1941 Series 63 Hydra-Matic Fluid leak

[J. Russo]

I have a transmission fluid leak where the driveshaft attaches to the transmission. It's not a severe leak, but I would like to fix it.

Any advice on possible causes and how to resolve is greatly appreciated.

Thank you

[Omarine]

Sounds like the tailshaft seal. It's inexpensive, will need a slap hammer to get the old one out. Can be done on the car, although ive never attempted it.

Cheers

[J. Russo]

I would appreciate any instructions on how to remove and replace this rear seal. The seal is available and inexpensive. I'm not sure of the degree of difficulty. I realize I'd have to drain the transmission fluid. I have a couple of Hydra-Matic shop manuals, but they don't seem to address the removal and replacement of this rear seal.

Thank you

[signart]

Easy-peasy. You won't lose much fluid, especially if it's already low. Won't lose any if you set the car up on jack
stands level or slightly higher in back. There are more than a couple ways to do this, some use a slide hammer, but not necessary if you don't have one.
Go ahead and buy the seal and study how it is made. Remove the drive shaft. Take an old worn or broken screwdriver or pick up a cheap wuhan  screwdriver. Grind or file the tip of one side to make a sharp chisel like edge.
Take a hammer and tap the blade between the lip of the old seal and the tail shaft housing. After it gets under the lip of the seal, tilt the handle slightly toward the rear of the car and continue to drive the blade into the old seal and perforate it slightly. Then push the handle forward and pry the old seal away from the tail shaft. Repeat this on the opposite side of the seal and continue around the perimeter until you can grasp it with channel lock pliers and pull it free. Don't worry about distortion of the old seal. Takes longer to type this than to remove the seal

Check the movement in the splined tail shaft. If excessive, you may have a worn bushing that you might or might not want to tackle at this time.
Clean the area inside the tail shaft housing and coat the area where the seal will seat with a small amount of grease. Grease this area of the new seal and the inside rubber part of the seal before installing to prevent damage when inserting the yoke from the drive shaft.
Start the new seal into the housing and press in using your thumbs to get it aligned perfectly. Try to find a socket to fit slightly smaller than the seal lip and carefully tap the seal in, checking alignment with each tap until it seats fully. You can do this with a rubber hammer or such, but keep the seal in perfect alignment as it goes in is the most important.
Check the yoke of your drive shaft for a wear ring or damage as this will shorten the life of seal and may not seal at all until repaired or replaced. A worn bushing on the tail shaft will shorten the life of the seal also, but probably not so immediate.
Good Luck.       
   

[J. Russo]

Art,

Thank you for the instructions. I attached a photo of a seal puller I used to remove my rear axle seals. Based on your instructions it sounds like I can use the same tool. Let me know what you think.

Does the bushing you mention simply slide into the tail shaft before I install the new seal?

[signart]

That tool may work if you can work around the splined tail shaft which protrudes beyond the housing. When used on an axle seal, the axle is removed, so there is no interference.

I am not familiar with your particular model transmission, so if the tail shaft housing is removable, I would remove it and use your tool to take out the seal. You could then remove that bushing, but it is pressed in and would require some special tools or shade tree substitutes for removal and replacement. If the tail shaft housing is easily removable, you might want to buy the correct bushing and take the housing to a shop and have it pressed out/in. This way you have less risk damaging the housing or the new bushing.

I have changed a few in 350/400 turbos of the '60s, but there is a slot provided in the tail shaft for bushing removal and is pretty straight forward for me. There is only four bolts on the '60's transmission for the housing, but removal is not always necessary here. The design of the seal hadn't changed much for decades.

This bushing is what your yoke rides on and replacement could deliver a smoother transfer of power if it is worn badly.

You may want to just change the seal and be done. If you decide to change the bushing later, you will have to do the seal again.

[wheikkila]

It will take a bushing driver to get the bushing out. That can only be done if you remove the tail housing. Check with your local parts store to see if they rent them or have a free loaner program. Or just change the seal and see if it fixes the leak.
            Thanks wayne

[signart]

You can remove the bushing from a more modern trans without removing the tail shaft by using a tool like this. Might work on a '41.  Cost anywhere from $100 to over $300. I made my own tool for my old (starts with a C, but don't end with a c)
Don't know if you can rent one to fit a vintage Caddy, but you would have to have the bushing in hand to check fit.