Diff lock not working, is there anything easy to check first?

[lharrell799]

Today I was mowing around my creek. I managed to get my B2910 stuck in a precarious position. I was in some uneven terrain, and the rear right tire fell in a hole, and the left rear tire came off the ground about six inches. After I pulled my underwear out of my crack, I put it in reverse and tried to back out. Only the left rear (off the ground) would spin. I put it in 4 Low and tried to back out. I then realized the front right tire was off the ground and spinning. Next, I press on the diff lock, but got nothing. Still only the left rear (off the ground) would spin. I tried many times, and got nothing from the diff lock. Had it all the way to the floorboard. Is there something easy to check, or is this going to require opening up the diff. If it's the latter, I will probably just leave it alone.

I was able to get the tractor out. I ended up putting the FEL down, and lifting the front off the ground. This brought the left rear tire back to earth, and I was able to back out, while keeping the bucket down. Any help is appreciated.

 

[4570Man]

Check all the linkage to make sure it’s moving whatever it’s supposed to inside the case.

 

[Jim Nelson]

If it's like my B7800 you're probably looking at replacing internal parts. I posted on having to do mine twice but not tech savvy enough to find the threads. I have to use my dif lock a lot because of the steep slopes on our property, if you don't use yours a lot I would say leave it and just be careful.

I think your tractor is the predecessor to mine and probably the same design, which is pizz poor.There is what they call a clutch which is just a 2 pronged cog that rides on the axle and engages the differential cage when you step on the pedal. The clutch is much harder than the diff.cage unit is and it eats the diff.unit up. We all know where the money is. After the second time I did mine I checked everything very closely and found that most likely my problem came from the clutch not fully disengaging when I took my foot off the pedal.
The way this is set up, with the pedal on the left side of the floor and the engagement linkage on the right, there is way too much room for flex in the linkage and no adjustment to speak of. The only thing I found to do was lube up the axle shaft where the clutch slides on the axle, as it was dry before, and use spray lube on the rest of the exposed linkage on a regular basis. I'm also careful every time I take my foot off the pedal to be sure it has fully disengaged. This sometimes requires backing up just a bit to get it to release.
Hope this helps. As much as I like my Kubota I've found couple of places like this where the engineering is lacking.I'm sure it's true of all brands.

 

[lharrell799]

If it's like my B7800 you're probably looking at replacing internal parts. I posted on having to do mine twice but not tech savvy enough to find the threads. I have to use my dif lock a lot because of the steep slopes on our property, if you don't use yours a lot I would say leave it and just be careful.

I think your tractor is the predecessor to mine and probably the same design, which is pizz poor.There is what they call a clutch which is just a 2 pronged cog that rides on the axle and engages the differential cage when you step on the pedal. The clutch is much harder than the diff.cage unit is and it eats the diff.unit up. We all know where the money is. After the second time I did mine I checked everything very closely and found that most likely my problem came from the clutch not fully disengaging when I took my foot off the pedal.
The way this is set up, with the pedal on the left side of the floor and the engagement linkage on the right, there is way too much room for flex in the linkage and no adjustment to speak of. The only thing I found to do was lube up the axle shaft where the clutch slides on the axle, as it was dry before, and use spray lube on the rest of the exposed linkage on a regular basis. I'm also careful every time I take my foot off the pedal to be sure it has fully disengaged. This sometimes requires backing up just a bit to get it to release.
Hope this helps. As much as I like my Kubota I've found couple of places like this where the engineering is lacking.I'm sure it's true of all brands.

B7800 and B2910 are the same tractor. I think there are only a couple of differences. Cruise control, etc.

Did you fix your diff lock yourself, or the dealer. If you did it yourself, how hard was it.

 

[Dave M7040]

Go to this site and download the shop manual.

Index of Kubotabooks/Tractor Owners Manuals/

Unless you engaged the diff loc when things were spinning, it is hard to damage the mechanism. However, if you did then be prepared for work to remove the right side axle case.

Physically check the linkage under the floor first.

Dave M7040

 

[Jim Nelson]

I did my own and was really intimidated at first but soon found that it is all very simple.I took my time and lots of photos because I don't trust the manual to tell you everything. I would say the most important thing is to be meticulously clean including work area.I have a pretty nice old shop that is easy to keep clean and would never try this out in the dirt.
Contrary to what Dave said, and this is with all due respect to him and all his contributions to the forum, You do have to pull both axles to get the diff. cage out.

When you get to the point of taking it apart be very careful or you can open up a lot more than needed and spill bearings, gears,shims,and it is scary. I learned this the second time around when I had a young friend helping me who got impatient with me taking so long and jerked the rear case out spiking everything out. This assembly rides on 2 or 3 shafts and the fit is pretty tight so it takes time and patients to get it separated at the right spot.This was one place the manual came in real handy.
Please understand that I am not bad mouthing the manual and would never be without one but as I was told by an old Kubota parts man these books were printed assuming that the user has been through th company schools and has a good basic understanding of what he's doing.

 

[Henro]

Something you could try if this happens again, and your differential lock does not engage, is to use the rear brake on the wheel that is spinning. This should lock it and cause the other wheel to start turning...

Edit: I did not mean to totally lock the spinning wheel. Apply some brake to it and the other wheel may grab enough to get you out of trouble. Has worked for me in the past...