YM240D front axle leak repair progress post

[oksanaut]

Got a YM240D with FEL over a month ago - it looked very used, but worked great, and I really did not want to pass on a green one. I have been asking questions in another, more specific, topic, and figured I'd share overall progress here.

The 240 came with a long list of issues and, from lurking on the forum, I figured I could try to fix them (worst case scenario, I thought, I'd tow it to a nearby shop). I started with the worst problem on the tractor - wobbly and very leaky front end. Having the help I have got so far on the forum is very helpful and encouraging as the most mechanical experience I have had previously was working on old German cars 15 years ago.

It also came with an I&T manual, but I liked the original parts and service manuals that the YM155D came with, so I found those on eBay. Once I got the Service Manual, I realized that it doesn't cover 4WD front end at all, and I&T felt a little too condensed for me. I found a drivetrain manual, but have not received it yet - hopefully it will teach me some secrets not covered in the library I collected.

Here, in the garage, it looks a little bruised but in general nice and dry.


The inner side of the wheels:


I preemptively got some parts based on the parts diagram and tried to deduce how to take apart those hubs. PO probably did not realize that the front axle had three separate reservoirs and only checked level in the center because very little oil drained out of the knuckles (I've only had the tractor for 2 weeks prior to putting it on the stands). Not knowing that the knuckle comes out all at once and comes together like a puzzle, I did not order enough replacement seals/gaskets. Good thing that Hoye's shipments always make it in by Friday. While waiting we tried to clean up the parts and make sense of what we saw.







The unusual wear in the shims seemed very wrong, I posted about it, and there was a very insightful discussion here: http://www.tractorbynet.com/forums/yanmar/397659-ym240d-front-axle-shim-wear.html . So based on what I learned in that thread, I thought that I probably will need to re-measure and add more shims. I decided to do this without the knuckle body to get a nice clear view of how things were meshing together.

I cleaned up, painted, and re-assembled the knuckle cover with the stub axle to see how the gears are aligning (thanks to encouragement and advice from rScotty, winston1)



Here is the result of trying to figure out how mechanic's dye works. Not quite sure how to read this yet, to me it appears that the vertical gear could be closer, ie need more shims.


And cleaned up/started on the other side (this used to be a ball of oily dirt):


Will post an update when I am back at it (probably next weekend).

Advice, comments, all appreciated! Thank you

 

[winston1]

What was the backlash when you assembled and put on bluing?

 

[normde2001]

I would not be too concerned with backlash at the low speeds you are going to be using it, . Minimal backlash but free-turning is perfect. (Snug but free).

 

[oksanaut]

What was the backlash when you assembled and put on bluing?

I don't have a measurement I am comfortable with to share. Seemed very loose, I could rotate a few degrees before I heard a "click". What do you think?

 

[winston1]

I would tighten it up a bit.

 

[oksanaut]

I would tighten it up a bit.

Will do. Thank you for advice.

 

[rScotty]

Looking at your photos reminds me that I never did have good luck with that type of grease-based mechanic's dye. It was always too little, too much, or too difficult.

I prefer to use something similar but non-greasey. Something that dries fast, leaving a very thin coating easily rubbed away. My favorite is Dykem brand blue layout dye. It is basically blue dye in an acetone base. Dries in less than a minute, runs everywhere, and permanently dyes anything it touches. It rubs away easily. I find it easier to "read".

As a cheaper and more controllable alternative I've also used black or blue felt tipped pens. Give it a try.

Do any of your shop manuals show the typical wear patterns for bevel gear engagement? Some Yanmar manuals did, others did not.

If the backlash is a couple of degrees, that will work too. If you can set up a degree wheel you could convert degrees into thousanths of inches. It's doable, though dial indicator would be more accurate. I agree that what you are looking for mainly is to have some clearance and no binding - but if you can accomplish that while also putting the gear tooth torque onto the proper part of the gear then why not do it?
rScotty

 

[normde2001]

" I agree that what you are looking for mainly is to have some clearance and no binding"

In the cash register biz we called that "snug but free"
.

 

[oksanaut]

Looking at your photos reminds me that I never did have good luck with that type of grease-based mechanic's dye. It was always too little, too much, or too difficult.

I prefer to use something similar but non-greasey. Something that dries fast, leaving a very thin coating easily rubbed away. My favorite is Dykem brand blue layout dye. It is basically blue dye in an acetone base. Dries in less than a minute, runs everywhere, and permanently dyes anything it touches. It rubs away easily. I find it easier to "read".

As a cheaper and more controllable alternative I've also used black or blue felt tipped pens. Give it a try.

Do any of your shop manuals show the typical wear patterns for bevel gear engagement? Some Yanmar manuals did, others did not.

If the backlash is a couple of degrees, that will work too. If you can set up a degree wheel you could convert degrees into thousanths of inches. It's doable, though dial indicator would be more accurate. I agree that what you are looking for mainly is to have some clearance and no binding - but if you can accomplish that while also putting the gear tooth torque onto the proper part of the gear then why not do it?
rScotty

Heh, I had similar feelings about prussian blue. Found and ordered Dykem on Amazon, should come by Friday.

I noted that I need proper tools, but... researching how to use dial indicator on this type of gear and how to use it to measure backlash caused more confusion rather than clarified things for me. Any pointers/youtube videos/articles with good visuals are appreciated.

My shop manual has illustrations for this type of gear, but not in a section about front end (I also don't have that section in my service manual). It talks about things being too close or too far, but I didn't know how to use the dye correctly until I read How to Set up Your Rear Gear Correctly – RacingJunk News a few days later, so I did not quite grasp the meaning of what I saw at the time. This weekend we try again

 

[winston1]

Since you are going to be checking your backlash with the housing put together here is how I would do it. I would put a bolt in one of the stub axle holes that the wheel bolts to. That should be the appx diameter of the front drive gear. With your indicator fastened to housing with magnet base, c-clamp or whatever, then put the point of the indicator against the installed bolt. You can then measure the movement back and forth while feeling the gear contact. You need to be measuring at a distance close to the diameter of the front drive gear. Anything further will give a larger reading, anything closer will give a smaller reading. Hope this makes some sense to you.