Too far gone? (T-90 teardown and rebuild)

Hi all,

I just got my transmission separated from the transfer case and got to take a good look at it. My jeep was parked for many years, and it appears that the gasket on the top didn't do a great job keeping the moisture out because there is a fair amount of rust in there. However, it seems like I can chip the rust off of the gears fairly easily. I have never taken a transmission (or anything like it) apart and I have no baseline on whether or not the gears are too far gone to restore and clean or what I should replace. My grandfather doesn't recall there being any issues with the transmission when it was parked, so I am under the impression that everything is in good shape besides the rust. I have a picture of the inside (viewer discretion advised). Any tips on removing the rust without damaging anything?

Any advise would be appreciated! Thanks!

-Alex

Attachment 9611

The surface rust to the gears isn't the big issue. It's the rust on the idler shafts that eat the bushings out of the gears, and cause issues like you are seeing. If you do not feel comfortable, you may can check around to a repetable transmission shop that can shoot you a quote that isn't too bad on the wallet, since you have the transmission brought in and set on the counter.

I wouldn't say its "too far gone" until its apart and well inspected. Like gm said, a little surface rust in the right places wont hurt. In the bearing areas it can and, if it is too bad it will. I would not even try to run that transmission without a good inspection, tear down and an overhaul. You can count on all new bearings gaskets and seals as a minimum. The hard parts are expensive so any gears and parts that can be salvaged are the way to go. Or you could trade it on a rebuilt unit as a core at KW or some shops that may have an inventory.

Alex like gm and bmorgil stated it’s not as bad as it looks, but most definitely it needs taken apart and looked at inside.
I used Rick Stivers videos on YouTube to walk me through the the tear down and reassembling of mine, you have the worst part behind you the removal and separating it from the transfer case.
It’s actually pretty simple, but don’t skimp on seals, bearings, shims and or any bushings in doubt. The old saying when I’m doubt replace it!!!
I took mine all apart and set aside the pieces parts in doubt, ordered those and while they were on the way cleaned everything up and painted the case.

If in fact you want to tackle it yourself, if not bmorgil has the best solution find a local shop or use it for a good core at KW.

From a financial standpoint, I'd rather not pay someone to do something that I'm capable of doing. I think I've watched Rick Stivers video 20 times in the last 2 weeks! It's a great resource! I disassembled everything yesterday, and I was fairly disappointed to find that everything was VERY rusted at the bottom (gears rusted together, rusty sludge with chunks of rust at the bottom). It seems like the rust will flake off with a little work, but I don't know enough to know what I should reuse and what needs to be replaced. I saw that Novak offers a kit for the T90 that has most of the components that I would replace regardless (seals, gaskets, etc), so I was contemplating buying that and then seeing what else is in such bad shape it would need replacing. I don't see a ton of wear on the teeth of most gears, but I was unable to get the main shaft assembly apart because everything is so rusted together. I hit it with a ton of WD40 yesterday and let it sit to see if that will loosen things up. My plan is to do that again this weekend and take a brass bristled brush to everything to see if I can remove the rust and start getting things apart. I will take a few more pics of everything and post them so you all can see what can shape everything is in.

Thanks for all the replies! I appreciate you all sharing your wisdom with me!
-Alex

If you need any more "eyes" shoot some pictures of the questionable parts. We might be able to help with a decision. Be sure to review the correction below to Rick's guide. It will definitely make that part easier. You can damage the reverse idler shaft and/or the case by driving the idler shaft from the inside, out of the case. I have found the Universal Jeep Service Manual does a very good job of walking you through the rebuild.

https://willysjeepforum.kaiserwillys...-Stivers-Guide

I just saw that on another thread. Luckily, I did it correctly yesterday. It seemed much easier to drive the shaft into the case, so I did it that way. I will definitely shoot some pictures of the components and see what you guys think.

Good thing you caught that. You can do some damage driving it out the other way. Looking forward to the pictures. Focus on the bearing surfaces. Those need to be perfect if you want it to last.

Hey guys, it's been awhile but I've finally found time to get the transmission apart and clean so I could share some pictures. Again, I'm wondering how to proceed given the condition of the parts. I'm willing to put the work in to restore parts if possible, but I would rather not put parts that should be replaced back in and end up doing all of this again in a couple years. The gears and shafts look to be in kind of rough shape. There's a significant amount of rust on a lot of the teeth and on the shafts. I got quite a bit off with a wire brush, but there is definitely still quite a bit. There is also some pitting in a few places that I'm not crazy about. I would love everyone's opinion on what parts should be replaced and what can be reused. Attachment 9837Attachment 9838Attachment 9839

Apparently, I can't post more pics on the forum for some unknown reason. Any advice on how to share these?

Alove,

I'm the first guy to insist on using as much of the original parts that you can during a restoration. With that being said, if it were me working on your transmission, I would use new shafts and gears. This route will prevent you from having issues down the road, and creating rework for yourself. The gears have been worn, and the shafts are pitted. Save yourself the head ache, and replace the internals. The original parts would work, but issues would arise in hanging shifts, or premature wear in the gear sets.

gm has you on the right track. Any surface that bearings will be running on, will not tolerate pitted surfaces for long. Your bearing surfaces need to look good with no damage. Under the bushings you can get away with a little more pitting but not wear. No wear (oversize) is allowed on the bushing or bearing surfaces. On the gear teeth themselves rust damage if it has gone thorough the case hardening of the tooth, will cause issues. Pitted rough gears are noisier. If the clutching teeth on the gears are worn, shifting and staying in gear will become a problem. If the bushings or the main shaft are worn, shifting will again be affected. Discoloration is not a problem. Some wear is OK. Your reverse/first slider needs a better look. Lets see some more pictures of it. Rust has a way of just ruining a transmission. Unfortunately on the T90 in a Jeep, a lot of them sit out in the weather. If the boot is torn or leaking in the least bit on the shifter, water runs right into the transmission. Even if it is protected, if has been sitting a long time condensation will do its worst. This is why there is a "time" specification on lubrication changes, gotta get the water out.

The best advice here would be "when in doubt, throw it out". It is truly a "pay me now or pay me later" situation. If you are looking to get it moving, I have seen some pretty bad stuff go back to together, and kind of work. There is of course a correct way that will return it to it's original function and performance.

You can add more pictures. You can only add so many to each post however. Just add a few posts in a row.

Thanks for the advice/information. It basically confirms what I was already thinking. I tried to fit everything back together after cleaning it and the gears really don't want to move along the shaft with the pitting and some of the surface rust still there. I'm looking at the overhaul kits at Kaiser Willys currently, and I think I will probably just bite the bullet and pay for all the new internals and a new shifter since mine is in rough shape and has definitely seen better days. My case is in pretty good shape. I'm planning to have a friend sand blast it for me to get the rust out of the inside. I worked on it with a wire brush but some of the angles are tough to get at. Is there anywhere else that I should consider looking for an overhaul kit? I've been super impressed with the service at Kaiser Willys but things are a little pricier there sometimes.

Thanks,
Alex

There are a few gear vendors out there. The extra at KW goes into the no questions asked returns. You really don't have to worry about what you buy from them. No matter what, they will take it back.

If you can find it NOS stuff is the way to go. There is a lot of cheap stuff out there. If you can find USA made that is the way to go.