YM240D front axle shim wear

oksanaut · Jun 22, 2018

rScotty said:
OK, I'm with you now. I think from your photo that you are working on the wheel spindle.

Some more on shop manual and parts books: I got to looking at my books, and like you I have the OEM green Yanmar 240D parts book. I also have what sounds like the same I&T Shop manual covering the 240D plus other models. In addition, I have other shop manuals for other model Yanmars....but nothing else specifically for the 240D.

The original green Yanmar parts manual is good; I've rarely ever found those Yanmar parts books to be in error - although sometimes (rarely) Yanmar sent out addendums & errata to be added to some pages. The problem with the Yanmar parts books is that they specify dimensions on some parts but not others. They are pretty good on some collars, but not so much on spacers and bushings. The good thing is that when they call out dimensions I've found them to be accurate. And they are very good with bearings and bolt sizes.
Yanmar's OEM shop manuals are equally good and have more dimensions, but I don't have one for the 240D. And the OEM shop manuals are very model specific. They will cover variations within a model but for example the YM240 shop manual will not normally have the 4wd axle chapter. For that info, you have to have the YM240D shop manual.

As to the I&T manuals, they have good illustrations and a decent write up, but as you have probably already figured out they don't do a very good job in their index and lists that refer back to the drawings. Index numbers point to the wrong part, or no part, and their dimensions may be wrong, too. At every step, take the I&T manuals with a grain of salt. Admirable effort, but they tried to do too much.

If you can, get an OEM 240D shop manual. It has to cover the "D" model for 4wd info. I'll look around too.

Uh-Oh...BTW, my apologies about my rant about bearing prices.... I didn't realize just how much heavier the 240D axle is than the 195D front axle. The bearings are NOT $12.00 bearings - the 240D uses one each of the #6008 and 6211 in the spindle area - which are more on the order of $36.00 each. Here's a link to bearing dimensions and specs that is informative and might help calculating shim size, too.
McMaster-Carr

If you are working on the spindle like I think you are, how are you coming on the oil seal? From the drawing it looks like Yanmar cleverly put a wear sleeve (collar) between the ID of the oil seal and the spindle stub axle. Of course doing that creates another leak path, which they addressed with a hidden O ring inside the wear sleeve and what looks to be a groove to hold it in the spindle stub axle. Hmm....well, they got that half right. A single O ring would stop but also needs something to keep the wear sleeve from cocking relative to the axle shaft. They could use either another O ring, or maybe very careful sleeve dimensions so that it gets sandwiched and stays parallel with the axle because of that. If yours weeps a little when you are done we can put some more thought into improving the oil sealing on the inside ID of that wear collar.

Keep notes of the dimensions of sleeves, collars, bearings and such - I bet we will need them before done. Plus I'd like to put notes in my parts manual.
luck,
rScotty

Yup, working on front (stub) axle/wheel spindle that lives in the knuckle.

I have all the shop manuals, but had a hard time finding original for YM240D on eBay, so purchased one for YM240 two weeks ago. I also purchased a drivetrain manual for 135 through 240. I have to see what it turns out to be.

Like you said, t he oil seal (6) on the spindle seals around the wear collar (3) and housing cover (4). It had to be pressed into the housing cover (4). The wear collar had to be pressed onto axle (1) and o-ring (2).

I wonder if doubling up o-rings around axle would help. It is not covered in any literature I have, so I pushed o-ring all the way down on the axle and then pressed wear collar over it (the machined side down), I wonder if that would cause more of a problem. When I took it apart, the wear collar freely rotated on the axle and moved up-down about 3/16".

Here is the old wear collar for reference (here you can see the machined side)

I will measure all diameters (old and new appear to be exactly same, except the seal) and post them here.

winston1 said:
BEARING _: Yanmar Tractor Parts

BEARING _: Yanmar Tractor Parts

Those are the bearings I bought. Pulled a seal on one side on each.

rScotty · Jun 23, 2018

oksanaut said:
Yup, working on front (stub) axle/wheel spindle that lives in the knuckle.

I have all the shop manuals, but had a hard time finding original for YM240D on eBay, so purchased one for YM240 two weeks ago. I also purchased a drivetrain manual for 135 through 240. I have to see what it turns out to be.

Like you said, t he oil seal (6) on the spindle seals around the wear collar (3) and housing cover (4). It had to be pressed into the housing cover (4). The wear collar had to be pressed onto axle (1) and o-ring (2).
View attachment 559608

I wonder if doubling up o-rings around axle would help. It is not covered in any literature I have, so I pushed o-ring all the way down on the axle and then pressed wear collar over it (the machined side down), I wonder if that would cause more of a problem. When I took it apart, the wear collar freely rotated on the axle and moved up-down about 3/16".

