ZF Leak

...I seal gearboxes at work. We use silicone. We make sure the surface is cleaned of all oil, using 'laquer Thinner'...

Befor installing the seal and housing assembly again, look athe area where the housing seats. You should see the edge of a bearing there also. If not then you have found the leak.
If that input shaft "nose" support bearing is missing, then the shaft will "whip" around slightly and the seal does not stand a chance of keeping the oil in the box.
How can the bearing be missing??? Simple...ZF (unfortunately) made the bore for this bearing with no shoulder or stop for the bearing. Therefore the bearing can (with a little vibration) walk right inside the box and just be floating on the input shaft.
I have found this more times than I can count.
Best regards,
Guitar Man

Les,

is there a fix for this? such as using a Loctite product to secure the bearring in its bore?

George

Yep! When I resealed my ZF that was one of the first things I checked http://www.panteraplace.com/page10.htm My bearing was in the correct position but they can move if you have clutch chatter (unlikely on Panteras) or a misaligned bellhousing.

Mike

Mike is correct. I usually install them with Loc-Tite stud and bearing mount so the chance of movement is greatly reduced.
The problem here is getting the bearing back into the case with the input shaft in place !!(this is the hard way !!!!) By removing the bottom cover you can sometimes , with great patience, coerce the bearing back into place....... otherwise you need to pull the cluster housing and assembly for free access.

Les