T90J To GM Adapter Leak

Well dang. I’ve been cruising around town in my nicely rebuilt 67 CJ5 but started noticing massive puddles of gear oil underneath. I’m used to a few drops here and there, but this was excessive. I thought I was diligent sealing it up, but I missed some things, clearly. However…no leak from shims and parking brake! Not one to leave things alone, I pulled the transmission and t case tonight.

So here’s what I found: oil is leaking from the front sealed bearing out between the transmission and Novak adapter. Adapter has a lip seal to hold oil, but I guess there was too much.

I installed the plugs that came from the kit in the weep hole and in the shaft. Do I unplug the weep hole? Any sealant needed between adapter and tcase? I’m using the traditional paper gasket but the screw holes from the original input shaft sleeve are wide open as well. Plug them? Ugh.

 

If I'm reading correctly your input bearing is sealed at the time of the rebuild. The adapter is also sealed and the oil galley in the case is sealed creating a sealed pocket with the exception of the oil galleys in the input shaft. Those oil galleys connect to the crossdrilled holes in the gear so as the gears mesh it pumps oil into the needle bearings and your sealed front bearing cap.

What I would do is drill and tap the holes in the shaft in front of the bearing. Then insert some set screws and pin the hole in to keep them in.

Side note, that sealed bearing is for non-sealed bearing retainers so you can pull the seals off the bearing and unplug the case if the nose seal is ok.

 

Thanks! The hole in the shaft is already plugged with rubber plugs supplied by Novak. And there is a plug in the bottom return hole. I’m thinking about simply removing the bottom plug so the oil returns back to the transmission. But I still don’t know what to do about the original three holes that mounted the sleeve over the input shaft. Plug? Cover with a gasket?

I’m considering a small bead of rtv where the adapter mates with the tcase.

 

I put a thin film of RTV on the gasket. Your sealing everything up there so it can't hurt to go heavy. Put some never ever let loose thread locker on some shallow set screws for the threaded holes. Pin (hammer and punch at the edge of the hole) the case so the set screw can't go past the case into the gears.