Yanmar 155D Right Front Axle Assembly

[Berdo]

Again, we inherited this tractor. I never owned one before, and I’m not tractor-savvy. I was told the PO had flipped the tractor over on its right side some time ago. The PO rarely drove it. When I drove it, the RF wheel would go straight for a little while, then start hunting. The LF kept true, but the RF would kinda wander, badly, like probably 25 degrees, from the LF tire. Directional control was very difficult. Both L and R kingpins appear okay. Steering linkage is okay. Steering gearbox is okay. I separated the RF tie rod from the attachment, and then moved the RF tire through its entire L - R travel. I could feel an area of loose travel. No weird sounds or grinding. I’m afraid something inside of the front axle assembly is broken, or sheared, but I’m not sure. And I’m kind nervous about dismantling the whole assembly to go exploring. I’ve gotten the assembly somewhat apart, but am afraid to go much further until I gain bit of insight and confidence. Any thoughts?

(Photo shows assembly I’m trying to describe, except ours is the right side)

 

[bmaverick]

Again, we inherited this tractor. I never owned one before, and I’m not tractor-savvy. I was told the PO had flipped the tractor over on its right side some time ago. The PO rarely drove it. When I drove it, the RF wheel would go straight for a little while, then start hunting. The LF kept true, but the RF would kinda wander, badly, like probably 25 degrees, from the LF tire. Directional control was very difficult. Both L and R kingpins appear okay. Steering linkage is okay. Steering gearbox is okay. I separated the RF tie rod from the attachment, and then moved the RF tire through its entire L - R travel. I could feel an area of loose travel. No weird sounds or grinding. I’m afraid something inside of the front axle assembly is broken, or sheared, but I’m not sure. And I’m kind nervous about dismantling the whole assembly to go exploring. I’ve gotten the assembly somewhat apart, but am afraid to go much further until I gain bit of insight and confidence. Any thoughts?

(Photo shows assembly I’m trying to describe, except ours is the right side)

sooo, you are saying this then.

 

[ponytug]

Again, we inherited this tractor. I never owned one before, and I’m not tractor-savvy. I was told the PO had flipped the tractor over on its right side some time ago. The PO rarely drove it. When I drove it, the RF wheel would go straight for a little while, then start hunting. The LF kept true, but the RF would kinda wander, badly, like probably 25 degrees, from the LF tire. Directional control was very difficult. Both L and R kingpins appear okay. Steering linkage is okay. Steering gearbox is okay. I separated the RF tie rod from the attachment, and then moved the RF tire through its entire L - R travel. I could feel an area of loose travel. No weird sounds or grinding. I’m afraid something inside of the front axle assembly is broken, or sheared, but I’m not sure. And I’m kind nervous about dismantling the whole assembly to go exploring. I’ve gotten the assembly somewhat apart, but am afraid to go much further until I gain bit of insight and confidence. Any thoughts?

(Photo shows assembly I’m trying to describe, except ours is the right side)

So how far have you gotten the assembly apart? Have you pulled the knuckle arm off? When you have the front wheel off the ground how much can you pull it in/out? Is it leaking oil?

There are a few videos on YouTube on 4wd tractor front knuckle disassembly to help you get the lay of land, so to speak...I think "Marty T" did one awhile back. Not a Yanmar, but similar design.

All the best,

Peter

 

[winston1]

Splitting at the knuckle is not complicated. After that it can be. Yanmar KNuckle Seal Replacement Instructions.

 

[California]

I was told the PO had flipped the tractor over on its right side some time ago. ... the RF would kinda wander, badly, like probably 25 degrees

I don't understand how the wheel can wobble that far when the tie rod is intact. Anybody have an explanation?

 

[Harry in Ky]

My guess is the item labeled knuckle arm (L) is loose on the spindle (or whatever part it's attached to) as in a sheared key, damaged splines, etc. Whatever locates in place.

 

[California]

My guess is the item labeled knuckle arm (L) is loose on the spindle (or whatever part it's attached to) as in a sheared key, damaged splines, etc. Whatever locates in place.

That makes more sense than massive internal damage. And would be far simpler to remedy.

Weld it back together!

 

[Dman1981]

If it’s already broke how much worse can you make it
There is so much information online
And e books available buy one read up on it and tear it apart
A good mechanic never says can’t
Just bad engineers

 

[Berdo]

sooo, you are saying this then.

