Transmission issue

[jikemire]

I bought a '49 MC from a great guy in eastern Kentucky. Runs like a sewing machine! He put new steering clutches on both sides and several other things. Just a great little machine for what I'm working on....nothing big. Seldom pushing more than half a blade full of dirt. When you release the clutch in neutral there is a growling sound from the transmission...can kind of hear it when using in gear. Yesterday it began chattering in all gears and would stop driving. At that point I would change gears or into reverse. It would start to pull itself but then stop and I would hear the chattering again. The chattering sound is both loud and "solid" sounding. Definitely coming from my feet area. Reminds me of trying to put something in gear without using the clutch...grinding noise. What am I needing to look for? Thanks in advance.

[fundytides]

I would pull the transmission cover and see if there is anything obvious. If not, I would suspect the propeller shaft that runs from the clutch to the transmission. The internal spline on this shaft where it connects to the transmission was worn down to almost a knife edge when I pulled mine apart. It was still working ok but probably would have failed soon and I suspect would have displayed the symptoms you are describing. The other possibility is that your clutch disk or pressure plate has failed. You might be able the try the machine in gear with the trans cover off to see if the transmission stops turning when the noise starts. If it does, you will have to pull the motor to look at the 2 possibilities that I have described. Others with more experience may have other ideas. In any case a JD service manual and parts book are invaluable. Good luck and let us know how you make out.

[jikemire]

Thank you. I left it in the woods and am gathering tools now to go out and take a peek. Say the issue turns out to be in the trans...the book I have shows I should be able to pull those internals out the rear. I'm hoping it's that easy...but it's me.

[Lavoy]

There is no transmission work that can be done with the trans in the crawler. It will need to be entirely removed from the crawler, and then you can start tear down.
Lavoy

[jikemire]

Alrighty...took the cover off and all looked great. Slid 1st gear into place and it will start to turn the whole set but stops when the chattering starts. I'm guessing the splines as you described fundy. The reason I say that is the guy I bought it from had it all apart and stated the clutch was good. I know the springs in the pressure plate can get weak but my experience with old farm tractors is I've had a clutches go out and they never acted like this. I haven't got it home yet and when I do it will be next week before I can dig into it. If I do need the shsaft I'll reach out to you Lavoy. Thanks guys!!!

[fundytides]

Yeah, a weak pressure plate would not cause what you described. It would have to something more catastrophic like the hub breaking out of the clutch disc or ? I would pull the motor and then if you don't see anything in the clutch area try to turn the propeller shaft with the trans in gear. If you can do that, follow the directions in the manual to remove the propeller shaft.

[Lavoy]

Just a thought, stripped prop shaft!?!?!?!? Real common on MC, 40, Phase 1 420.
Lavoy

[jikemire]

From everything you guys have said I'm betting that's what the problem is. Replacements hard to find? Anyone make new ones?

[fundytides]

I was lucky to have a good used one from a bunch of parts I bought from a guy one time so I didn't have to look any further. Lavoy may be able to help or maybe a good machinist could fix the old one.

[Lavoy]

I can rebuild them.
Lavoy

[jikemire]

Finally got it home and in the garage. Took the gearshift cover off and drained the gear oil. At the bottom I found 14 rollers from a bearing but no bearing cage remnants. Bearings were ground up a bit but no broken pieces. I suspect one of the two bearings towards the rear of the input shaft.

As I slid the trans back I noticed there was nothing holding the propeller shaft to the input shaft. Although I did find a small bolt with a nylon stop nut on it, remnants of a rivet and a screw laying at the bottom of that portion under the clutch shaft. I'm assuming someone prior did not want to bother with the groove pin the book calls for. I'm wondering is that pin to keep endplay in check? If so, could the propeller shaft move towards the front of the crawler enough to cause it to not engage? The end of the input shaft looks great and the inside of the prop shaft feels clean with good edges.

Any thoughts/ideas would be greatly appreciated.

Thanks,
Jerry

[Lavoy]

You are looking at a total tear down of the trans, do not run it at all, not even idling stationary. Those are bearings from inside the cluster gear I would guess.
Lavoy

[jikemire]

Lavoy,

I was figuring so. Might as well replace all the bearings since it's apart.Any comment on the propeller shaft?

Thanks
Jerry

[Lavoy]

Prop shaft coupling is most likely worn, I can rebuild that part. If the trans splines are worn, probably need to look for a different input shaft.
I stock the prop shaft retaining pin and washer.
Lavoy

[jikemire]

Today I found the squealing noise I described in the original post in this thread. In the left side as seated, the repair manual refers to it as a "quill". The bearing there was completely destroyed. A chunk of the quill was broken off and even about a half inch of the race was missing! Does anyone have one laying around they'd be willing to sell? I don't weld cast very well. TIA

Jerry