Kubota B7200D Bad Clutch- Need advise on Changing it out.

[metricquartz]

I will contact a few machine shops in my area and see what they have to say about this and decide a plan of action based on that and also costs involved. Tearing down the engine to get at the crankshaft doesn't sound like something I want to do to this thing, If I was the original owner and I truly had a long history with it then things would be different. Thanks for all the great information.

 

[TheOldHokie]

I will contact a few machine shops in my area and see what they have to say about this and decide a plan of action based on that and also costs involved. Tearing down the engine to get at the crankshaft doesn't sound like something I want to do to this thing, If I was the original owner and I truly had a long history with it then things would be different. Thanks for all the great information.

Tough to rebore the end of the crankshaft without taking it out of the engine. Not impossible but assuming you can find a shop willing to undertake it it will cost you some cash.

I misunderstood your initial description of the proposed repair and thought you were putting the ball bearing in the end of the crankshaft which you were going to rebore. Now that I see you were putting it in the flywheel I don't see any issue with doing that. Plenty of engines do it that way. What is the OD of the seal area on the propeller shaft and how thick is the center of the flywheel?

Dan

 

[metricquartz]

The center hole in the flywheel measures at about 0.804 and the propeller shaft area where it exits the clutch disc is 0.490-0.580. The bearing that
TheOldHokie
recommended to me ( 60002RS ) I looked it up and he was correct that it is a better choice than what I said (3/8x7/8 std.) as it would allow me to keep as much material as possible. The thing I need to watch out for when having the flywheel turned is the mounting bolt location and getting to close to them, That is why I originally thought of using only one bearing so that it did not need to be cut all the way through. I am in the Chicago-land area and I looked it up and within 10 miles from me there are over 100 machine shops so I hope I can find someone that wants to take on this job of mine without becoming rich.

 

[kubotafreak]

Ditch the machining job, buy a new shaft for the hundred dollars and scab up the bushing/seal with jb weld. I think your going to need to find out what really caused this in the first place. I find it hard to believe it was only a dry bushing. I suspect that input shaft bearing on the trans side.

 

[TheOldHokie]

The center hole in the flywheel measures at about 0.804 and the propeller shaft area where it exits the clutch disc is 0.490-0.580. The bearing that
TheOldHokie
recommended to me ( 60002RS ) I looked it up and he was correct that it is a better choice than what I said (3/8x7/8 std.) as it would allow me to keep as much material as possible. The thing I need to watch out for when having the flywheel turned is the mounting bolt location and getting to close to them, That is why I originally thought of using only one bearing so that it did not need to be cut all the way through. I am in the Chicago-land area and I looked it up and within 10 miles from me there are over 100 machine shops so I hope I can find someone that wants to take on this job of mine without becoming rich.

If you were near me I would do it for the fun of it.

A 6000-2RS bearing is 10mm x 25mm x 8mm. If there is 25mm of space between the opposite bolt holes you have nothing to worry about. What is of more concern is the diameter of the propeller shaft where it will go through the bearing. It will need to be turned down to 10mm (.3937) for a close free fit.

Dan

 

[TheOldHokie]

Ditch the machining job, buy a new shaft for the hundred dollars and scab up the bushing/seal with jb weld. I think your going to need to find out what really caused this in the first place. I find it hard to believe it was only a dry bushing. I suspect that input shaft bearing on the trans side.

The culprit is more likely the flexible joint on the transmission end of the propeller shaft. Its what failed on mine and inflicted similar but less catastrophic damage. Had the noise it was making been ignored it could easily have progressed this far.

Dan

 

[kubotafreak]

The culprit is more likely the flexible joint on the transmission end of the propeller shaft. Its what failed on mine and inflicted similar but less catastrophic damage. Had the noise it was making been ignored it could easily have progressed this far.

Dan

Couldn't agree more.

 

[metricquartz]

I will look at that input shaft bearing on the trans side before I order my Kubota parts. I neglected to say that the fork also bit the dust.
Dan, Thanks for your offer, I wish I was closer and take you up on your offer. There is 25mm distance as the bolt holes are offset.
I think that putting a good bearing into the flywheel and turning down the shaft would be a better and longer lasting repair rather than epoxying a thin Kubota bearing in a huge hole.

 

[North Idaho Wolfman]

You can bore the crank right in the engine, using the engine as the drive, and using a boring bar.

 

[TheOldHokie]

I will look at that input shaft bearing on the trans side before I order my Kubota parts. I neglected to say that the fork also bit the dust.
Dan, Thanks for your offer, I wish I was closer and take you up on your offer. There is 25mm distance as the bolt holes are offset.
I think that putting a good bearing into the flywheel and turning down the shaft would be a better and longer lasting repair rather than epoxying a thin Kubota bearing in a huge hole.

I agree - I am not a proponent of JB Weld or its friends. But then I have a reasonably well equipped machine shop when situations like this arise.

It is not a difficult repair and one that machine shops see all of the time. Do you know what the OEM diameter of the propeller shaft is where it goes through the outer seal? I would feel much better about using a new shaft and matching that diameter. You are not going to save any money if you have to pay someone to turn the old one down. And as I said in response to Kubotafreak, your problem was probably caused by the flexible coupler on the transmission end of that shaft. They wear out and take the other end out as well.

Dan

 

[TheOldHokie]

You can bore the crank right in the engine, using the engine as the drive, and using a boring bar.

If you have a boring bar why use the engine as the drive?

