4WD Rear axle mount grease

kingreboog · Dec 5, 2021

While doing routine greasing on a MX5800 I noticed a grease fitting on the mount at the rear of the front axel. Didn’t see any reference in the owner manual. No vent plug on opposite side from Zerk like the front axel mount. Won’t accept but the smallest amount of grease.
What’s going on here?

rScotty · Dec 5, 2021

At the pivot in the center of the axle? The M59 has an adjustment for pivot wear at the front of the pivot and two zerks - one in front and one to the rear.

OK, I looked it up and sure enough the MX5800 has basically the same front axle design.
I see what you mean by the front having a vent #120 but not the rear.

And then there is that odd plug #20. What the heck is that?
I don't know quite what is going on there. Maybe we can figure it out.
Here is a link to the exploded diagram:

Kubota MX5800H (4WD HST TRACTOR W/FOLDABLE ROPS) Parts Diagrams

Kubota Parts Catalog Lookup. Buy Kubota Parts Online & Save!

www.messicks.com

rScotty · Dec 5, 2021

BTW, here is the M59 front axle. Interesting that on this one I can't see any grease vents on the exploded diagram, but I'll look there tomorrow.

Kubota M59 Parts Diagrams

Kubota Parts Catalog Lookup. Buy Kubota Parts Online & Save!

www.messicks.com

It's a separate venting issue completely, but I see that this diagram shows that the front drive axle of the M59 is vented up to the frame while the MX5800 diagram doesn't show an front axle casting vent. It must have one...

ricksheehy · Dec 6, 2021

Since I was unsuccessful injecting grease, I tried removing the Zerk fitting to test it’s function. Could not budge it. This is going to keep up at night.

rScotty · Dec 6, 2021

ricksheehy said:
Since I was unsuccessful injecting grease, I tried removing the Zerk fitting to test it’s function. Could not budge it. This is going to keep up at night.

I wonder how many owners do grease those two fittings and also make the front axle play adjustment?

Kubota must have thought that pivot was important because there is a surprising amount of sophiticated parts, fits, and engineering that went into that simple axle pivot. It's hardly mentioned in the manual.

In case you do get those two "front axle support" zerks lubed, there are a couple more zerks down there that are part of the 4wd that you may not have found...I found them on a European maintenance chart for our tractors where it mentions something they call "front axle gear case supports" and says there are two zerks. It is one of the few places that Kubota specifically calls for moly EP grease, and I'm not even sure I've ever greased it.
rScotty