I have a 57 Super 88 371 J2. Have 55 slant pan hydramatic trans. It appears to me that the drive shaft may be a little short for that trans. I have adjusted the center carrier bearing as far forward as it will go and I’m not sure the yoke is in far enough. Have 3” of output shaft into the yoke and only 1” of yoke past the rear seal. The attached diagram explains it better.
Am I ok like this?
Do I need to have the front drive shaft section lengthened?
Appreciate any feedback.

 

You are probably going to need to have the driveshaft lengthened. On a 1955 hydramatic the actual rear seal is inside the tailshaft housing. What you see at the end of the transmission is just a dustshield. If you don't get the yoke up inside the seal you are going to have a significant leak. My 54 actually has a 55 engine and transmission in it. This was discovered when I had the transmission rebuilt. This was a change they made in 55 and I believe continued through 57. The seal went bad after my transmission was rebuilt and they had to pull the transmission and pull the tailshaft housing off to replace the dang seal.

 

Thanks red… should it be lengthened so the yoke slides on until it “bottoms out” or leave a small amount of gap?

 

I would leave a small gap before it bottoms out. I am thinking about 1/4 inch. The main thing is it goes all the way through the seal.

 

So the seal in the pic below is what your referring to as the dust seal?

 

That looks like e neoprem seal. The seal I have there has a felt center. That looks more like a seal that will actually hold fluid in. Interesting.

 

I have little input here other than if I read this correctly this slant pan is new to this car? In 56 the slant pan and Jet-a-way came in both models 88 and super and I don't remember any difference in transmission length or drive shaft from one transmission to another. I would think the swap should work without modification. They should be the same with a 57 I would think. Someone correct me if I an wrong..... Tedd

 

Tedd - Thanks for the input. Yes the slant pan is new the car. It is a Pontiac 1955 Hydramatic.

 

Hmm, I don't think( could be wrong on this) but the Pontiac is the same transmission as a slant pan but doesn't have a actual slant pan. Will it clear the X frame with out touching? And will it bolt up the same. Here again I'm going from memory from along time ago and I'm thinking early Cadillac had the same bolt pattern but not Pontiac. Someone correct me if I'm wrong on this.... Tedd

 

I don't know anything about the 55 Pontiac hydra-matic. I don't know if the rear seal was like a 55 Olds not not.