Inspecting T86 And Transfer Case

hello everybody,

While I’m waiting on a new clutch kit and clutch release fork and before I start fabbing up new motor mounts I would like to give the t86 and transfer case a good look over.

What’s the best approach to this. It goes through the gears on the bench, but I have never driven it. And the transfer case appears to work as it should from rolling it around. Any thoughts would be great.

Mike

 

I found these videos very helpful. T14, T86, T90...all very similar.

 

Great Videos! So i can pull the top plate off the transmission which will take the shifters and forks with it, so I can inspect the gears inside? I have a feeling the transmission is ok, but not so much with the transfer case. I saw some water come out of it, so Im a little worried about it.

 

Yessir, top and shift forks lifts right off. On the D18, taking the bottom pan off will give you a good look inside. Many of these Jeeps that get parked outside get water in the transmission and transfer case. If the rubber shift boot isn't 100%, rain water runs down the shift cane and seeps into the transmission and ultimately the t-case since they share oil.

Some water is not always dire though, just have to open it up and take a look.

Gasket and Seal kits are fairly cheap...for the D18 anyway. Not sure about the T86, kind of a rare bird only produced for 2 years or so.

Post up some pics once you get in there. Folks here will be able to give good advice.

 

Drained the sludge out of it and some water. There wasn't much oil in there. Opened up the top plate and this is the inside.

I sprayed it down with some pb blaster to loosen everything up a little, and breakdown some of the sludge in there. The 1 and reverse gear moves freely, not so much for the 2-3 syncro. Also the case says t86aa, but are the internals from a t90....Im new to these trannies and early jeeps so still trying to navigate my way around.

 

The internals are T90. That much rust will cause issues for a transmission that get mile put on it. If you are only going to keep the Jeep very local, you can probably get by cleaning up what you have.
Water in the transmission doesn't hurt much if you catch it right away and change fluids. If water stays in the trans/TC for a while, it pits the gears, shafts, and bearings.
-Donny

 

Thats what I thought about the internals...Ive rebuilt the automatic for my race truck a few times, I may do this one as well. The gears all look in good shape as far as the actual teeth, but have some surface rust on them. They would all probably clean up nice...Im more concerned with the needle bearings with the water.

 

So after looking at everything and watching some videos online by Rick Stivers Ive decided to rebuild both the trans and transfer case. They are already out, and on a bench, its almost stupid not to. Easier now than later. Ordered both kits to rebuild each of them, so hopefully I can have them done in a couple of weeks.

 

Typically you'd replace the t-86 input and output bearings, all the small parts, the blocking rings, and look at the fit of second gear on the main shaft. If worn, it will skew and push the shift collar away from second gear. This results in coming out of second when decellerating. Does the T-86 have a neoprene input shaft seal? I think it's like the T-90, with a felt seal and a drain back to the case. The T-90s sometimes leak out the input shaft. There is a sealed bearing conversion for the T-90; it should work for the T-86 too.

What does your video say about a premium intermediate shaft for the D18? The hardened Novak shaft is popular, and Herm has a premium shaft too.

 

Interestingly enough my case is stamped t86aa but has t90 guts, so I’m assuming it has a t90 seal. I have seen the sealed bearing setup and will probably end up doing it.

I haven’t investigated the d18 too much yet, but have heard about the Novak shaft. This Jeep will not be seeing any real “hard” off-roading so I’m not too worried about upgrading to the hardened shaft. Maybe the occasional trip onto the beach that’s it.

As I get everything all apart I’ll start posting more pics.

 

Upgrade to the hardened shaft! That is what the D18 had when new and it is the only way to go, other than machining for taper rollers. The other shafts are aftermarket soft garbage that will wear grooves from the needle bearings in a few thousand miles, if not sooner.
-Donny

 

Rebuilt the t90 last night. I noticed a couple of interesting things, the front bearing is held in by the adapter plate that mates it to my ford 302, and rear locking plate is either ground or recessed so that it does not hold the bearing retainer/ plate in, and it seems that the transfer case will hold all of that together. Also I don't have a oil collector....I don't know what the ramifications of this is but its not there. Otherwise everything seems so much smoother than before. Overall not too bad to do. As soon as my transfer case kit comes I will be tacking that.

 

Treated with phosphoric acid, primed with duplicolor engine paint and painted with duplicolor semi gloss black engine paint....just a lil better looking.

 

I believe the oil collector (the trough that bolts in) was only used on the earlier T90A model. The T90C did away with the oil collector.
-Donny

 

Great thread @Stano316 . Can I ask you a favor next time you are in your garage? Can you see if your control tower is stamped "T86?" Here's mine:
I have a T86AA-1B case, but the control tower says T90C-148D. Are these a mis-match by the PO? Did the T86 have a matched tower when it came from the factory? What's different about the two?

Also - I was sad to see that Bubba over-tightened the tower bolts at some point, and snapped off two of the threaded bolt holes in the top of the case:
All of the gears look like they are in great shape, everything moves well, there's clean newish oil in the case, no sign of pieces in the bottom at least with a magnet, and I'm trying to convince myself that I don't need to tear it apart just to fix these holes, which since the case is Cast isn't even something I know how to do. But then again , it's on my workbench, so it's now or never. Love to hear the experts' thoughts on whether these broken holes are a big deal.

 

If it was me I would just find another case . and yes it could be welded with ni-rod (expensive) . but that requires area of repair must be preheated with a oxygen/acetylene torch . after welding it must be placed in sand or wrapped in a heat blanket . to allow to cool slowly . I have found ni-rod works better a AC setting on welder

 

Those are definitely T-90 gears in a T-86 case. This is the usual way you repair a T-86 with broken gears. However, you need to replace all the gears - all T-90 or all T-86 gears, nothing in between. I recall you need the T-90 forks too, but I thought you needed to take the shift top apart and swap them. Someone here may know for sure, or Herm would know. Your PO may have tried to force the T-90 top onto the T-86 case, which may or may not fit - IDK.

 

Yeah, my control tower was also stamped t-90, and case t-86, all my internals were from a t90. Unfortunately my jeep in on hold for a few months, we unexpectedly sold our house in a day, and will be moving in a month or so. So I had to put the body back on to save space in my garage. On a better note, I will be getting a bigger garage to play in, so I don't mind the hold on the project.

 

The "hold" will give you time to search for, and round up parts!