 when I rebuilt it, so do a search an you should be able to see a few pictures.

I do know that the T-9 transmission made by Borg-Warner ( I think) was also used in several other cars with multiple flavors. I want to say the most common was for a Ford Mustang. When I rebuilt mine I think I actually ordered a Ford gasket kit.

Well it looks like I opened up a can of worms with this subject! I drained it the other day getting ready to refill it with 50 weight motor oil but now I'm not so sure this tranny calls for it. If anyone sees a reason not to use 50 weight give a shout out. Other than a curiosity as to exactly what it is the transmission works well so my main concern is the oil.

From the IH factory service manual, CTS-11/12, found at John Hansen's site and accessed via THE LIBRARY section on this website:

Under the LUBRICATION section:

TRANSMISSIONS
When possible, always drain transmission
when truck has come in from a run. With the
oil warm a more thorough draining job can be
done, especially in cold weather. To drain,
unscrew plug at bottom of case and allow sufficient
time for all the old oil to run out. Before
refilling, flush with light engine oil or
light flushing oil, followed by complete draining;
this will remove thickened material within
the case. Use SCL, EP gear oil or multipurpose
gear lubricant.

In the TRANSMISSION section of the CTS-11/12, the T-9 is also referred to as the H-41-B. Fluid capacity is listed as 5 points.

Thanks for posting that and thank you for letting me know where to find the online manual . I have a reprint of the original but it lacking in certain areas, almost as if pages or entire chapters got left out! It can be frustrating to use.

As far as I know, the T-9 is a non-synchro transmission in any gear. SO gear oil could be anything from what it originally had, probably GL-1 straight mineral oil, to GL-5 or 50W motor oil (both the same viscosity). The bigger concern is with transmissions with synchros, as the GL-5 additives have a tendency to eat yellow metals. Except maybe Swepco, which claims to be okay for such things. I wonder if you uncovered "T-9", but still have a little crud over the last digit, and that maybe it's a "T-98", which would be synchronized in 2nd, 3rd and 4th. I haven't heard of any of them being synchronized in first gear until the T-19 in the 70's.

Something to keep around. I don't recall where I found this, probably on this site somewhere.

When in doubt, just about any IHC transmission will be fine with SAE 40 or 50 engine oil. There is one exception, and my memory as to which one (I think it is either a Warner or Spicer) that uses double row of needle bearings in the countershaft, that trans calls for 10W40 only, to assure to flows around the needles.
Transmission are fairly easy on oil, if it is wet and a lubricant you aren't likely to do harm, although the correct called for is best.
I once saw a transmission from a Loadstar that was packed with white grease! all the bearings spun in the case, but the gears were fine!
Multi propose gear oils GL-2 thru GL-5 are not recommended for transmission with syncro's not because of the yellow metal issue (most all are now low in Sulphur compounds that attacked the yellow metals) but because they have friction modifiers (EP additives) that effect how the syncro rings work.

So the mystery goes on, at least for awhile until I can clean up the case more and have a good look. I may just have the smoothest shifting non-syncro transmission I've ever owned! The other two I had, one being my 51 L112 was a real crash box and took a lot of practice and precise rpm matching along with double clutching to get smooth shifts but I mastered it. At the same time I owned a 45 2 ton army truck that was a lot easier to shift than the IH so I had the two to compare side by side, neither compare to what I have now. After owning a number of trucks with crash box transmissions I will say that to this day anything I drive with a stick shift I sometimes unconsciously double clutch out of habit.

CB89, thanks for putting my mind at ease about the oil, I will go with the 50 wt that I picked up for it.