I didn't even get half out before it stopped dripping out. Any harm in running it over-full?
OOps, but no harm done in the short term. Uh....Did you remove all three of the front axle drain plugs? There's one one drain for the main axle plus one each for each side bevel gear tower gear assembly. The system should have drained fine unless one or both of the tower gear assembly is vapor-locked for some odd reason. But vapor lock there is rare. The reason why it is rare nowdays is that designers have learned to make vent that area. Sometimes the outboard ball bearing on the axle where it enters the bevel tower gear assembly is unshielded type specifically to allow for venting between the three otherwise separated volumes. Othertimes, there is a connecting passage in the housing itself. The unshielded bearing solution is the more common one because it eliminates one potential lead. However they do it, some provision needs to be made for equalizing the pressures. I haven't taken an
M59 front axle apart so don't know how Kubota did it on our tractors.
The rule of thumb for lube height on this type of splash lubricated front end is common sense: It needs to be high enough to keep everything splashed with oil, but not high as to block the air venting between the various internal plenums (chambers)....and especially not high enough to block the vent connection to the outside air.
I don't know where any of these items are located in the
M59 front axle, but if it were me I'd start my design by defining a low/high lube oil height that always touched the main transverse front axle and never did entirely bury that axle in oil. Next I'd check that the proposed oil height was OK for venting and for lubing the various bearing surfaces at all angles of tractor lean. Then I'd look at temperature, types of friction surfaces, and finally at compatibility with the seal chemistry. I remember when hypoidal lubes first came out that the seal chemistry problem bit a lot of us in the butt.
OK, I just went out and checked the dip stick on mine and it looks like the Kubota designer chose the same oil depth that I would have.....so maybe the rest of his design philosophy is similar too. Afterall, it's a pretty common solution. This is gear and bearing engineering; not rocket science.
Anyway, that would mean that the front end oil level is important - although more for venting and sealing reasons than for friction reasons.
Bottom line is I would drain it down to the recommended level before the summer and hot operation..... and particularly before using it where the front wheels may be in deep water or in deep mud. The reason for that is "case panting". Snow is probably OK. So I wouldn't exactly go rushing out to do it...but I'd sure remember to do it.
no problems....rScotty
