Transmission / Overdrive: Where and What?

[Rafe Hollister]

I plan to drain and refill my 3sp top loading trans (3 on floor), OD, and Dana 44 rear end. I've googled this and get lots of discussion. As usual, too much info and choices gets my head spinning. I have read that different fluid goes into trans than OD, but that trans fluid will over fill to OD. And not to use modern stuff.
So what do I put in these three, and where do I buy it? I googled 80w mineral oil and got listings for food grade... could come in handy if my car breaks down on a isolated hwy and I am starving to death! -56 PowerHawk, trans is studebaker but not original style for car, it has 3 on floor now-
Thanks

[rbisacca]

Trans and OD are NOT separate. Only thing separating them is a bearing. Use straight 90W not 80W mineral oil.
Rear end uses regular GL-5 rear end lube.

[StudeRich]

So the only trick to properly filling the O.D. Trans. is:

Have the Car Level.

Fill the Overdrive Case FIRST, leave the Fill Plug out.

Then, Fill the Main Case, let them both Level out with a bit of time and a Pan under both, Plugs Out.

After 30 Mins. or more, Check that BOTH are still at the bottom of the Fill Hole. If not, make it so and tighten the Plugs.


As mentioned, the Diff. gets Hypoid Gear Oil GL-5.

The Overdrive gets Straight Mineral Gear Oil, GL-1 which has NO Extreme Pressure "EP" Additives, like higher GL Numbers do.
This is at Tractor Supply Stores and NAPA.

________________________________________________________________________________ __________________________________________________

Your actual Transmission is likely a Stock Borg Warner/Studebaker with either a Side Shifter Floor Shift Conversion Kit or a Top Cover floor shift from a Taxi, 1930's Model or Jeep.

The Model Number is RAISED on the Right side of the MAIN Case near the Fill Plug, it should be a T-86.

[6hk71400]

Get you one of these: https://www.acehardware.com/departme...E&gclsrc=aw.ds

You don't have to use ACE Hardware. I got mine from my local FLAPS (Friendly Local Auto Parts Store). If you can't find it, pick a guy there with gray hair to direct you to it

Bob Miles

[Rafe Hollister]

Mine is the top cover, so no linkage. Shifter comes out of tranny top. I'll check the number when I do the job. Thanks, you all made this simple.
"I'd explain it to you in a way that you could understand, but I don't have any crayons." Abraham Lincoln

[Rafe Hollister]

The Dana takes 2 quarts. How much does the trans & OD take? Will a gallon do it?

[Topper2011]

You can also get 90wt GL1 from your local True Value. I bought a 1 gallon jug for about $22. It should be enough. If you have a Twin Traction diff, you need the friction modifier.

[Rafe Hollister]

Tractor Supply is all out of all types of gear oil. Oreilly's and Auto zone can't get it (or don't know how). So tomorrow I try NAPA and TrueValue and Ace.
It does have some type of posi-traction, don't know which. What is a friction modifier and does it come in the oil or do I add it? Thanks for the help.

[rbisacca]

The Dana takes 2 quarts. How much does the trans & OD take? Will a gallon do it?

Yes. Trans & OD take about 2 qts.

[StudeRich]

Tractor Supply is all out of all types of gear oil. Oreilly's and Auto zone can't get it (or don't know how). So tomorrow I try NAPA and TrueValue and Ace.
It does have some type of posi-traction, don't know which. What is a friction modifier and does it come in the oil or do I add it? Thanks for the help.

A '56 Power Hawk would not originally have a Twin Traction Dana Axle, but it certainly COULD have been added from a later Stude.
Before buying the Friction modifier 4 OZ Bottle to add to the GL-5 at your Parts Store, I would check the Diff. to make sure.

If you "Feel" the Limited Slip Unit very close to the Fill/Check Plug opening it is a TT. The Standard Diff. "Case" would be farther back a inch or more.

[Rafe Hollister]

My car was modified quite a bit, bored 60 over (269?), cam, 9/1 compression, 3 on floor, etc.... I was told it had limited slip and can think I can feel it when accelerating out of a tight turn. I will double check when I open the fill plug.

[NCDave51]

Tractor Supply is all out of all types of gear oil. Oreilly's and Auto zone can't get it (or don't know how). So tomorrow I try NAPA and TrueValue and Ace.
It does have some type of posi-traction, don't know which. What is a friction modifier and does it come in the oil or do I add it? Thanks for the help.

I attended a tribology seminar for work in early 2019. Do you want to talk about head spinning - I have a bachelors in organic chemistry and when you’re amidst all these PhD‘s talking about chemisorption and boundary layers and all sorts of industry jargon, I was definitely in over my head.

In short, these are additives added to oil to give molecular-level reductions in coefficient of friction. In many cases they will bind to the working surfaces. On a larger scale, oils will use their viscosity to be able to handle heat and provide cushion between the parts, but because of this viscosity that can’t get into all the nooks and crannies. The additives will ensure that parts are protected or thoroughly under all extreme circumstances.

[Rafe Hollister]

I found a gallon 90w mineral gear oil at in stock (23 bucks). And also bought two quarts of GL5 with limited slip additive on sale for 6 bucks each. Thanks NAPA!