Tail Shaft Seal-Rear Drive Shaft Length

[clarkchriston]

I have a TH350C and having some issues with the drive shaft tail shaft seal. The truck has been a garage project for a couple years and now we have it done and finally driving. The engine is a 305 mated to the Turbo 350 with torque converter that we got with the truck, so I can't vouch everything was done properly. Local mechanic did the once over and the motor runs good, and tranny shifts great, just having some leaking issues.

It never leaked from the rear main seal while sitting in the garage, but after taking it out a few times we noticed the drip and decided to replace the Tail Shaft seal. The main problem I had was trying to remove the Drive shaft. We were able to get it off but there is little to no play at all and had to carefully remove the u-joint bearings to get it off. Part of the old output shaft seal separated, with half of coming off attached (compressed) on the slip yoke. The other part of the old seal was a real bear to get out but we finally got it off, replaced with the new seal and barely got the drive shaft back on.


We did not replace the Tail Shaft Bearing (I know pretty dumb) so that may be part of the problem. We will be replacing that along with a new seal. The main issue is it leaks worse now than it did before we replaced it. I'm wondering if the drive shaft is just to long and because there is no play, the U-Joint (on the slip yoke) is bottoming out on the seal and basically acting as a slide hammer causing it to fail. I also read (after the fact) that some use grease when setting the seal which we did not do. Any recommendations would be greatly appreciated.