Transmission, Transfer-case, Clutch

July 1-4, 2000

Background | Removal | T-case | Clutch | Tranny | Tools | Cost | Postscript

Background

I have had on-going noise from somewhere in the drive-train , especially during engine braking. The previous owner told me when I bought it that it was the pilot bushing. Until recently I have just lived with it, but it has always bothered me and made me wonder if I was in for a major breakdown on the trail someday.

Since the jeep had been sitting for over a year, I changed all the fluids before the maiden trip with the new carb. The oil from the transmission had chunks of metal in it. A few days after the run there was a pool of gear oil under the jeep. Upon closer inspection, it seemed to be coming from the t-case yoke seals.

If I have to pull the transfer case to check on it, I might as well do all the work I can on the other driveline parts. I plan to rebuild both the tranny and t-case and to install a new Centerforce clutch. I also need to replace a lot of the parts in the clutch linkage, so I will do that at the same time.

Removal

I spent half a day removing the transmission, t-case, and clutch. The process took a lot longer than I expected. I ran into several problems along the way. I started by putting the whole rig up on jack stands. This made it much more stable and a lot safer than trying to block the tires. It also provided quite a bit more room to work under the truck.

All of the instructions I had said to remove the trans, t-case and crossmember as a unit, but there was no way to properly support it all with the tranny jack adapter I had for my floor jack. I put a jack stand under the bell housing and removed the crossmember. One of the bolts was stripped, so I ended up cutting it off.

Once the crossmember was out of the way, I connected the jack to the tranny and raised it slightly. I then disconnected the speedo cable, vent tubes, shift levers, boots and access plates. I then unbolted the transmission from the bell housing, and lowered the whole assembly a couple of inches. I needed to move it all toward the back of the truck several inches to get the pilot shaft out of the clutch unit. Because of the way the jack rolls, this was rather difficult, but enough pushing and pulling got it free. I then lowered it all the way down and tried to pull it out from under the jeep. It was still too tall to come out easily. I had to tilt it back and forth to get it past the frame rails.

Transfer Case

The first chore was to clean the case up enough that I could work on it without contaminating all the gears. I spent a couple hours scraping grease and dirt off of it then used a drill with a wire brush to clean it up more. At this point I removed it from the transmission and put it up on my workbench.

I followed the instructions from the factory service manual, and disassembly was pretty straight forward. Once I had it all apart, I cleaned it some more and put all of the gears and metal small parts through a can of parts cleaner. It worked great and the insides looked like new. The gears and bearings were in great shape and probably did not need to be replaced, but since I had a full rebuild kit I replaced the bearings anyway. It was good practice and I didn't want to have to do it again for a long time. The oil seals were in bad shape, so I didn't bother trying to save them. This made disassembly much easier.

For the rebuild I used the new parts whereever possible (bearings, seals, washers) and again followed the instructions. The only difficult part was holding the poppet balls in place while inserting the shift rails. I think it flew out a dozen times before I got it to work. Once it went into the garbage can and I spent the next 15 minutes digging through garbage to find it. Using petroleum jelly to hold the roller bearings works really well and made it much easier than I would have thought possible.

It is now done, clean and ready to re-install.

Clutch

I first removed the starter. It's gear looked quite worn, so I will probably rebuild or replace it. Next I started to remove the bell housing and quickly realized something was seriously wrong when it started moving a lot before I loosened anything. It turned out that half the blots were missing and the other half were loose! I'm surprised that the whole drive train hadn't fallen out the bottom of the jeep long ago. The clutch linkages and forks were shot too, but I already knew that, so I had ordered new ones for the rebuild.

With the bell housing out of the way, I was able to remove the cluth plate and disc. The disk was badly scored and burnt. Good thing I had a new Centerforce clutch to put in. The flywheel was also varnished, so I removed it to have it resurfaced. I had already planned on doing this since it is recommended whenever you replace the clutch disc. I also discovered that the pilot bushing was missing. Argh!

Once the flywheel was done, installation of the new clutch was a breeze. Make sure you have a clutch alignment tool. Most of the places I tried to get one claimed there was a special one for jeeps with a 258. I finally gave up and got one that looked right and it worked fine. Just make sure it is 10 spline and 1 1/16".

Installing the bell-housing was pretty simple once I had all the right size bolts. Since several were missing it took a little time to determine the right sizes and quantities. I then replaced the linkage with new parts.

