All transmission guys, I have an issue.

First off, I'll start this by stating that I know enough about transmissions to get myself into a lot of trouble. I'll chalk it up to when I was a teen, my father told me never trust anything that bleeds red, women or automatic transmissions, haha. Maybe thats why I never learned. At any rate, I have a 74 500 Caddy with the long shaft th400 in my 40 Chevy pickup. When I first got it built and even after its first drive I had no leaks. I relocated to Ohio from Texas by dolly, and I DID remove the driveshaft prior. Once in Ohio I reinstalled the shaft and ever since It has been leaking fluid from the tail shaft. I just ***umed that I may have pinched the pinion seal when putting the driveshaft back. I replaced that and it is still leaking. Here is the thing though, it appears to be coming out of the center of the slip yoke, and not out of the seal. A friend of mine said maybe I had the wrong style yoke that is shouldn't be open, but closed in center, thats why it was leaking through the center. Thats makes zero sense to me because when first put together it did not leak a drop. The trans did sit a long time before I got it. I put a shift kit, new modulator valve, new pinion seal, and stall converter in during build process. The motor/trans have less than 100 miles on it since build. I don't know if that information is relevant or not, but guys, I could really use some advise so I can start driving the wheels off. Thanks ahead of time.

-DMFB

 

there must have been a seal or sealant in the yoke that fell out when you removed it.

 

Don't the yolks have a plug in them, like a freeze plug?

 

There was just a thread on that today. Search weep

It said there is an O ring on the mainshaft, if it has a weep hole type yoke. It said some mainshafts do not have a groove for the o-ring, and those must use a closed yoke.

 

The caddy trans should have the O ring on it, iirc.

Could have been cut or something when you reinstalled the driveshaft.

I'd pull the tailhousing off and look at the output shaft, install or replace the O ring if there's a groove for it.

If there never was an O ring, it's possible that the splines/yoke had grease on them that kept it from leaking at first, but the ATF washed it off the splines and now it's leaking.

 

Weld the hole closed.

 

Thats some great info. I guess tomorrow night I will be pulling the tail shaft off and taking a look.