More on leaking axle seals and vents

[arrabil]

I think your venting scheme will only work if you have TWO vents, one on each side

I was thinking that too. Or on top of the pumpkin.

And I already have an answer as to whether 3/8" hose is fat enough to allow air to escape past the oil and overcome the capillarity/surface tension. No, of course not. Otherwise the oil wouldn't be in the filter in my pictures! And there wouldn't have been anything to drain.

Thats a shame.... I just found an expansion tank in my trash can.... the fuel tank from a broken, 10 year old Ryobi trimmer I took apart a couple months ago.

I'm going to give this some more thought. A day or two until I get my seat back on the tractor anyway. But I think I'm going back to the sealed axle pending any light bulbs from anyone.

 

[dfkrug]

I was thinking that too. (

Drilling a hole in the top of the axle housing on the other side is not a
big job. If you remove the kingpin/hub assembly, you can collect any
shavings you create. You would want both vent hoses to go all the
way up to your expansion tank, however. Good you are using 3/8"
hose, and not 1/4" or less.

I still don't like that low-vis hyd oil in there.

 

[arrabil]

No, I didn't think it would be a big job either except for the disassembly of the axle. Remind me again what fluid you use? Maybe I should just spend two days on this and be done with it. I don't even think an overflow is needed with two vents.

If they made different gear ratios for the front axle so I could put bigger tires on the front for better stability, I would take the axle apart tomorrow and start on this.

 

[nmu98]

Arrabil,
Not only is the size of the hose going to have to be larger, the size of the hole going into the axle is going to have to match it. That could be bad as far as opening it up for contamination. Also, make sure you vent your expansion tank

 

[Spudland_Dave]

I still don't like that low-vis hyd oil in there.

When it came time to do my 100 hour change I asked my dealership about this very topic (I'm old school and thought the same as you)....from what they told me...they used to specify 80w90 gear oil in the axles...and had alot of axle failures....Exactly what kind of failure and why I dunno..but JD then redesigned the front axles and went with HyGard. Since then, failures have been minimal. Also pointed out you should use what oil it was designed for... Even the "big boy tractors" now specify HyGard. When chatting about it, he mentioned some model CUT (I didnt pay attention because it didnt affect me) that actually had a Serial Number break on the axles...one was the "80w90 version", the other a HyGard version...

So...Could be totally unrelated...Just throwing it out there...but maybe all these seal failures we're hearing about are on the "older gen" axles, or are from people running 80w90 in their HyGard axles...or vice versa...

As a side note....My dealer said if I was that concerned with the Lo-Vis HyGard in there, its perfectly OK to use Normal HyGard...but in my climate its a debatable because of the cold winters.

 

[arrabil]

one was the "80w90 version", the other a HyGard version...

I'm not buying it at face value. Why would that be true on its own? There has to be an engineering reason for it. Like on a Mazda M5OD transmission. They are specified for ATF and not MTF because they gears are much closer together and so the much thicker MTF doesn't get in the gaps effectively.

So on our axles, are the bearing tolerances tighter? The ring/pinion backlash (0.004-0.0012) isn't any tighter than the axles I normally work on. They totally over-fill the axle so it isn't because the lighter weight oil splashes better. Is something in the wheel hub such a tight tolerance? I don't know but its just hard to believe without knowing why....

 

[Spudland_Dave]

I'm not buying it at face value. Why would that be true on its own? There has to be an engineering reason for it. Like on a Mazda M5OD transmission. They are specified for ATF and not MTF because they gears are much closer together and so the much thicker MTF doesn't get in the gaps effectively.

So on our axles, are the bearing tolerances tighter? The ring/pinion backlash (0.004-0.0012) isn't any tighter than the axles I normally work on. They totally over-fill the axle so it isn't because the lighter weight oil splashes better. Is something in the wheel hub such a tight tolerance? I don't know but its just hard to believe without knowing why....

Hey, I agree with you....I'm from the "if it goes into a pumpkin or gearbox it should be gear oil" camp....Which is why I asked about it in the first place.
Spoke with my BIL about it as he's a Field Tech for CAT and they're doing the same as Deere and going to "2 oil" machines....Engine Oil and Hydraulic Oil...

SO...all that being said, you briefly mentioned it..Deere might just be "overfilling" the cases to compesnate for the thinner fluid. Maybe the true fix here is filling the front end with 80w90 and getting a longer dipstick :confused2:
I'd like to talk to an engineer over at Spicer in regards to this front end....

 

[dfkrug]

No, I didn't think it would be a big job either except for the disassembly of the axle. Remind me again what fluid you use? Maybe I should just spend two days on this and be done with it. I don't even think an overflow is needed with two vents.

If two vents work like I think they should, I agree you will not need an
overflow tank. Now you see why the designer opted to tolerate the
the pressure spikes inside the axles, rather than deal with trouble-prone
venting. As an aside, my ATV has a vented rear final drive & the vent hose
goes all the way up to the handle bars. As the unit got older, the vent
hose cracked down by the final drive, and it took in a lot of water.

I use GL-5 gear oil. We went thru this before when I posted about
rebuilding my early 4300 axle.

I know this is offensive to JD true believers who want to use the hyd oil
specced in the manuals (J20C or J20D). I made this change for several
reasons: I was concerned about the corrosion I saw in my axle, after
9 y of THF being in there. There have been lots of changes to this axle
in just the 4 or 5 years of production. All seem to be made by Spicer (the
inventor of the U-joint), though the earliest ones are unmarked. They are
not made by Deere. OTOH, Kubota and DaeDong do seem to make their
own MFWD axles, and both spec gear oil, and both companies have very
reliable axles. I have not met any JD engineer or other employee who knows
anything about the lube choices they made. (I do ask them at the giant
exhibits at the tractor shows.) I am more comfortable using gear oil for
this low speed conventional gear final drive, but everyone should make
their own choice.

As for the access to inside that axle, that only requires removal of the
4 bolts (photo), and possibly the tie rod end. The shaft slides right out.
You can see the dipstick in there.

 

[arrabil]

I use GL-5 gear oil. We went thru this before when I posted about rebuilding my early 4300 axle.

I remember going through it, I just couldn't find where and the conclusion!

going to "2 oil" machines

See, thats the answer as to why they spec HyGard. Its likely significantly cheaper to have one oil dispenser during assembly than two. Some accountant came up with it and an engineer was told to recalculate the amount need in the axle to achieve equivalent results.

Maybe the true fix here is filling the front end with 80w90 and getting a longer dipstick

I'm changing my previous stance I took with dfkrug and saying that I think you're right. I just may try it...

Thats a great picture, btw!

 

[nmu98]

So how much 80/90 is correct for these axles?

It still has to be filled enough to lube the center and both sides. How much of a difference are we talking?