View attachment 834348

All I need to do is turn the tractor around 180 degrees…

 

[Berdo]

So how far have you gotten the assembly apart? Have you pulled the knuckle arm off? When you have the front wheel off the ground how much can you pull it in/out? Is it leaking oil?

There are a few videos on YouTube on 4wd tractor front knuckle disassembly to help you get the lay of land, so to speak...I think "Marty T" did one awhile back. Not a Yanmar, but similar design.

All the best,

Peter

The assembly is off the axle. I have not yet split the knuckle (I think that means to separate the upper and lower half?). When off the ground, the wheel did not slide in or out at all. No oil leaks. With the tie rod disconnected, the steering wheel and left assembly operate smoothly. I’ll give the video a look. Thank you for your reply.

 

[Berdo]

I don't understand how the wheel can wobble that far when the tie rod is intact. Anybody have an explanation?

I agree. It doesn’t make sense. I see no trauma to any of the steering linkage or kingpin, which appears secure.

 

[Berdo]

My guess is the item labeled knuckle arm (L) is loose on the spindle (or whatever part it's attached to) as in a sheared key, damaged splines, etc. Whatever locates in place.

I wish and hope it ends up being that simple. Unfortunately, it appears the knuckle is secure on its spindle. So far, from what I can see inside of the assembly, there are no damaged gears, or splines, shards, etc. But, as Ponytug referenced, I’ve not yet separated the upper and lower halves.

 

[Berdo]

If it’s already broke how much worse can you make it
There is so much information online
And e books available buy one read up on it and tear it apart
A good mechanic never says can’t
Just bad engineers

I’m not a mechanic or an engineer. I’m in big trouble

I have been researching online, but no direct hits. I got a service manual from Hoye Tractor, but it seems very general.

I‘ll probably end up diving in the rest of the way. Like you say, it’s already broken. What else could possibly go wrong? Ha. I think you all are going to find my experimentation very entertaining.

 

[Berdo]

That makes more sense than massive internal damage. And would be far simpler to remedy.

Weld it back together!

I’m probably better with a cutting torch. For the sake of this tractor, I hope I can get it fixed.

 

[Berdo]

So how far have you gotten the assembly apart? Have you pulled the knuckle arm off? When you have the front wheel off the ground how much can you pull it in/out? Is it leaking oil?

There are a few videos on YouTube on 4wd tractor front knuckle disassembly to help you get the lay of land, so to speak...I think "Marty T" did one awhile back. Not a Yanmar, but similar design.

All the best,

Peter

So, I watched some YouTube disassembly and reassembly videos (stumbled upon a cute, jiggly girl giving narratives while driving her own tractor along bumpy trails). Back to task, I split the assembly. Damned if all doesn’t look just fine. All gears and bearings look just fine. Key was in place. No metal or other wreckage anywhere within the assembly. I’m stumped, and think I’ve made a mechanical mountain out of a molehill. I’m awaiting gaskets and seals from Hoye Tractor (they’ve been awesome), and will piece it all together and see what happens. Then start anew.

The photo below was taken for fun shortly after we took possession of, but before I started working on, the tractor. In it, I think you can almost see the RF tire skews outward. I thought it was just an alignment problem, so I adjusted the tie rod end accordingly, until straight. No good. When I took it for a test drive, the RF wheel went crooked again. Worse than in this photo.

 

[California]

Wow, I see a front hydraulic pump. Those are rare and expensive!

 

[Harry in Ky]

I'm not buying that. If the steering wouldn't hold on that side to the point where the tire and wheel would turn left and right while the steering wheel and tire on the other side had integrity, then something's wrong. You just haven't found it yet.

 

[Dman1981]

did you lift
Front end off the ground and try moving stuff around with a bar safety first of course jacksrands are mechanics friend or a huge flat log

 

[Berdo]

I'm not buying that. If the steering wouldn't hold on that side to the point where the tire and wheel would turn left and right while the steering wheel and tire on the other side had integrity, then something's wrong. You just haven't found it yet.

I completely agree. Yet after I isolated/disconnected the RF assembly from the tie rod, there was still a loose area of travel. I don’t know what else it could be, which is why I investigated the RF assembly in the first place. It’s probably something very simple that I’ve overlooked - although there’s not a lot that I can think of that could cause such a problem, especially when the assembly is isolated.

 

[Berdo]

did you lift
Front end off the ground and try moving stuff around with a bar safety first of course jacksrands are mechanics friend or a huge flat log

Yes. All of the linkages and connectors look secure.