Crank and propeller shaft replacement B6100!

[B6000ME]

I split my newly purchased b6100 in half to do a clutch. I also purchased a new pilot bearing as I figured it would be good to replace it while I was in there. Unfortunately both of my propeller shaft and the inside of my crankshaft where the pilot bearing goes are completely worn out. It appears I will be purchasing a new propeller shaft and either having this crank machined or possibly replacing the crank! Thae rear main seal is also wiped, to add insult to injury someone else had been in here previously and cross-threaded one of the bolts for the flywheel so of course that broke upon removal. The good news is a team of two of us was able to split the tractor in half from running to completely disassembled in less than 48 minutes! Now my hunt for parts begins! Anyone else that has had experience with this issue feel free to chime in.

 

[North Idaho Wolfman]

You'll get a better view of the pilot bushing if you pull the dust seal.

 

[torch]

Like Wolfman said, pull the seal and verify that the crankshaft is actually worn first. It's possible that just the pilot bushing is worn.

That assumes you can get the cross-threaded bolt out cleanly and repair the threads, of course. I would slip a nut over the stub and weld it to the remaining bit of bolt. Not only does that give you something to grip with a wrench, the thermal shock and weld shrinkage may -- MAY -- help.

 

[B6000ME]

The dust seal is removed in this Photograph! The hole is just worn that much! The end of the propeller shaft is worn down almost 1/16 of an inch. I will try to get some better photographs today.

 

[torch]

Wow. Must be the dirt and grease, but I thought that was a seal lip under it all.

For reference, I just did my clutch: The shaft end was 0.547". The pilot bushing ID of a brand new Kubota pilot bushing is 0.558". I'm told (but neglected to measure for myself) that the hole in the crankshaft is 17mm.

 

[B6000ME]

Damage Pics

 

[rentthis]

I'm hoping that bolt broke from something other than cross threading. Maybe using torches removal method will reveal good threads. I got my fingers crossed.

 

[torch]

From the picture, the hole looks round. It might be possible to clean it up with a reamer without disassembling and press in a bushing. What is the diameter now?

Here's a couple of hand reamers that might be suitable:

11/16": https://www.mscdirect.com/product/details/02210441

3/4": https://www.mscdirect.com/product/details/02220481

Once reamed to size, a machine shop could make up a bushing with a very light push fit. Install over red (permanent) locktite and install the Kubota pilot bushing.

 

[North Idaho Wolfman]

Sorry really looked like the seal was still there.

Looking at the pics it looks like someone put the flywheel on wrong and forced the bolts in, there looks to be thread damage on another thread set too, common issue, as the bolt holes are actually spaced different to make the flywheel line up one way.

I would get new bolts, and replace them all, as others are probably stressed.

You could have someone with good machining skills fix the bushing surface in the end of the crank.

Good used cranks are getting harder and harder to find these days.
Just so you know when looking for a crank, there are 2 different style cranks that will fit it, but they take different rear main seal covers.
The cranks are the same for a D650, D750, D850, D950, just note the rear main seal dimension.

 

[B6000ME]

Well after my initial disgust and frustration last night. I took some additional pictures this morning and went to work thinking about the problem. My friend whose garage the tractor is at called me about midday and said he thinks he has a solution, so this evening we set about using his lathe to make a tool to align the new pilot bearing in a bed of epoxy. With careful drilling and just a little bit of heat we were able to get the cross threaded bolt out. ( anyone know the thread pitch off the top of their head so I can buy a tap). Here's a few pictures of what we've done so far, and apparently takes about eight hours for this epoxy to set up! I will not know the results until tomorrow and I still have to order some parts. Hopefully this will end up being a permanent or at least a long lasting repair. Fingers crossed!

 

[B6000ME]

More pictures

 

[B6000ME]

Last batch. We also roughed up the outside of the pilot bearing and scored the inside area of the back of the crank so that it would have some ridges for the epoxy to bite into. We will leave the tool inserted overnight so that it stays directly centered while hardening and hopefully will be good to go and reassembly next week when the parts come in.

 

[torch]

It could work. I've heard of people successfully doing similar with JB weld.

Take one of your old bolts. Measure the diameter, rounding up to the nearest millimeter. Now count 10 threads, measure the distance in mm and divide by 10 to get the pitch (metric thread pitch is mm per thread, the inverse of inch thread pitch measurement).

 

[Russell King]

( anyone know the thread pitch off the top of their head so I can buy a tap).

I suggest you take one of the other bolts with you and have the thread size and pitch measured. You can buy plastic thread gauging tools at most hardware stores if you want to do it yourself but since you will probably be at a bolt shop buying the tap, they can do that for you.

Kubota seems to lean towards the fine and extra fine pitches for the fasteners they use


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[B6000ME]

Finally ready to work........not sure on what yet!