Over active brain

[fishnjim]

I couldn't search this, because one has to have 2 letters min., and type "A" only has one.  How crazy is that CLC?

My thinking is modern trans fluid in '50s hydramatics seem to leak, and caused me to wonder if related to the modern spec vs the original type A spec fluid?  I recall my trans guy telling me, it might leak if I rebuilt but never could pin him down.   I know they talk about backward compatibility, like brake fluid, but give me a break there.  Trans fluid is tough to contain as it is.   
My PS also calls for type A.   I put modern "anti-leak PS fluid" in and it leaked badly at the pump unit.   Trying new Dex/merc now and tightening up but trans has some seeps too.
Just a hunch/hypothesis at this point.   I've got some research to do to convince myself.   All these anti this or that additives could be seeking out things they shouldn't...like the outside!

[J. Gomez]

I couldn't search this, because one has to have 2 letters min., and type "A" only has one.  How crazy is that CLC?

My thinking is modern trans fluid in '50s hydramatics seem to leak, and caused me to wonder if related to the modern spec vs the original type A spec fluid?  I recall my trans guy telling me, it might leak if I rebuilt but never could pin him down.   I know they talk about backward compatibility, like brake fluid, but give me a break there.  Trans fluid is tough to contain as it is.   
My PS also calls for type A.   I put modern "anti-leak PS fluid" in and it leaked badly at the pump unit.   Trying new Dex/merc now and tightening up but trans has some seeps too.
Just a hunch/hypothesis at this point.   I've got some research to do to convince myself.   All these anti this or that additives could be seeking out things they shouldn't...like the outside!

Jim,

If you want to learn more about ATF fluids and the ins and outs of them may I suggest viewing the YouTube videos from WeberAuto. These are very long so just grab a long and strong cup of coffee.   

https://www.youtube.com/playlist?list=PLIn3FrDiB1lwMQK1BilB7FraTpyf3TJQ2

You can also do some research from the Wikipedia on these fluids.

https://en.wikipedia.org/wiki/DEXRON

https://en.wikipedia.org/wiki/Automatic_transmission_fluid

Newer ATF are specifically designed for close transmissions with minimal case seals to avoid leaks due to lower viscosity versus the older fluids type with a higher viscosity designed for older transmission with several seals and different gears, clutch material, etc. This is just my 100K foot level view from my limited research.

You could also read (access would be required to read this material);

JOURNAL ARTICLE
Automatic Transmission Fluid Viscosity Requirements
M. L. Haviland and E. D. Davison
SAE Transactions
Vol. 80, SECTION 4: Papers 710619â€"710867 (1971)

Good luck..!

[savemy67]

Hello Jim,

I haven't done an exhaustive investigation, but most sources say Dexron VI is backwards compatible to Dexron III.  This gets us back to about 1967.  Some sources say Dexron III is backwards compatible to ATF type A.  This gets us back to about 1949.  All this applies to GM Hydra-Matic transmissions.

From 1940 through the end of WWII, the Hydra-Matics used bronze friction plates in wet clutch drums.  1946 and later transmissions used the more familiar paper friction plates.  Until the switch pitch TH400 in 1965, there were no electrical components within the transmission case.  Today of course there are lots of electrical components and wires inside the case of a transmission.  Imagine what sort of changes the fluid had to accommodate over the course of 50 years.

Working at the .001" and .0001" level, I tend to think a well designed seal should be water-tight - and water is much thinner than transmission fluid.  If a transmission seeps after decades of use, the seals and gaskets may no longer be up to the task regardless of which fluid is used.  I encourage you to read the links provided by Jose.

Respectfully submitted,

Christopher Winter

[fishnjim]

Well, I made my point, never jump to conclusions about these things as we so often do.
I see this in most posts.   Already decided what's wrong, but then asking for help when the facts don't line up or knowledge is lacking.    I'm guilty too, just making a point to learn from.
Clearly looks like the gaskets that came in the rebuild kit were poor quality.   One side was seeping.   Nice thing about red trans fluid v clear, you can sure tell if it leaks, but messy.
I vaguely remember, when I did the rebuild, I wasn't happy with the reservoir gaskets.  (Trust your instincts!   Wait, don't do it.)   
The holes are supposed to be two different sizes, and they were the same and maybe thickness wasn't so accurate and durometer was off.   I'll have to hunt up the old ones.   These are already stiff and cracking.   I won't say who the vendor was, because I don't do that.   I'll take it up with them directly.
I'm going to tear down the pump side since it stopped working, may have a stuck vane or something.   Just might be a piece of rubber somewhere it shouldn't but I'll reserve judgement.   Hope, I don't have to tear into steering gear.   
Now it's possible the fluid was incompatible, but I suspect more likely the gasket material was wrong.   Cheapo from half way around the world?   So many grade of materials, tough to get it right if not trained know what to ask for.   
Hint: the never seize on the pulley shaft made taking off simple, vs the last time it was stuck fast for 50+ years and caused damage to the pulley getting it off.   

[fishnjim]

Old man made a boo boo, too.   Put flow valve plunger in backerds.   No excuses.
I hope that's it, but won't know til I make some gaskets and put back together but makes more sense now.   One vane was a bit temperamental but I didn't see any trash.   Flushed with some brake cleaner and teflon lube for funzies.
I see there's cork gaskets in the kits now.   It had rubber ones on it, which I couldn't find yet.   I got rubber ones in kit - 2 alike.
I ordered a OEM set for another brand that's out there, so I have some patterns.   But takes two different gaskets.   Yeah, you can make the bigger side fit and save a buck, but that's not nice kit suppliers...