B21 "pop/clunk". In drive line?

[joea]

Once in a while have experienced a "pop/clunk" and a bit of a "jerk" when starting out and just rolling slowly.

Could be my imagination, or being on gravel, but is seems a bit "bumpy" too. It only does it occasionally, not constantly or consistent with any particular motion, maybe when turning a bit.

Cannot see any coincident motion of the steering mechanism from the seat and, of course, cannot see the drive shaft, as I call it, which is what I suspect/hope it may be. Reasons being, cost aside, the sound is not muffled at all, the "boot" on the shaft was torn for a while before I noticed it and "fixed it", operating in dirt and gravel. When I changed fluid and filters not long ago and it was clean, no metal at all and it was clean.

Once it does that a couple times I can get on with what I was planning and it seems fine, but, I worry that I am creating a bigger problem by not dealing with it now.

 

[North Idaho Wolfman]

Lift the front wheels off the ground, have 4wd disengaged and turn, listen, and feel.

 

[Edke6bnl]

Couldn't it just be the 4x4 binding. Does it do it in 2wd?

 

[joea]

It does it in 2WD. I just tested that. Leaves out the front propeller shaft entirely. I'm now thinking it must be the rear axle or differential.

Cannot make it do it "on demand", such as coming to a full stop, reversing, and going forward again, or doing "jack rabbit" starts.

Took it out on pavement and tried all that, as well as zig zag, "sweeping turns" and changing speed ranges. Turning does not seem to do it, but it did pop once after shifting to high range and taking off in forward. But not again or after shifting ranges again.

I don't know if trying to lift the rear wheels, with the BH, and using power will tell me anything, but I did that and manually rotated the rear wheels in both directions. Did not notice anything obvious.

 

[joea]

Lift the front wheels off the ground, have 4wd disengaged and turn, listen, and feel.

Rear wheels?

 

[Edke6bnl]

check lug nuts

 

[North Idaho Wolfman]

It does it in 2WD. I just tested that. Leaves out the front propeller shaft entirely. I'm now thinking it must be the rear axle or differential.

Cannot make it do it "on demand", such as coming to a full stop, reversing, and going forward again, or doing "jack rabbit" starts.

Took it out on pavement and tried all that, as well as zig zag, "sweeping turns" and changing speed ranges. Turning does not seem to do it, but it did pop once after shifting to high range and taking off in forward. But not again or after shifting ranges again.

I don't know if trying to lift the rear wheels, with the BH, and using power will tell me anything, but I did that and manually rotated the rear wheels in both directions. Did not notice anything obvious.

No not really, as the whole Fwd system still turns when it's in 2wd.

And yes check lug nuts!

 

[joea]

This may be just stupid operator. The backhoe swing cylinders are leaking and I plan to rebuild them this summer. Decided to transplant a couple of pines and the must be leaking worse now as when I checked the hydraulic fluid level it was well below add.

So I topped it up and seem better now. I should have looked at that first thing, but, age takes its toll.

 

[KUBB21]

Joea, (or anyone)
I am just jumping in here with a very similar issue on my B21. Did you find your issue yet by any chance? Mine does it.. only in reverse, only in 2wd, only occasional, not repeatable unless I go forward a few feet after it happens and resume the same path in reverse and it will happen again. It is a small jump and loud creek usually only under load up a grade with a slight twist. Are there keyways in the rear axle anywhere? I took a bore scope into the diff housing and all looks good from what I can see that way. I also spun the drive line while the machine was elevated. No issue found. It sure feels like a gear tooth skip when it happens but not regularly in a path of operation. Once it creeks and jumps, it seems good for the rest of that path of travel and also may not happen again for several forward / reverse cycles. Axle flange or something...I have to dig in a little, maybe pull a rear tire for a start. Thanks for any input.

 

[joea]

Joea, (or anyone)
I am just jumping in here with a very similar issue on my B21. Did you find your issue yet by any chance? Mine does it.. only in reverse, only in 2wd, only occasional, not repeatable unless I go forward a few feet after it happens and resume the same path in reverse and it will happen again. It is a small jump and loud creek usually only under load up a grade with a slight twist. Are there keyways in the rear axle anywhere? I took a bore scope into the diff housing and all looks good from what I can see that way. I also spun the drive line while the machine was elevated. No issue found. It sure feels like a gear tooth skip when it happens but not regularly in a path of operation. Once it creeks and jumps, it seems good for the rest of that path of travel and also may not happen again for several forward / reverse cycles. Axle flange or something...I have to dig in a little, maybe pull a rear tire for a start. Thanks for any input.

No, never resolved. Still seems to happen occasionally. I'll look into it again this spring.