I need to know if you have to drain the transmission fluid in order to change the seal. Haynes says drain it and coat the outside of the seal with sealant. I know the pinion seal doesnt require any sealant so why should this one? Just replaced my rear end, exhaust and rebuilt my suspension. Oh, its a
700R4 tranny

 

You don't have to drain the trans to do the seal. I usually just put a small catch can under the tailshaft. A little will come out, but it's not much. As far as sealant goes, I always smear a really thin amount around the outer, metal part of the seal before tapping it in. It isn't really critical to do it, but it is good, added insurance from having a small leak. I always do it on pinion seals too for the same reason. The slightest nick or gouge in the housing seal bore can cause a small leak, so that's why they tell you to use a little silicone. The most critical thing you want to make sure to do on an output shaft seal, or pinion seal, is to smear a little motor oil or trans fluid on the rubber lip part of the seal. If you install it dry, it can burn the rubber lip when the yoke spins, which will cause it to leak all over again. I just replaced the harmonic balancer/timing cover seal on my motor, and I used the same method on that one too. No leaks at all.

 

i would just drain it so you can replace the fluid.. if your seal needs replacement, i'll bet your fluid does too..

trust me, it wont hurt either..