Ford 1710 final drive problem

MMMTreeman · Apr 30, 2018

My 1986 Ford 1710 has been having an intermittent problem in its' final drive. From time to time, the left wheel locks-up. Generally, it will reverse with no problem, but it will only go forward just shy of a complete revolution before it locks-up.
Usually, reversing for some distance, like the 1/2 mile it takes to get home, will eliminate the problem. Until the next time. Which might be months or years. This has happened on flat ground, but more commonly it happens when I'm working on a slope with the left side on the downhill.
This has been going on for years, but recently has gotten to the intolerable stage.

So...this is where I am now. The tractor is in the garage and our nice new car is out in the weather. I removed the top of the differential/pto case and flushed everything with diesel from a garden sprayer and compressed air. So far, I have retrieved 4, 13mm bolt heads, sheared-off clean, 2 6?mm bolts plus a sheet metal bolt-head keeper with one end clipped off and the other part entire, plus another keeper ground to bits and a couple ounces of misc. ground-up metal bits. The mystery is where did all this come from? There is no indication of anything missing or broken anywhere that I can see, so far. And all the bolts inside the case are larger diameter.

Sounds ominous doesn't it? Then why has my tractor been functioning flawlessly (excepting the current problem) for 2400 hours over the last 19 years?
This is actually the second tear-down over the last 3 weeks. During the first go-round, the right wheel locked-up same as the left and I retrieved a headless bolt wedged in the teeth of the final drive gear and that solved the problem. I tried to re-create the problem in the left wheel and couldn't.
So I buttoned it up for a trial run, which ended at the shop door with the left wheel locked-up again.
At this point I am getting a bore scope camera programmed for a closer look where I can't see otherwise. But if that fails I'm looking at removing the entire left final drive to ,as the old song goes. "...see what made it so."
Thoughts, suggestions, similar experiences?
Thanks,
Martin

Kernopelli · Apr 30, 2018

Sounds like the ring gear bolts have sheared off. Parts diagrams are available at New Holland Parts | Buy Online & Save

MMMTreeman · May 1, 2018

Darryl,
Thanks for your thoughts. My IT shop manual has adequate blow-up drawings. ewxcept the two drawings on the relevant page are cross-labeled which led to some confusion.
No, my ring gear bolts are intact. In fact, everything I can see in the differential/pto case looks fine. That's why all this metal junk is such a mystery.
The ring gear and pinion appear to have been changed B4 I bought it at 800 hours. So our current thinking is that these bolts got left behind by another shade-tree mechanic. But the only bolts this size aare thew bolts on the brake cover, and all those bolts have lock washers, not sheet-metal keepers. So it's still a mystery.
Martin

MMMTreeman · May 1, 2018

Darryl,
OK, thanks for the link to NH parts. Being able to blow-up the diagram is a big help. and parts availaability is good too.
Martin

Kernopelli · May 1, 2018

MMMTreeman;5076890 So our current thinking is that these bolts got left behind by another shade-tree mechanic. But the only bolts this size aare thew bolts on the brake cover said:
Sounds very plausible. It is AMAZING that it didn't cause additional damage, especially after years of symptoms! Waiting patiently to hear how this turns out!

MMMTreeman · May 1, 2018

Kernopelli said:
Sounds very plausible. It is AMAZING that it didn't cause additional damage, especially after years of symptoms! Waiting patiently to hear how this turns out!

Darryl,
You couldn't be more amazed than I am. Seems like all that junk just settled-down into the final drive drain sumps and sat there. It only made trouble when the final drive gear picked-up a bolt and jammed it into the pinion gear.
The left side pinion gear does have a minor hesitation once per rotation. So I'm betting I find a dinged-up tooth there when I get brave and pull-off the whole final drive assembly. If that's the worst of it, I'll count myself lucky.
My brilliant brother just suggested that I handle this heavy stuff with my engine hoist instead of the come-along hanging from the garage roof trusses.
DUH...Sometimes I just get tunnel vision.
Martin

MMMTreeman · May 7, 2018

MMMTreeman said:
Darryl,
You couldn't be more amazed than I am. Seems like all that junk just settled-down into the final drive drain sumps and sat there. It only made trouble when the final drive gear picked-up a bolt and jammed it into the pinion gear.
The left side pinion gear does have a minor hesitation once per rotation. So I'm betting I find a dinged-up tooth there when I get brave and pull-off the whole final drive assembly. If that's the worst of it, I'll count myself lucky.
My brilliant brother just suggested that I handle this heavy stuff with my engine hoist instead of the come-along hanging from the garage roof trusses.
DUH...Sometimes I just get tunnel vision.
Martin

This is how it turns out: I pulled the final drive and this is what I found: YET another bolt head, mashed. This makes 5 now. (The sheet metal keepers are 2-holers, so there should be 6 bolts/heads? Ground to bits, I guess.); the pinion shaft gear (11 teeth) has 6 teeth damaged. (2 with big chunks missing, 4 tweaked some more, some less); the reduction "bull" gear (70 teeth) has 1 tooth mostly missing and the other 6 are tweaked.
So, it is all disassembled with no more drama and used parts are ordered. all the bearings and seals look fine
.
While I had better access, I probed the transmission case bottom with the magnet probe and drained the 4WD driveshaft sump looking for more junk and didn't find any. So where the junk bolts came from is still a mystery.

Kernopelli · May 8, 2018

Well, it stinks that it turned out there was additional damage. Sounds like it will soon be as good as new again. Keep us updated and you know we love pics!

MMMTreeman · May 17, 2018

Kernopelli said:
Well, it stinks that it turned out there was additional damage. Sounds like it will soon be as good as new again. Keep us updated and you know we love pics!

Darryl,
The tractor is finally out of the garage and everything seems to be nominal. When the used parts arrived, I was pleasantly surprised to find that the pinion shaft came with both bearings and the oil seal in good shape. So I just installed it all together. Now I have spare bearings and an oil seal that I hope I NEVER have any use for!
Thanks for your interest and help,
Martin