Here is the old wear collar for reference (here you can see the machined side)
View attachment 559612

I will measure all diameters (old and new appear to be exactly same, except the seal) and post them here.

Those are the bearings I bought. Pulled a seal on one side on each.

Great! Glad you got those books. I'm very curious about the drivetrain manual you purchased. Is it a Yanmar publication? Yanmar did publish some technical manuals when they first came into the USA. But I only have one electrical one. I can't imagine what compelled Yanmar to write those kind of general technical shop manuals. It's like they were expecting to set up some technician schools and wanted to teach basic science, too.

Sort of like JD had done in the past some 20 years earlier in their FOS (Fundamentals of Service) series written for their ag tech schools.

The one such manual I have by Yanmar is on tractor electrical systems & reads more like the kind of book you would expect to find in an adult education class or some sort of technical school. It is fairly technical, but not specific to any model. Instead, it goes into the physics of electricity in their tractors in general.

O-RINGS:
Changing the subject now on to doubling up O-rings....my apologies for that. I didn't explain it very well. What I was doing was speculating on how Yanmar's wear sleeve could be improved. An additional O ring to prevent the wear sleeve from cocking on the axle shaft would necessarily require cutting another O ring groove in the axle shaft. And it would also need to be as far from the existing O ring as possible. It's just a speculation....please don't take me too seriously.

But here is how I got there: Stepping back a little, we mechanics know that most times when axles exit a housing with oil and precision parts inside we can expect to find an oil seal in the expected location. You just come to expect to see an oil seal there to keep the oil inside and the dirt outside. But the common design philosophy for just about every other similar axle and housing combo in the world is for the inner diameter of the oil seal to bear directly on a polished surface of the axle itself. It's the werar sleeve that startled me; a wear sleeve is an unusual thing to see in that location.

But for whatever reason, Yanmar put a wear sleeve there. Only problem with doing that is by inserting a wear sleeve between the oil seal and the axle itself, Yanmar solved the potential worrysome problem of a muddy oil seal causing wear on an expensive axle, but at the same time they also created a second leakage path....another way for oil to get out onto the wheel and dirt to get into the axle. With the wear sleeve, it becomes possible for oil and dirt to pass between the ID of the wear sleeve and the OD of the axle. That problem just just jumped out of the illustration at me when I first noticed that wear sleeve and started thinking about why it was unusual to see such a sleeve on car and truck axles....or on tractor rear axles for that matter.

So I started thinking about Yanmar's solution - that single O ring - and what problems trying to block the new leakage path with a single O ring would then cause. And it turns out that a single O ring can't help but make us need to think about keeping the wear sleeve itself from cocking on the axle. Probably if cocking happens the the inner O ring can still do it's job, but the original Outer Oil Seal would then have to trace a spiral path on the OD of the wear sleeve instead of a simple concentric path... and oops, that's not the best answer either. From the parts list it looked as though Yanmar quit at that point with the problem only half solved and I was just sort of speculating on ways it might be addressed if it ever did become necessary to redesign that part. You know....to improve the way it works...

Another possible solution is to have the wear sleeve fit very tightly on the axle shaft...but then how does one get the sleeve pressed over the O ring? Hmm....although we could modify that last idea by having the wear sleeve fit very tightly on the axle for most of it's length, yet have a larger diameter pocket for the O ring cut into one end of the wear sleeve. I liked that idea - still do in fact - but it also means that the wear sleeve needs to be shimmed endwise pretty carefully to get the O ring to sit within the pocket just right. So which one was it? What did Yanmar do?? The illustration in the book didn't give me a clue. Thanks to your photo with your post here, I can now see that Yanmar did use the latter solution. Of course that solution doesn't work unless the wear sleeve ID is very nearly the axle OD for at least some of it's length. And the wear sleeve has to be constrained by a good enough fit to keep it from moving endwise more than about half the depth of the machined pocket.

To me, that's the fun part of doing mechanical repairs - speculating on how the design got to be what it is and how it is supposed to work and what does that mean to my repair? Is there any unusual wear that needs fixing? Does it need any simple improvements? What is special about the design that I need to be thinking about??

Apologies if it was confusing. I'll try to be more specific.
It looks to me like you are doing a good job on that axle.
rScotty