Pre-war (up to 1942) 1941 Hydra-Matic Transmission Yoke

[Joe G 12138]

      RTV will not seal splines. Any oil before or after installation will work it loose and it can go places. I've had very good luck with "Rectorseal" for the last few years. This or similar stuff should be available at hardware store or plumbing supply stores. It is made for petroleum or fuel piping. The hardest part of any job is the preparation. In this case, you need to get the oil and RTV off of the spines and grooves in the yoke after they are already wet for it do do its best, but being for petroleum use it is somewhat forgiving. But the other part to be aware of is the parts that need lubrication (outer surface of yoke and actual seal surface) need a coating of grease or lubrication when assembled. It's tricky to achieve both goals at once on a "wet" installation.
      Another thing that sometimes helps with stubborn sealing is use a copper washer under the yoke bolt head. Another hardware store item; they usually have an assortment to pick through. I guess I picked that up from working on the German cars....They love copper washers and "O" rings!

[Daryl Chesterman]

I noticed in this picture from post #26, that the end of the splined shaft looks like someone has beat on it with a hammer or something else, thus there is not a smooth sealing surface for the inside of the yoke to seal against.

https://forums.cadillaclasalle.club/index.php?action=dlattach;fs=73948;attach=215659

You might want to examine the inside end of the splined yoke to be sure that surface has no foreign material.  Since the lip of the seal on the outside of the yoke seals that surface, the only other place for a leak is where the inside end of the yoke seats against the end of the splined shaft.  When reassembling, I would place a small bead of ATF resistant sealer on the end of the shaft, lubricate the lip of the housing seal and the corresponding surface of the yoke, then install the yoke and torque the bolt to specs.

Daryl Chesterman

[J. Russo]

I wanted to provide information from the manufacturer of SKF speedi-sleeves related to tail shaft oil seal 15142. There are multiple (5) sleeve options depending on the measurements of your yoke. 99147 is an option but not in the photo they provided.

It would depend on how worn your shaft is. The 99147 will work on a shaft size from 1.496" to 1.490", and will work with the 15142 seal. If your shaft is 1.497"+ then you would want to use the 99149, or any of the four listed below. These will all work with the 15142 seal.

[J. Russo]

I've been out of pocket for a while and wasn't able to check my work after I finished putting everything back together.

A lot of things were discussed on this topic and I'll summarize what I did.

I had to make a couple attempts at replacing my tailshaft oil seal. I first used a driver to tap the seal as far as it would go into the tailshaft. I also installed a Speedi-sleeve over the grooved part of the yoke. The seal made contact with the Speedi-sleeve just fine. This didn't work for me as the tailshaft still leaked.

I have 2 Hydra-matic shop manuals. One is for a 1941 Cadillac. The other manual is for a 1946 GM Hydra-matic. My 1946 manual is missing the cover. It only mentions Oldsmobile in the manual.

My 1941 manual makes no mention of installing the tail shaft oil seal or what seal driver to use.

The 1946 manual mentions using Kent Moore tool J-1354 to install the oil seal into the tailshaft. This tool only drives the seal into the tailshaft 1/4 inch. I found the tool on Ebay and decided to use it on my Hydra-matic. The seal made contact with the unblemished part of the yoke in this position.

I also used RectorSeal Tru-Blu on the splines of the tailshaft and the yoke.

After about 40 miles of driving, the results look positive compared to what I had before. There is no leaking from the yoke at all. There does appear to be a hanging drip of fluid at the very end of my tailshaft that seems to be very minimal. It is not a frequent constant drip. I will continue to monitor.

Thanks to everyone for your input and advice. It is much appreciated.