B7100 front axle oil question

[AOW162435]

I drained & refilled the front axle today: 3/4qt in the differential housing, and about 5oz in each gear housing.
Afterwards I realized the housing bolted to the axle also has drain & fill plugs. Is that its own chamber? Or does it share oil with the differential housing?

Andreas

 

[N3BP]

That's the front driveshaft U-joint housing. The drain is for water condensation. I'm pretty sure that bolt should be facing down. I think your housing needs rotated CCW by one boltset. Neither of my B7200's have that condensate drain, so Kubota must have determined it unnecessary.

 

[Lil Foot]

I have been told that very early B7100s had "open" cup bearings in the u-joint between the driveshaft & differential. They ran in an oil bath within that housing for lubrication. The housing was filled with oil until it ran out the fill plug. That style u-joint was soon replaced with a modern, grease-able joint, eliminating the need for the oil bath.
If the housing is rotated to place the plug on the bottom, it will no longer line up with the driveshaft.

 

[N3BP]

Thanks for the education Bill. I sold my B7100 years ago and didn't remember changing any oil in that housing. I did manage to find an old picture of mine and sure enough it did have a fill and drain plug...

 

[AOW162435]

Yes, the plug shown in my pic is the higher of the two.

I assume when I remove the drain plug, whatever comes out is from this chamber only?


Andreas

 

[Lil Foot]

Yes, the plug shown in my pic is the higher of the two.

I assume when I remove the drain plug, whatever comes out is from this chamber only?


Andreas

Theoretically, yes.
But I know when I rebuilt my front axle, I put that housing together dry, but some time later, I checked & there was some oil in there. I think some oil migrated from the differential after some STEEP uphill work I had done.

 

[AOW162435]

Theoretically, yes.
But I know when I rebuilt my front axle, I put that housing together dry, but some time later, I checked & there was some oil in there. I think some oil migrated from the differential after some STEEP uphill work I had done.

Thank you. You reassembled it without oil because you installed the new-style u-joint?

Andreas

 

[Lil Foot]

It already had it in, probably from the factory.
I have never seen one of the old style, and don't know of anyone who has, but an old, grizzled Kubota tech told me that was the reason for that housing/fill plug/drain plug.
Mine is a 1979, sold in 1980.
According to
https://www.tractordata.com/farm-tractors/001/2/7/1271-kubota-b7100.html
they started making B7100s in 1976.
I have the feeling the old style u-joint was phased out pretty early.

 

[AOW162435]

It already had it in, probably from the factory.
I have never seen one of the old style, and don't know of anyone who has, but an old, grizzled Kubota tech told me that was the reason for that housing/fill plug/drain plug.
Mine is a 1979, sold in 1980.
According to
https://www.tractordata.com/farm-tractors/001/2/7/1271-kubota-b7100.html
they started making B7100s in 1976.
I have the feeling the old style u-joint was phased out pretty early.

Excellent, thank you. My serial number is from 1979, so I guess my options are to simply drain & refill, or slide the rubber boot up to see which u-joint version I have.

Andreas