1956 vs 1957 Hydramatic trans question??

[DTBass]

Does anyone know the difference between these transmissions.  I have a 1957 Cadillac trans that needs some type of coupler behind the torque converter.  My friend has a 1956 Cadullac trans that looks similar to mine but I'm not sure if it is the same on the inside.  He said I could use it for parts.  Thanks.

[dplotkin]

The 56 is a one year only tail shaft, and maybe case. The 57 innards are the same (with some improvements) as the 56. Both are "controlled coupling" Hydra-Matics.

Dan

[J. Gomez]

Douglas,

You will need to check the tag on the 1956 and see if it is a C56, CE56 or A56 (75 or CC) same for your 1957 C57 or CE57. There are parts that would interchange between these while others are year specific.

Behind the torus assembly is the front unit coupling are you in need of the complete unit or other parts? If you know which part(s) you need you can reference the MPL if they are interchangeable.

I could not attach a file as reference for the front coupling parts acquisition do to server errors; let me know if I should send it to you PM.

Good luck..!

[DTBass]

Thanks guys.  The tag on the 1957 reads C 57 and the tag on the 1956 reads C 56.  The transmission guy is the one who showed me the part in question that is behind the torque converter and has 4 tangs protruding from it.  The tangs were like 50 percent worn out.  He said he could get a replacement but told me it would very expensive maybe 400.00, so knowing that I have other parts cars available asked me if I could find the part or another trans that maybe we could use for parts.  I'll bring him this C 56 one and see what he says, thanks again.  Doug

[dplotkin]

I don't know where you are, but I know it helps to have a transmission guy who is familiar with the controlled coupling Hydra-Matic. John Poluso in Boston is such a fellow. He did my 56, which had your problem + a smoked reverse cone clutch. John knows old transmssions. (617) 327-2120.

Dan

[Roger Zimmermann]

There is a difference at the front unit coupling: early '56 cars had tangs at the driven shaft, later cars have a splined end; with the splined end, the part is the same for 57. The splined end is reliable, the tang shaft not, it can break; I saw it on an early '56 transmission.

[Doug Houston]

I had my first '56 Cadillac in 1958, through around 1956. I went through all of that ballet with the "Dump-and-fill" clutch that all of you speak of.  One of the big changes was changing the 4 tangs to a splined shaft. It wasn't cheap then, so now.....hoo, boy!!

I now have my second '56 convertible, and it has a very low mileage on it, which suggests hat it has the original transmission. There were lots of changes made to that transmission, and it was never straightened out until 1958. For the '56-57 models, the best controlled coupling transmission will be a '58 transmission, with a '56 tail housing and shaft on it. That gives you the rear pump for push starts, which was dropped in 1959.

In one of the Cadillac parts books (1961, I believe), Cadillac had a replacement transmission shown for the 1956 and 1957 models. It was a totally new transmission that could be bought, and completely replaced the original transmission.

One of our members in Texas has also installed a Turbo Hydramatic 400 transmission in his '60 Cadillac. I've toyed with that idea for my current '56.