T15 Noise & Rebuild (?)

Hi all,

I have a '74 CJ5 w/a 304/T15/D20 combo. It sat for the better part of 20 years before I acquired it. After getting it running, I noticed a sound at idle, in neutral, with the clutch out. Conventional wisdom seems to suggest that it's an input shaft bearing issue and that's exactly what it sounded like. My first thought (or maybe hope) was throwout bearing, but they typically make noise with the clutch pedal depressed and the throwout bearing under load.

I pulled the trans this past weekend and put it on the bench. It looks great. No noise or strange feeling when rotating the input shaft. I would think if it was bad enough to make noise that I can hear in the driver seat, I would feel it when rotating by hand. The trans shifts fine and I don't see any issues from a visual inspection from the top.

The throwout bearing, on the other hand, is shot. It makes all kinds of noise and feels chunky when I spin it by hand.

I figure that if the trans is already on the bench, I should at least pull the input shaft and inspect the bearing more closely. I have read that for some of these transmissions one can wiggle the input shaft and bearing out as one unit. Can anyone confirm if that is possible with the T15? If not, I'll need to source a bearing puller/separator.

I am firmly in the "if it ain't broke, don't fix it" camp, but I'm also pretty solidly in the "it makes good sense to do it while the part is accessible" camp. I'm tempted to just go ahead and rebuild the trans. It would be nice to learn a little something while I'm at it.

Thanks in advance for any thoughts/input!

 

I vote for buy small parts kit/gaskets and seals and go thru it. Peace of mind when done and that is a very simple trans to work on. Be sure to drop the countershaft and pull cluster gear for inspection. mike

 

I would replace the front main bearing regardless. In my experience, you cannot feel the roughness in the bearing unless you remove the bearing from the transmission and input shaft. You need to wash the oil out, feel it turn, and look at the race under bright sunlight or other intense light.

The T-18 in my J20 uses the same input bearing, and I had the same issue. It looked and felt fine when I had the transmission on the bench. The problem became clear once I washed the bearing and could look closely at it in full sun, and felt it turn.

I've only had one T-15 apart, and I was able to remove the input shaft and the bearing together. IMO that does not help you much, since you should replace the bearing regardless. Maybe you can press it off the shaft. I made a puller for about $60, in this thread: T-18 in the driveway - Full Size Jeep Network You should read my experience sourcing this bearing, also in this thread.

The other possibility is the pocket bearing in the end of the input shaft. The main bearing is more likely, but you need to take the input shaft out and inspect both.

 

Just to affirm what Tim said. I recently did the T-14 in my ren 2 and after reinstalling had a noisey bearing.
Always fun doing that job twice.Ended up the input bearing was not perfect and made a noticeable growling sound.All is good now. Can't be to careful. mike

 

Thanks guys. I was able to remove the input shaft and bearing after driving the countershaft out so that those gears could drop out of the way. I think that I can press the bearing off now. That said, I'm this far in, so I'm going to obtain a puller to get the rear bearing out and look it all over carefully. I'm curious if availability of quality bearings has changed since 2016. I'll poke around and see what I can find.

 

Sometimes a guy just has to think on a problem for a while. I’m not the smartest guy in the world, but I am slightly smarter than a couple of 45 year old bearings. Turns out the fit isn’t all that tight. I was able to put the big outer snap ring on the output bearing and convince it to move with a couple of pry bars. Once it moved a little, I could get a conventional two arm puller on it. I was able to press the input bearing off. OK fine... I don’t have a press. I told my big hammer that it was a press and it’s too stupid to know any better.

 

The only T15 I've ever owned, the pocket bearing went out and destroyed the input shaft AND the mainshaft! $$$$$$$
Take a close look at those little rollers while its apart.

 

As I recall, there is a crescent cut-out in the 3rd gear synchronizer teeth on the input shaft. If you align this with the cluster shaft gear, you can remove the input shaft without dropping the cluster gear.

 

Not with this T-15. I had hoped that was the case but apparently you can with some gear combos and cannot with others. I spent a lot of time trying to line it up with no success. As soon as I dropped the countershaft, it came out very easily.

I'm glad that I took it all the way apart. When I pulled the top cover off, I set it aside without looking at it. I pulled all of the guts out of the case this evening and found a big hunk of cast iron at the bottom. Uh-oh. Fearing that I broke something during disassembly, I spent 10 minutes trying to figure out where that piece came from. It finally occurred to me to go look at the top cover. A chunk is broken out of the housing holding the 2nd/3rd shift rail in place. It's broken in such a way that the shift rail hasn't moved - likely held in place by the shift fork. In any case, I'll need a new top cover. I can't find any other damage. I'm wondering now if that is the source of the noise I was hearing.

It was last driven by a teenager before sitting for 20 years. hard to imagine how it would fail in this way, but I remember all the stuff I broke as a kid.



Using zip ties to keep everything in order until new parts arrive.

 

They look great. All eleventy billion of them!

 

Not the same transmission but I found this video (and part 2) very helpful in making sense of the process.

 

could the pilot bushing in the end of the crank cause that . its already apart anyways.

 

Seems possible - I can’t really rule anything out. I’ll check it out next time I’m in the garage. It’ll get a new pilot bushing while it’s apart.