Yanmar YM1510D – Front Wheel Assist Not Working

[ponytug]

Thanks for the insight. I progressed through your suggestions then found these gears on both left and right with some teeth missing. In a quick search this seems to be one of the hard parts to find, correct? Part #194441‑13950 I believe it is called the front‑final drive bevel gear. I reached out to lens12 as I saw he may have had some machined at one point. Any other ideas how to locate two of these?

That's a very odd failure pattern. Have you found a chunk of metal there? Or at least filings? Were the front axles grossly loose?

If you can't find replacements, I'd take it to a machine shop to see if they can fill in the holes. In the reassembly, if it were me, I would make sure that I had the gears shimmed correctly to mate properly.

All the best,

Peter

 

[California]

Unfortunately that gear is only used on the YM1510D.

Does the US twin, the YM186D, use the same gears? Now you have me spooked if those bevel gars are irreplaceable.

Running entirely on soft and sloping orchard ground, I almost never shift out of 4x4 - only when I (rarely) go out onto the hardpacked lane.

 

[YanmarMatt]

That's a very odd failure pattern. Have you found a chunk of metal there? Or at least filings? Were the front axles grossly loose?

If you can't find replacements, I'd take it to a machine shop to see if they can fill in the holes. In the reassembly, if it were me, I would make sure that I had the gears shimmed correctly to mate properly.

All the best,

Peter

There were some filings and chunks. I’m trying to find a machine shop that may be able to weld it up, then machine it down.

When I would spin the left wheel I could spin it almost an entire revolution before the right wheel would engage. Whereas the same test on rear wheels engages immediately. If that’s what you mean by loose then yes they were loose!

If anyone has a good machine shop I’m happy to ship the parts. It’s not time critical that this gets fixed. I’m in AZ so it’s still 110 degrees. I’ve got a few months until tractor season.

 

[YanmarMatt]

Does the US twin, the YM186D, use the same gears? Now you have me spooked if those bevel gars are irreplaceable.

Running entirely on soft and sloping orchard ground, I almost never shift out of 4x4 - only when I (rarely) go out onto the hardpacked lane.

My 4 wheel drive engage lever broke so I typically always keep it in 4 wheel drive, but I may need to fix the lever to take it out when not needed. Most of my work is on dirt, but it broke when I was moving rock for a friend.

 

[ponytug]

There are a fair few machinists here, but I would look locally first.

I'm having trouble visualizing what could cause one to be able to spin a wheel 360 degrees before the other wheel began to turn.

All the best,

Peter

 

[winston1]

For what it is worth I agree with Aarons suggestion.

 

[AaronM]

Does the US twin, the YM186D, use the same gears? Now you have me spooked if those bevel gars are irreplaceable.

Running entirely on soft and sloping orchard ground, I almost never shift out of 4x4 - only when I (rarely) go out onto the hardpacked lane.

Surprisingly the 186D uses a completely different 4wd axle design. I don't think they share a single part.

Aaron

 

[California]

Surprisingly the 186D uses a completely different 4wd axle design. I don't think they share a single part.

Aaron

Thanks Aaron. I had read that the US YM186D has a heavier front axle to make it suitable for loader use. This is the first time I've seen confirmation that they are different.

 

[Oz_Kioti]

This won't help the OP, except maybe for the fact that my problem was down to the operator - me!

Tractor was LG47hp (LG now LS) and I abused the front axle by asking the FEL to do what it wasn't designed to do, placing horrendous down loads on the front axle, and REALLY subjecting the forks on the FEL to horrendous shocks to try to jerk out tree stumps which demanded something beefier than a 47hp tractor!

Covid BS had just hit at the time, and getting parts out of Korea was just not going to happen. Dr Google located two new bevel gears from a dealership in Missouri which a friend shipped over to me, and from my searching, they were the only two new ones in existence. Maybe the factory might have been able to assist, but the Australian importer couldn't even get LS to talk to him at the time!

They were in a bad way:

 

[YanmarMatt]

Update:

Thanks again, everyone, for all your help so far. It’s been reassuring to know that I can ask questions here and get such thoughtful advice.

I was working on my tractor again today and wanted to share what I’ve found:

• I removed the left axle cover to check for stripped gears—so far, nothing looks destroyed in there.
• I pulled the driveshaft, and the lower U-joint looks a bit scuffed up. It’s not completely broken, but I think I’ll go ahead and replace it.
• One thing I’m still debating: On the front differential, where the driveshaft connects—if I spin that input gear, I would expect the axle spindles to turn. However, they’re not.
• Looking behind the left plate, I can see a gear spinning, so something is moving internally.

My main question now: Is there some sort of clutch or mechanism in the front differential that engages the wheels? If so, I’d like to understand how it’s supposed to work so I can troubleshoot more effectively.

So far, I’m encouraged not to have found any completely destroyed gears—just the chipped

gear I posted about earlier and the U-joint that needs replacing. If anyone can help me identify how this front differential functions, I’d really appreciate it.

Thanks again for all the guidance.

— Matthew