The Stovebolt Site Forums The Shop Area Driveline Torque tube school '46 1/2 ton (same as ADs?) Inquiring minds want to know

I need help. I have the original torque tube set up on my 1946 1/2 ton with a 3 speed trans. While I see many posts on the 'torque tube' set up, most apply to 1947 (ADs) and later.

I have several questions.

Does the transmission fluid flow into the torque tube on the 46 1/2 ton setup? If not, is there a seal at the back of the transmission that keeps the fluid from going into the torque tube from the transmission? Or a seal at the front of the torque tube to stop the fluid from coming from the transmission? If so, what kind of seal is it (are they) and how hard is it to replace?

Also, how many universal joints are inside the torque tube on the 46 1/2 ton and how are they lubricated? Per the link and verbiage below, there is one U joint at the back of the torque tube on an AD truck. Again, how is it lubricated?

Does fluid flow between the torque tube and the rear end? If not, is there a seal at the back of the torque tube or the front of the rear end that keeps the fluid from going between the torque tube and the rear end? and if so, again how is the U joint lubricated?

How does the knurled slip collar at the front of the torque tube come into play? Does it do any 'sealing' of fluid in the torque tube?

I have reviewed my 42-46 Chevrolet Shop manual for this information with no success.

I also viewed this thread which describes the function of the torque tube in an AD truck.

Previous torque tube thread

And this verbiage from that thread making me think the trans fluid should not go into the torque tube: "In the torque tube there are bushings and a seal, the latter keeps transmission oil from going down the tube to the differential. If that seal goes you will never keep oil in the trans as it will overflow into the diff and either blow out the vent or axle seals. Been there done that".

This verbiage references there only being 'one' U joint at the back, but again this was for an AD (47 or later). Was the setup similar/same in '46?

I also saw many references to an Okie bushing being used to 'seal' the torque tube. Is this ever done on a '46? Why an Okie bushing versus replacing the factory set-up?

I am asking all of this as I plan to pull the rearend and have a driveshaft shop install 3.55 gears. Since I'll have the torque tube out, I want to make sure it is sealed/set up properly.

Any help is greatly appreciated!!!!

Big T

1946 Oakie bushing.

The transmission fluid flows into the enclosed u-joint housing behind the transmission. That fluid does not flow further rearwards, due to a seal inside the forward-end of the torque (or the seal inside the oakie bushing).

The slip collar at the rear of the u-joint housing has a seal that surrounds/seals the outer surface of the torque-tube.

Thank you Tim. So is there only the one u-joint located at the back of the transmission/front of the torque tube? Is the seal for the Okie bushing one piece with the Okie bushing and do you know who has the seal for the slip collar? Thanks!

Also, does anyone have the specs (OD, ID, Length for an Okie bushing for a 46 1/2 ton?

The Okie bushing is both a bushing and a seal. When you install the Okie bushing, it pushes the old bushing back towards the rear end.

It seems to me that someone has posted dimensions for Okie bushings for different years (Jorb?).

Q.Does the transmission fluid flow into the torque tube on the 46 1/2 ton setup?
A.Yes, But only about 8 inch into the front of the torque tube.

Q. Is there a seal at the back of the transmission that keeps the fluid from going into the torque tube from the transmission?
A. No, the oil seal is in the torque tube.

Q. What kind of seal is it (are they) and how hard is it to replace?
A. Neoprene seal , Yes if its done by the book, No if you use a Okie bushing.

Q. How many universal joints are inside the torque tube on the 46 1/2 ton and how are they lubricated?
A. One U-Joint, By transmission fluid being funneled through the transmissions rear main bearing.
Complete Transmission and Torque Tube cross section

Q. Does fluid flow between the torque tube and the rear end?
A. No

Q. Is there a seal at the back of the torque tube or the front of the rear end that keeps the fluid from going between the torque tube and the rear end?
A. No

Q. How does the knurled slip collar at the front of the torque tube come into play? Does it do any 'sealing' of fluid in the torque tube?
A. Inside the torque tube screw on retainer cap (knurled slip collar) there is a oil seal and one washer on each side of the oil seal.
Which prevents transmission fluid from leaking out of the back end of the U-Joint ball housing.
Torque tube Crosssection Front end

History of the Okie bushing
The Okie bushing was created by the long gone National Machine Works Inc in Oklahoma, hence the name Okie.
It shortened the time and effort to repair the torque tube bushings and oil seal.
If you did it the way GM did it, you would remove the entire torque tube from the rear axle.
Remove ring & pinion gears
Pull out the driveshaft from the torque tube.
Use special tools to remove and replace the bushings and oil seal.
Then reassemble everything. Pain in the Butt.
With the Okie bushing you just pull out the front bushing.
Then from the front of the torque tube you push in the Okie bushing sleeve, which has the Front bushing,
Rear bushing & Oil seal inside the sleeve. Less Work.
Original set-up
Original front bushing removed, Okie Bushing Sleeve inserted
You leave the rear bushing and oil seal in the torque tube.
Okie Bushing Photo Album

Read this post
Bushing dimensions website

I used to make a point of checking trans fluid every now and then. One day it was empty so I checked the differential fluid and it came pouring out. The seal had gone. My nightmare.

Got the Okie assembly and pulled out the original bushing and drove in the assembly using an old u-joint shaft.
It was not a difficult job but when you are lying on your back on a concrete floor in winter it is a pain and time consuming. I found that if I took out the transmission cross-member (4 bolts each side) it was easier.

That was about 10 years ago and I forgot a lot of what I did but do know that if I do it again I will try to get it on a hoist. Having said all this I sort of lost faith in the seal and I would again check the fluid in the trans more frequently and it seemed okay.

Lately I have been finding a lot of gear oil under the trans and don't know where it is coming from. The differential is normal. It could be where the paper shims bolt to the ball housing, the large O-ring on the front of the ball housing or the smaller O-ring inside the knurled knob.

I believe it states in the shop manual that several paper shims/gaskets should be used to assess the movability of the u-joint assembly in the ball housing. I used the maximum number specified - 4.

I understand that the reason for the paper shims is if it is leaking at that point one can loosen the attachment bolts and literally tear out a shim at a time. This is supposed to tighten the leaking seal.

In my case I have leaked fluid at various spots on the transmission case. It could be somewhere else and moved to the lowest point. It seems like I will have to investigate those areas and this time I have access to a hoist.

After posting I crawled under the 49. No oil on the floor of the shop and the transmission seemed at the right level. Then I checked the differential and sure enough a few spoonful's trickled out. The truck had not been driven for about 18 hours so all oil should be level. But why did the diff overflow while the trans had an adequate level. I don't want to think the TT seal has gone again. Maybe its time to go open driveshaft. I have a centre section from a TF truck which will bolt in and a couple of TF 3 speed trans to work with.