D20 Front Output Shaft Bearing

Went for a quick drive today and noticed some "new" vibration on acceleration that steadily got worse the closer I got to home. Crawled under and found that my D20 front output shaft bearing is shot. I replaced my rear output bearing about 8 months ago with no problems, but I just wanted to ask someone who knows more about it than me. What am I getting into? I can't find walk-through type instructions, plus from what I read the output/input shafts might separate and things might drop into the pan? Also I hear the bearing itself can be a bear to pull off of the shaft-does anyone have any tricks to easily pull it? I am looking to not pull the t-case... Thanks in advance for any help!

 

If both sets of output bearings have failed this close together you should really pull the transfer case and inspect/rebuild it. This tells me that either this thing has been used hard, has lots of miles on it, or has had foreign material run through the bearings.
Personally, I'd pull the transfer case. It's much easier to do on the bench, especially the front output bearings which must be shimmed. The frustration saved alone is worth pulling it. A FSM (Factory Service Manual) is worth its weight in gold for this kind of stuff and most on this board highly recommend purchasing one.

 

I have the same problem. When you say shimmed do you mean forward and backwards on the output shaft or a jiffy sleeve to protect the new seal ?

 

ncikmil- That's what I was afraid of. When I replaced the rear bearing, everything looked great and the fluid in it was clear. I guess I'll probably just pull it and rebuild it. I was under the impression that the T-18 was "bulletproof" but should I try and upgrade some parts while I have it torn apart? I'm turning it with a relatively 'hot' Chevy 327, although I would think that it could easily handle it with no problem at all. And where can I get a FSM that describes the T-18a? Does the Haynes manual cover in the T-18 in depth?

 

Actually, the FSM posted online for the '74 has a section on rebuilding the manual trans...and it uses the T-18 in the demonstration. Chapter 6 I believe.

http://oljeep.com/edge_74_tsm.html

 

The front output shaft has shims on the back side underneath the 4 bolt cover. This controls end play/clearance of the bearings for the front output shaft. Too tight and the bearings burn up, too much and they will beat themselves to death in fairly short order. Very important to set them correctly. The T-18 transmission really doesn't enter in to the end play of the outputs of the transfer case here.

 

Thanks for that info nickmil. I can see how it would be easier to just pull the transfer case out like you posted earlier.

 

Just a quick question on the front output shaft rear shim cover.
There were no gasket in my kit, and it didn't have one on either, so I suppose there shouldn't be one.
After assembly, mine is leaking oil badly, so could I use a little RTV on there?

 

Okkie,
No gasket used there. I put a thin coat of sealer in between the shims and between the shims and case and shims and cover. I also put a bit on the threads of the bolts to keep leaks from happening there.

 

Thanks Nickmil.
I will do that and just recheck the endplay afterwards.