Dan

 

[kubotafreak]

If machining, I figure you would just use a small indexable fly cutter with the engine sitting on the crank pulley. In a Mill. I would still do my prior. The bushing is a press fit even with the missing section. The jb is only needed as a filler, not as adhesive. Jb has some impressive compressive strength. That shaft is cheap. Not even worth rework, especially for $100. That bearing assembly, and input seals are pricy though. Dunno if anyone else has tried but jb weld machines well, very smooth. Your engine, money, and pillow. I fix this stuff all the time. Thats why own my own machining equip. Couldnt chuck that size engine though, but still not rocket science.

 

[PoTreeBoy]

I'm going to throw this out for you guys to laugh at. Have a shop make you a drill/ream guide that would center on the flywheel holes. Bolt it to the crankshaft flange then drill or ream the crankshaft to fit a bushing or bearing.
It wouldn't be as accurate as a mill or lathe, but it'd be easier and better than what you had.

 

[TheOldHokie]

I figure you would just use a small indexable fly cutter with the engine sitting on the crank pulley. In a Mill.

Not rocket science for sure. Hard to tell from the picture but you are probably right about the pilot bushing - looks like it is mostly there and the hogged out area can probably just be ignored. I am a fan of anaerobic sleeve retainers for insurance on those repairs.

I do a lot of these repairs as well. In the top picture that's what I call an indexable face milling cutter (aka fly cutter) in the spindle. If I were going to bore the crank my setup would be a boring head (bottom picture) in the horizontal spindle with the engine bolted flat to the table. To bore and sleeve the flywheel I would use the vertical spindle and the same boring head. In the second picture that hogged out axle housing repair was the the same repair I would recommend for the flywheel. The press fit sleeve for it was turned from some thick wall 1020 steel tube.

Dan

 

[metricquartz]

I am not sure of the OEM propeller shaft dimensions, It must be somewhere around 0.557 as that is what the ID of the new Kubota bushing measures that I had purchased thinking that would be the easy part.
The flexible coupler on the transmission end of that shaft is still attached to the propeller shaft as of now, It won't come off as I have tried to, but it is possibly frozen on in which case I will heat it up a bit to persuade it to come loose or it is retained somehow..
I am not against buying a new shaft but until I find out what avenue I will take, Either the Flywheel or Crank method.
If the flywheel is the better approach then it makes no sense to buy a new shaft as it would need to be turned down anyways to use a bearing or two into the flywheel so that I can use the 26mm OD to fit in between the mounting bolts.

 

[TheOldHokie]

I am not sure of the OEM propeller shaft dimensions, It must be somewhere around 0.557 as that is what the ID of the new Kubota bushing measures that I had purchased thinking that would be the easy part.
The flexible coupler on the transmission end of that shaft is still attached to the propeller shaft as of now, It won't come off as I have tried to, but it is possibly frozen on in which case I will heat it up a bit to persuade it to come loose or it is retained somehow..
I am not against buying a new shaft but until I find out what avenue I will take, Either the Flywheel or Crank method.
If the flywheel is the better approach then it makes no sense to buy a new shaft as it would need to be turned down anyways to use a bearing or two into the flywheel so that I can use the 26mm OD to fit in between the mounting bolts.

The coupler is pinned to the transmission input shaft,

This is a Japanese machine and almost everything is metric. I am going to guess the shaft is 14mm (.551). A ball bearing is going to be to large so I would considwer a needle roller bearing. You need a hardened inner ring for the shaft and al I could find was Koyo JR 141717. There are a lot of 17 x 23 mm needle roller bearings that would work with that inner ring.

Dan

 

[metricquartz]

Well if I had machining skills that you guys have and tools it would not feel so daunting to me but I don't and I am sick about this can of worms I opened up.
Hopefully I can find a good machine shop that can handle it. I can turn a wrench but this is way beyond my skillset. Thank you all for your replys. I will let you know how I make out and will include photos.

 

[kubotafreak]

TheOldHokie,

Nice machine! I think we are saying the same thing. You chucked that boring bar in a indexable head to fly cut(Static workpiece, moving cutter). Maybe I should have been more specific. Indexable boring head. I like the small indexable heads that are smaller than the workpiece hole. They eliminate the chattering with having the bar extended vertically. But with everything this stuff is expensive. Seems like every time you get a cutter you need a new one larger or smaller...

OP,
Just keep in mind we can table talk every option under the sun here. Once you price real world service it isn't cheap. Unless you can get lucky, and find a good buddy. Don't be surprised if most shops want to fix it their way, and not have anyone micro manage the way they repair. Some are very sensitive to this...

 

[TheOldHokie]

TheOldHokie,

Nice machine! I think we are saying the same thing. You chucked that boring bar in a indexable head to fly cut(Static workpiece, moving cutter). Maybe I should have been more specific. Indexable boring head. I like the small indexable heads that are smaller than the workpiece hole. They eliminate the chattering with having the bar extended vertically. But with everything this stuff is expensive. Seems like every time you get a cutter you need a new one larger or smaller...

OP,
Just keep in mind we can table talk every option under the sun here. Once you price real world service it isn't cheap. Unless you can get lucky, and find a good buddy. Don't be surprised if most shops want to fix it their way, and not have anyone micro manage the way they repair. Some are very sensitive to this...

No machinist wants to be told how to do a repair by the customer. Most wont even listen.

Dan

 

[metricquartz]

So what you are saying is that these machine shops are like the soup Nazi on Seinfeld.