T90 / D18 rebuild questions

I can't keep oil in the tranny anymore. 2 to 3 days and it's empty It's time for a rebuild. Here's the particulars:

*I know nothing about how they work
*I know nothing about clutches and alignment
*I have a T90 mated to a SBC
*Can one guy do this himself? (me)
*I will be using Herms kits
*I am not sure I want to take this project on, but funds dictate that I will be doing this myself

 

Here's a good instruction site http://www.willystech.com/wt/T90RebuildGuide/RebuildVideo.htm
http://www.willystech.com/wt/T90RebuildGuide/T90rebuild.htm
http://www.willystech.com/wt/Model18TCase/Model18TransferCase.html
http://www.jeep-trucks.com/WOJP/TransferCase/Assembly2.html

I bought the Video and by the reviews, it's supposed to be good. I'll probably look at it if I get in trouble.

 

I just thought of something (and tell me if I'm not thinking this through)

My only problem with both the tranny and tcase is that they leak. Should I just buy the seals and gaskets, or break down and rebuild them?

 

Dennis,

I used Rick Stiver's guide for both. I just loaded his site(s) onto a CD rom and ran it on a cheap laptop on the work bench. (no connection in the garage...) Anyhow, it wasn't terrible, and you've got Basic Wrenching 101 behind you, so you'll do just fine. The more time you have the better, but you'll do fine.

A couple points....

Now is an excellent time to make the thing as leakproof as possible. Clean it really well, and flatten out the sheet metal so the gaskets seal well. Use aviation sealer. Worked for me.

The Novak intermediate shaft is a great investment. Just use some assembly lube so the O rings don't get chewed up. In fact, a little chamfering of the intermediate holes in the case would go a long way to helping get those O rings in place easier. (can you say Dremel Tool?)
Of course, do this BEFORE you finish cleaning the case.

Some good options with sealed bearings. Details on Rick's site.

The shim pack on the transfer case doesn't have to be several shims. One thick one will be easier to seal than several thinner ones. You may end up making one out of brass or aluminum, but I feel it's worth it.

You'll need a dial indicator. The Harbor Freight one is OK. Just get it with a magnetic base.

And final thought...There is nothing quite as sickening sounding as needle bearings hitting the bottom of the tranny case when you go to disassemble it. This is normal, take a deep breath, move forward. Welcome to the club......

 

Dennis, you'll have to take them pretty far apart to re-seal them at every point they leak. It may be just as easy to rebuild, you'll have to go through half the motions to just do the seals and gaskets anyway....

In short, if you take them out of the Jeep, might as well do it all!

 

Ditto on what Bill says. I just rebuilt my T90 and I went the sealed bearing route. I did a lot of research on it and can help with any questions regarding it. I also capped off the shift rail passages on the T90 cover, and I drilled and tapped it for a backup light switch.

With the Dana 18, definetly go for the Novak shaft. Herm sells it with his kit for an additional 20 bucks. And polish the shift rails where they protrude out of the case. This too will minimize leaks as it gives the seal a smooth surface to ride on. Also look into the double lip seal for the front and rear output shafts. Polish the output shafts too.

I got part numbers for the stuff I mentioned above that I can dig up. But do a search first. Many of the part numbers are already out there in prior discussions, and there are plenty of good tips to read also.

 

Thanks guys.

I just shot Herm an email. I want to talk to him before I purchase everything. We'll see how it goes.

 

A little advice, if things get to teadious for you or you are having trouble with a certain thing, walk away for a little while and write down where you stopped.
Since I do stuff similar for a living only a lot more critical, I'll give this piece of advice and it can't be over emphasized,Clean, Clean, Clean and Clean it again.
I rebuilt mine about 10 years ago now, my transfercase and my T14, it took longer to clean it for me than it did to assemble and set the bearing preload. Mine never leaked until I took it apart for Tellico to put the twinstick in, now its dripping out the front where the idler shaft is at. I think I have lost about a teaspoon in a month now, but thats Ok I added an xtra quart to the transmision and the transfercase to start with.

 

going against the grain here (surprised?)
If everything mechanically is okay (shifts okay, no noises than the norm), just replace the offending seal(s)
if your losing that much gear oil, sounds like t/case to me: front or rear ouput seal, bottom pan gasket, drain plug, etc.
T90 has very few places to leak: gasket between the trans/t-case, bearing retainer gasket and felt seal, and top cover.
heck, just for grins start tightening a few bolts, clean it all off, and drive it !
see what happens, it only costs you the time.

 

Sounds like a good plan.

 

I'll start there, Jim.

I just got off the phone with Herm (nice guy ). He explained things to me well enough where I'm not as worried about this. I know you guys will be there for me too. I just worry about things until I'm in the middle of them and realize it's not such a big deal

 

Wow, I thought I was the only one....

Jim does have a good plan. Find where it's leaking, and see if you can fix it without taking it out of the Jeep....Sometimes I skip over the simple things. Easy to do when they're not yours!

 

I get the feeling I'm going to have to go thru this also.

 

It's a piece of cake......tranny is very easy, no real special tools required and goes together (after a few days of cleaning, prepping and painting) in a few hours. Although I had never even seen a clutch, no problems there either (although my pilot bearing was a little snug until run a few miles).

The transfer case takes a little patience and a few tools. After putting everything back together and running it a few miles, my TC still leaks, but the only leaking on mine now is from the speedo connection and one of my overdrive gaskets (for some reason I didn't use RTV on that one). Both I will try to solve once I find the energy.

 

FWIW, I just got a D18 rebuild kit from Herm with the Novak shaft. It had the grooves for the O-rings in the shaft, but the O-rings were not on the shaft when I got it. When I asked Herm, he said that he usually can't install them with the O-ring anyway without chewing them up. Mine never leaked around the intermediate shaft to begin with, so I will probably put it in without the O-rings.

Jon

 

Jon, while you have it down to the case, why not chamfer the edges of the holes where the I-shaft goes? (be sure to clean away the shavings/dust when done before assembly...) With a tiny bit of a light chamfer and a bit of assembly lube, you should be able to get the O rings on intact. I did.

 

Mine from Herm didn't come with o-rings either. I went to True value and got the perfect size for it. Still applied a tiny bit of RTV and they went in perfect. No leakage from the int. shaft at all.