Rebuilt C6, Leaking Around Output Yoke

[colnago]

Long story short, I rebuilt my 352 engine and C6 transmission. I'm in the process of getting them installed, although both of them are sitting in the truck at this point. I connected all of the plumbing on the tranny, and filled it yesterday (one quart in the TC, 11 quarts in the tranny). This morning, I noticed a puddle under the truck. When I got home, I found that it was leaking around the output yoke (bolt-on yoke, not a slip yoke). I installed a new rear seal. I applied a small amount of tranny fluid to the seal before installing the yoke, and I used a light coating of Permatex around the seal when I installed it. Any idea what's up, or what I can do?

Joseph

[DuckRyder]

What did the sealing surface on the yoke look like?

How long has it been sitting?

I might be tempted to give it a short run and get it up to temperature to see how bad it was leaking.

[colnago]

The yoke surface looked fine. No gauling or scratching. It's not show-room fresh; it came out of a '71, but I didn't notice any imperfections or issues. Pre-rebuild, it's probably been sitting ~5 years; post-rebuild, it may have been 3 months.

I should have everything hooked up this weekend. I am also thinking that she may just want to stretch her muscles a bit, and then I can check again for leaks. I really don't feel too enthused about draining the tranny, and putting in a new, new seal. That's why I replaced the seal in the first place! Most likely, the seal itself is fine, but I need to take some emery cloth to the yoke. Grrr!

Joseph

[colnago]

I think my rear seal isn't leaking after all. I drove about 40 miles yesterday, and don't seem to have a puddle on the driveway. Is it common for a new/rebuilt tranny to "seal up" after being exercised a bit? My theory is that it had a chance to come to operating temps, and the seal itself had the chance to wipe off any grease/dirt that I missed during assembly, but I'm new to this.

Joseph