Transmission

Disassembly was pretty straight-forward here as well. Removing the lock rings was a bit of a pain. Once I realized that there were new ones in the rebuild kit, I just bent and pried until they came off. I'm sure there is a tool to make it easier, but I eventually got them off. Removing the intermediate shaft and reverse idler shaft was also a bit rough. They can only come out the rear, but I didn't realize this until I had them quite wedged. I ended up building a tool like an inside-out gear puller to push the shafts out. Be sure to wrap the syncho assemblies in a cloth before sliding them apart. If you don't, the poppet balls will become projectiles and either hurt someone or get lost. Of course this didn't happen to me. ;-)

Once it was all apart, I cleaned the inside well and put all the gears and small parts through the parts washer. The larger gears would not fit in the washer can, so I just wiped them down well and sprayed them with WD-40.

Reassembly started with the intermediate gear and the reverse idler. Again, the petroleum jelly trick helped alot. With 88 roller bearings in the intermediate gear and 54? in the reverse gear, it would not have been fun to do it any other way. Both assemblies went in place easily.

Next came the main shaft. Building the synchro assemblies brings those d*mn poppet balls into play again. Buy some spares, you will need them! I shot steel balls all over before I finally got it done.

Puting all three shafts back in the case was pretty easy. I did manage to get the main-shaft bearings swapped and that caused problems until I figured it out. They are both the same diameter, but one is wider than the other and would not seat properly.

I temporarily put the shift housing back on to verify that it shifted correctly. I then mated the t-case and tranny together to test test them. It was quickly obvious that something was wrong. The output gear from the tranny stuck too far into the t-case and got bound up on the t-case output shaft. After taking apart the output section of both parts, I finally realized the source of the problem. The rebuild kits did not come with gaskets for either side of the tranny/t-case adapter, so I had used RTV. It did not provide enough spacing to pull the output gear back where it belonged. I got some gasket material and made my own and it worked perfectly.

The two parts are now mated and working smoothly together. Now I need to find a strong person to help me get them off the work bench and onto the floor jack.

Once on the jack, installation was not too bad. Getting it aligned took a bit of work. You don't get much precision when moving something that heavy. I had it most of the way in when I realized that one of the mounting bolts has to be installed from inside the bell housing. Doh! Out comes the tranny and off comes the clutch fork so I can get the bolt in.

With a little work, it all goes back in place and the holes actually line up pretty well. After it was all bolted up, I put the drive shafts back on and hooked up all the breather lines. I then started it up and tested it. I need to adjust the cluth a little, but one that was done, it all seemed smooth, but it was still up on jacks. I filled it all with gear oil and put the interior back together in preparation for a road test.

I did a little slow testing in the driveway and it seemed OK. I then took it out on the street. As soon as I tried to shift into 3rd, it ground but went in. Fourth was the same. After a few more tries, I came to the conclusion that something was wrong with the 3rd/4th synchros. 2nd shifted smoothly, so it seems to be OK. I took it back home and put it up on jacks to check it out some more. The problem still seemed the same, so I left it up and tried to decide how to proceed.

A couple of weeks later I got the time and the motivation to pull it out and see what I could find. Since all the bolts were fresh and I knew what I was doing, it was much easier this time. I also learned from last time and pulled the exhaust off the headers to get it out of the way.

I put the tranny on the bench and opened the top. I first focused on the synchros themselves since they seemed loose when I installed them. After playing with them for a while, I finally figured out how they were supposed to work and realized that they were the wrong parts. I pulled the main shaft out and removed them. I compared them to the original parts and sure enough they were not the same. The shop I bought the rebuild kit from insisted that the T18 and T19 use the same kit. I didn't think that was right, but they were the experts, so I took it. Now I know that is not correct. The basic rebuild kit probably is interchangeable, but not the synchros. I put the original ones back in since they really were not in bad shape. Once I had it back together on the bench, I played with it a bit more and it seemed to be working properly this time.

I put the tranny on the jack and then attached the t-case so I did not need help lifting it this time. It went back in pretty smoothly and I got it all hooked up. Before puting the cross-member and exhaust back on, I tested it while still on the jack stands and it seem to work correctly. Man, the engine sounds like a monster V-8 without the cat and muffler. ;-) Maybe I will replace them with something more freeflow someday.

BTW: The height of the t-case changes the distance from the firewall to the carb. This means that the throttle cable(s) needs to be adjusted. When I started it up with the t-case on the jack stand, I didn't realize this and the engine "idled" at about 3000 RPM. Oops.

I put the remaning supports and exhaust back and road tested it. Now it shifts smoothly into 2, 3 and 4.

Special Tools Required

Most of this project required only basic hand tools. There were a few tools required that might not be in every garage, so I list them below for anyone that is looking at doing this themselves:

• Floor Jack with transmission attachment
• Clutch Alignment tool
• Some kind of tool for removal/installation of lock rings

Cost

Postscript