[55 BELAIR]

I put a 700R4 in my 55 last year(had 350 turbo). I have a problem now with the rear seal leaking. I replaced it with a new one but it still leaks. It leaks quite a bit when sitting still with out the engine running. I get a good size puddle after a few days. Does any one have any ideas as to what could be causing this leaks. Could the yoke have anything to do with this?

[Chazmac]

You could have a yoke problem. Check the polished area of the yoke. It must be smooth and even, no wear in the bushing area. If the yoke is worn, replace it and the tailshaft bushing. Also check to see if the yoke has a rust area (even if it was polished) where the seal surface is riding. This will cause the seal to leak past the rust. Check to see if the yoke has a breather hole drilled in the center of the welch plug in front of the U-joint. If so, it needs to be welded shut, or get a yoke seal sleeve from a trans shop. These were commonly used in 2wd trucks and vans.

[55 BELAIR]

That sounds very possible. It didn't take long to start leaking again after I put the new seal in. Almost immediately. I knew a heck of a lot more about these old cars when I was a teenager. I just started back on them three years ago and I realize that I forgot a lot in 40 years. Thanks for your advise!