Yanmar 187D - 4WD just quit on me

[284 International]

I have never been known to do things the easy way, or even the smartest way. I went outside during a commercial break for the Superbowl and looked at my 186D. It appears to be very similar, if not identical, to yours in respect to these parts. I don't know how mechanical you are or are not, so take this for what it's worth.

I would jack the front of the tractor up, and pull the front axle off. Since the driveline is off, all you'll need to do is disconnect the steering linkage and pull the pivot pin. Now you can at least work on the thing in a fashion that doesn't involve looking at everything upside down and on your back.

If you decide you need four wheel drive, I would definitely pull the axle apart, clean out broken parts and inspect the gears and bearings.

I'd pull the pinion out of the holder. Open those tabs on the lock washer up, and unscrew the nut while the pinion holder is as mounted as it can be into the axle housing. You'll probably want to use an impact wrench, because the torque specification is likely very high, and you don't want to break or damage the housing only using two bolts through the pinion holder.

I wouldn't worry about the backlash getting out of alignment because you took the pinion out of its holder. It will be a normal item of service for axle rebuilds on equipment like this. Any gear shop will be able to set it for you if you don't feel like it, or, maybe better, take it over to the local high school that has auto shop class. Students, at least here, rarely get to do powertrain things like that, since it's fairly rare. The teacher may be happy to set some of his students on it just to let them get experience.

You may be able to source a new pinion holder fairly easily. A dealer will be able to tell you if they interchange with a 186D and/or a 1510. That's the preferred choice, of course. Barring that, it should be a fairly straightforward piece for a machinist or decent fabricator to build you. I wouldn't even bother trying to make a collar out of some composite material.

I may be wrong, but I really don't see that working. Unless you broke it by dropping off a ledge, or driving onto a big rock or stump where the tractor was high centered on the pinion holder, there's too much force involved to retain that pinion holder for a wrapped sleeve of something to secure it. That's only my opinion though, it may work swimmingly.

If you can't source a replacement , or can't find one that's affordable, look for a local welding or fabrication shop. A good choice would be a place that has a bunch of ratty-looking Toyota or Jeep 4x4s. Take your axle and pinion holder to them. They will be able to fix it. Possibly the right fix will be to cut some pieces of tubing just bigger than the diameter of the bolt (say, .090 wall 5/8 tubing), then weld some gussets from those back to the housing of the pinion holder, then run some longer bolts through that assembly. They will know what to do, though, and be reasonably priced.

I wish I had a quick answer, but with this situation I don't see one. These tractors are, relatively, simple to work on. Give it a try. If all else fails, pull the 4 wheel drive guts out of it and use it in 2 wheel drive. :thumbsup: I imagine you'll be able to source parts though, or get something to work with your broken pieces.

 

[California]

If it turns out parts for it don't exist ...

That's a great idea on the offroader's welding shop. You could just carry the complete axle assembly in. They will know what works.

 

[clemsonfor]

Thanks Winston1 and California. I tried to work that bearing out through the hole - they are nearly the same size but it wouldn't come through. I may try one more time. The strap idea may work. There's a little "meat" on the pinion holder left that the strap could grab. The other thing I might try is to fabricate a collar around the pinion holder, and make it out of epoxy resin and carbon fiber or Kevlar fiber. With longer bolts it might work.

The other thought is to simply weld the pinion holder to the axle casing. I know this sounds weird but if it ever has to come apart again the weld can be ground off. As long as the rubber O-ring seal doesn't get cooked from the welding this might work. Maybe a MIG or TIG welder would run cool enough.

Please let me know if either idea makes sense. Getting the tractor to a shop involves 40 miles of driving with a trailer, and I don't have a trailer.

Getting the pinion holder off the shaft by removing the rear nut looked risky- the nut is held in place by a special washer that engages the shaft spline groove. The washer has six tabs that are folded up against the six faces of the nut so it cannot turn. I'm guessing that this nut also controls how far in or out the pinion gear is set against a bevel gear. In other words it's a factory-set tolerance.

A good weld should penetrate all the way through so a surface grinding shouls not "remove the weld". Also to weld that size flange you will cook what everis in that axle as well as the seal. My little tiny hobby mig welder will get what ever its welding red hot.

 

[DWeinreich]

I'm going to try repairing the broken off ears by welding them back on using a nickel based welding rod. Will check in after the attempt works or doesn't.

 

[284 International]

It's possible that may work, especially if it broke because of being hit on something. If it sheared those ears off because the pinion gear was trying to climb the ring gear, then it's probably not going to turn out well. If you baby it, things may turn out fine.

Do you remember dropping onto something, or backing into something that caught the tractor? Hopefully that's what broke it, and your repair will hold. Good luck, and thanks for letting us know what happened, and how it goes in the future. Out of curiosity, how did you come to the decision to fix it this way?

 

[California]

I'm going to try repairing the broken off ears by welding them back on using a nickel based welding rod.

I used nickel rod once and it turned out well.

My wife inherited cast iron garden furniture with several leg-attach tabs broken off. These tabs were thin, in my opinion under-designed. This low-grade decorative cast iron surely isn't as good a grade of iron as what you are working on.

Here are couple of posts with photos from 2007. The furniture is still in use without anything breaking.

Cast iron garden furniture.

Leg tabs re-welded detail photo.

If I can do this with no experience and an old AC welder, you should have a decent chance of success.

Listen to the pros, not to me, but what worked for me was to grind down my cobbled welds and reweld anything that looked doubtful until grinding showed clean flat metal. V the joints before starting. Cast iron can't take much heat before it crystallizes next to the weld so stop and let it cool. Grind out anything that doesn't look professional. Hopefully you already have more experience than what I started this project with!

Good luck on this.

 

[DWeinreich]

I decided to try the nickel rod arc weld repair because it is difficult and time consuming to take the tractor to a shop. I did a bunch of welding years ago and hope its like riding a bike, you don't forget how.

My guess is that the pinion holder flange broke when the tractor "dropped" on a mound of icy snow. All the weight of the tractor must have been on it. So, it looks like an external cause and not a gear malfunction.

I've got a reassembly question for this forum- between the pinion holder and the axle case's machined surfaces there were four long, narrow, thin metal shims with slotted holes so they line up with the four mounting bolts. What are these for? Do they adjust the in-out of the pinion shaft? Do they correct angular misalignment of the pinion shaft to line it back up with the centerline of the drivetrain? I lost track of which side the shims were on though I think they were evenly distributed. The shims don't show up in the parts diagram in the first post.

Also any advice as to how to separate the pinion shaft from the pinion bearing would be appreciated.

 

[winston1]

Should be the same amount of shims on both sides. I believe these shims are for adjusting backlash on the pinion/ring gear. After studying the John Deere 650 set up I see there is a spacer between the two bearings on the pinion shaft so the outer nut would be tightened and not used for adjustment. If you want to remove the bearings and the big one won't come through the differential housing you are going to have to remove that outer nut and snap ring in front of the outer bearing. The housing should then slide off the shaft. I really don't think you are going to screw up any clearances by doing this. The shims are the only thing that will. OK, this is my opinion, do not have a manual on your tractor.

 

[normde2001]

"When I hold the pinion holder tight to its seat (just tested this with the two remaining bolts torques down and the shims, about 1mm, removed) all the gears seemed to mesh."

Judging by that, it's a good bet the bolts just backed out. If the upper bolts had not been loose the top flanges would have broken also. A couple major salvage yards are wkytp.com and southern-global.com.

 

[normde2001]

Those shims are for adjusting pinion depth and alignment, as on a car rear differential, just not as critical due to the low speeds. You really should get a service manual, or read up on differential set up in general.