1950s Another ill transmission

[Roger Zimmermann]

Last week, I got a 1956 Cadillac transmission to overhaul as there was no second and 4th gear. A clear case for the front unit coupling leaking was my first thinking. Then, I began the disassembly.
Oh boy! I never saw such a black oil which was smelling real bad.



Most hubs from the toruses had deep markings;



A copious amount of silicone was used by the previous rebuilder...after another one used black silicone! I will most probably find some in the valve body...
When I removed the torus cover assembly, I noticed that one rebuilder had a fight with a massive oil leak as this element was repared using silver solder. Not good looking, but efficient as I found no leak after testing.



Strange enough, the clutches were is a good shape; this was not the reason for the black oil. The Ah, Ah! moment came when I disassembled the front unit coupling. Large elements from the aluminum flange were gone:



and the driven torus assembly was damaged too: the small "ears" were flat and a strip of steel was missing:



The black oil was the result of the destroyed cover and the deep scratches were done by the residues going everywhere. As I found other strange scratchings, this transmission had an hard life.

Fortunately, I had some good used parts and, the ones I don't have will come from the US.

How long hard parts will be available for those transmissions? Sure, the grooves at the hubs could be repaired by turning them and inserting a sleeve. This will be necessary when all the good parts are gone.

[TJ Hopland]

So what do you think caused that damage?  I don't know this model well enough to tell what was supposed to be going on there. 

The shop that I used when I did a 57 a few years back said hard parts for all this earlier stuff have been a big problem for years.  They said till about 20 years ago you may not have liked the prices but you could always find the parts if you really needed them.  Now they said many times for many parts you just can't find them when you need them and when they do come up they are so expensive most people can't afford to buy them just to have in stock.

They also said its pretty rare these days to get an auto transmission in that doesn't have hard parts damage because people keep running them till they fail. Its kinda like pinging/detonation by the time you hear or feel it its way to late and damage has happened.  They said around 20 years is still about the lifespan of the soft parts that let them work correctly so if you refresh them around every 20 years you can get away with just the soft parts kit which tend to still be available and reasonably priced.   

[bcroe]

They said around 20 years is still about the lifespan of the soft parts that let them work correctly so if you refresh them around every 20 years you can get away with just the soft parts kit which tend to still be available and reasonably priced.   

My experience as well, refresh the soft parts after
a couple decades, might save your hard parts by
avoiding a bad (black and smelly) failure like that
for a long time.  Bruce Roe

[Roger Zimmermann]

So what do you think caused that damage?  I don't know this model well enough to tell what was supposed to be going on there. 

Hard to tell. Anyway, the front unit coupling is the weak element in those tranmissions. Depending how heavy the foot from the driver is, especially with the quick down, the aluminum cover has an hard life. There should be no relative rotation between cover and driven torus asssembly; the cover is held with four small points. Earlier transmissions had only two points, only suitable for a little lady!
I'm attaching pictures from the earlier two points attachment and a good cover.

[TJ Hopland]

So those parts are more or less supposed to be one unit?

[Roger Zimmermann]

Yes. It's indeed a second fluid coupling for the second and fourth speed.

[1959Fleetwood]

Hello Roger, Nice posting ! As a experienced transmission rebuilder is see a lot of the problems in my shop that you describe. Right now i do have a 1960 Hydra-matic on my bench with burned clutch and steel plates and a broken
rear clutch release spring witch is a common failure. Also i found a 2"inch piece of the large snap ring that holds the neutral clutch drum and center support locked in the main case. Well, the strange thing is that all the remaining snap rings
including that large snap ring in the transmission were unbroken  No clue how i ended up between the front unit coupling and the front oil pump without damaging any part or making noise.
Also the aluminium cover of the front unit coupling is, as you describe, a common failure and prone to broken of pieces. This part is in most cases the cause of not having a second or fourth gear. In my humble opinion this a design fault to begin with. I think that the 1941 to 1955 transmissions are a far better design.

Keep up the good work !
Sincerely, Matern harmsel
CLC 15331

[Roger Zimmermann]

The oil had certainly a bad odor! On the 59-63 transmissions, that release spring is indeed often broken.
Sometimes, I'm wondering how a transmission could still have some functions even with strange damages...
By the way, some years ago I sent to the Netherlands a tool made in brass to check the front unit play. Did I send it to you?