L35 4 wheel drive stopped working

[breenfarmer77]

I have (my landowner actually) a Kubota L35 tractor. Not sure of the year but is fairly well used and was purchased used by the landowner. Most of the existing equipment on the farm have NOT been maintained very well and I find myself spending plenty time doing repairs that may have been prevented through routine maintenance. I operate a small homestead farm where I take combat veterans and teach homesteading skills as a therapy and a reason to want to wake up every day. A few days ago one of my interns was transferring manure into an existing compost pile and noticed that he was getting stuck plenty even though he was in 4 wheel drive. I initially thought he was slipping on wet manure but upon trying the tractor out myself I was instantly stuck and noticed that the front wheels were not moving. Crawling under the tractor I found that the driveshaft (others on this site are using the term "propeller") coming from the transfer case into the front axle has a tube like housing surrounding the shaft and there is a complete tear of the metal tube about 2 inches from where the shaft goes into the front axle. There is an O-ring at the end of the tube which has come out of the axle (actually from the exploded view I found on google it is called a front axle bracket). I will lift the front end using the bucket later this evening when outside temps cool off but I suspect that I will find that the front wheels will turn independently of each other...I have already read a thread which says that they will move opposite of each other if the front axle is working correctly (or that they won't move at all...if I understood correctly). I'm not much of a mechanic and am hoping beyond hope that this is some sort of shear pin failure and not a complete differential gear failure or that it is something major in the transfer case. I work well with photos but another thread touching on a similar issue promised photos but, alas, none seemed to be posted. I could use some direction as to where to start. Thanks much.

 

[1970cs]

Is that tear on the tube longitudinal or horizontal? If it's horizontal given that position you spoke of, my guess would be the roll pin walked out or broke in the front coupler.

You need to collapse the outer shield enough to expose both couplers and try to see if that the front coupler has walked back far enough to become disengaged from the pinion shaft splines. I have seen worn splines on couplers before also.

 

[breenfarmer77]

The tear is circumferential around the cover of the propeller about 2 inches from where the whole thing enters the front axle. I'm getting the tractor up on blocks today after chores are complete and will post a few pics. I'm hoping that it's a mere roll pin...sounds like a much easier fix than I could hope for.

 

[rentthis]

What 1970cs described is common and absolutely the first thing to check.

 

[breenfarmer77]

I think you are accurate about the coupling having possibly walked back as the sheath covering the driveshaft (propeller shaft) seems to be sliced about where the pin is. The pin is still partially in the hole but I can feel the far end of it on the back side of the shaft and it feels rough as though it slipped partially out and wrecked itself while spinning. My only concern is that the roll pin is still partially inserted and only appears to be about 1/4" out of place which makes it hard to imagine how the shaft has walked back as was suggested. Photos should be being uploaded as I type.

 

[breenfarmer77]

Spline and coupling. I could slide the sheath back a bit by loosening the hose clamps that held the rubber coupler.

 

[breenfarmer77]

Ok...just sitting inside the kitchen thinking about the logics of this. I am imagining that the pin started coming out and wore the inside of the protective sheath until it finally sliced through it. I didn't capture a photo but there is also a hole torn through the sheath which seems to match the diameter of the roll pin and seems likely that it was either the result of the initial episode of the roll pin coming out of the hole, catching and puncturing the sheath and then was ongoingly wearing the inside down until it totally sliced the sheath open. Or the other way around. It just seems strange that I can see the roll pin still in the hole but that the coupling doesn't actually operate. I think the pin must be sheared inside the hole and not allowing the coupling to operate. I'll be punching it out soon to see what it looks like. Thanks for above comments and any other insight. Wondering how hard it is to remove the front axle rear bracket so that I can slide a new sheath over the shaft and ensure dust, dirt and water don't get inside and mess with the bearings or gears.

 

[breenfarmer77]

I was able to collapse the sheath and removed the roll pin. It was not fully intact and looked like it had partially slid out of the hole and likely did cause the wear that sliced open the sheath circumferentially. When I slid the coupler towards the rear of the tractor on the driveshaft I noted that there was quite a bit of wear on the splines of the spiral bevel pinion shaft. According to the local dealer parts guy the wear is due to a lack of grease having NOT been applied via the zerk fitting which is located directly above the front axle where it connects to the tractor. He said that over time this caused it to be out of alignment causing the wear on the splines. If he's accurate (this was accomplished over the phone with me under the tractor describing it) then this is a much bigger job and far more expensive than I had anticipated. Does anyone have any other insight that I may explore before succumbing to this potentially major job?

 

[Fedup]

What you see is far more common than you might think. If I were on the phone with you discussing this problem(as was your dealer's shop tech) I would be telling you the same thing. Tractors with solid splined drive(propeller) shafts need to be in relatively perfect alignment front to rear, or such spline/coupler wear will happen. I presume you have a loader on the tractor? The added weight compounds the the effect on the pivot bushings and related wear surfaces.. I have repaired/replaced a number of pivots/bushings over the years, most due to lack of grease.
A tidbit for you, once you get the problem corrected. Grease both front and rear bushings as you normally would. Then, using the loader, raise the front axle off the ground, and grease both again. I think you will find that with the first greasing you will see grease exit from the top of the bushings. The second time you should see grease on the bottom side of each bushing. If the grease passages are functioning properly(and they should be after your repair) this technique assures the bushings are lubricated all around. After all, the bulk of the contact/wear is on the bottom of both pivot and bushing. This area gets very little grease with the weight of the tractor reducing the space.

 

[1970cs]

Sounds like it's time for pivot bushings (hopefullly) also check the pivot surfaces on the axle for wear and it also sounds like a pinion shaft is in order?

Pat

 

[breenfarmer77]

I've put this on the back burner for a bit as I've got so much more to accomplish on my farm than I could stay ahead of. I very much appreciate all the input and direction. I've been running it in 2 wheel drive minimally but will be needing 4 wheel as winter is coming rapidly here. What would you expect a shop to charge for the pivot bushing repair? Also the pinion shaft? Would these be relatively easy to accomplish if I can borrow my neighbor's shop to lift the front end and expose the necessary work? I'm not a mechanic but one tends to learn things quite quickly when one is financially compelled. Once again, I very much appreciate those of you who took time to help me with troubleshooting this. Now back to repairing a Nikki carb for my landlady's riding lawn mower.