Busted bellhousing on Kubota B series

   / Busted bellhousing on Kubota B series #1  

jaxs

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I bought a Kubota B series with bad rattle when clutch is used and here's what I found.
100_3149.JPG
Propeller shaft worn in slight taper. I haven't removed pressure plate and clutch disk for a better look but I expect piolet bushing is gone and end of crankshaft where bushing was likly worn to match shaft.
Here's what started it.
100_3151.JPG

Bolt holes busted out of bellhousing.
I realize this isn't interesting as crank no start or click when turning key but I'd love to hear ideas on fixing these as well as any experience others might have had with one or both.
100_3149.JPG
 
   / Busted bellhousing on Kubota B series #3  
That bellhousing looks to be formed steel rather than cast...maybe? If it is steel, cut the busted flange off 1/2" or so above the face to get rid of all the crud and have a new flange cut from 1/2" plate and weld to the housing. If you don't want to do the complete flange, jus t do the bad portion. No, it won't be cheap but probably cheaper than a new one.
As for the shaft sorta the same deal. It looks like there's a bit of shaft that's still good just before the splines to get a good size measurement. Cut it off, drill a small hole into the center of the remaining shaft and get an end machined up and weld it to the end of the shaft. There's no torque on the very end of the shaft.
Another option would be to have the very end of the shaft turned to accept a smaller Id bearing. Bad part about that is it would mean you'd have to disassemble the transmission. How's the OD of the bearing bore in the crank, chewed up as well or not bad?
Second look...those splines don't look very good.
 
   / Busted bellhousing on Kubota B series #4  
What model? Need more than "B" series.
 
   / Busted bellhousing on Kubota B series #5  
Sure looks cast to me, you can see the mold marks at the bottom and some left over dross too.
 
   / Busted bellhousing on Kubota B series #6  
.....you can see the mold marks at the bottom and some left over dross too.
I saw that but looking at the edges of the breaks it doesn't look like a cast break. It also looks like it's been welded before.
 
   / Busted bellhousing on Kubota B series #7  
I bought a Kubota B series with bad rattle when clutch is used and here's what I found.
View attachment 817412 Propeller shaft worn in slight taper. I haven't removed pressure plate and clutch disk for a better look but I expect piolet bushing is gone and end of crankshaft where bushing was likly worn to match shaft.
Here's what started it.
View attachment 817415
Bolt holes busted out of bellhousing.
I realize this isn't interesting as crank no start or click when turning key but I'd love to hear ideas on fixing these as well as any experience others might have had with one or both. View attachment 817412
Good news, it looks like the bell housing is steel, not cast iron. If so this means that new pieces could be easily welded in place. The input shaft though looks like it is trashed. This is because of the worn splines mostly. If it was me I would replace the input shaft. I can't tell from the pictures but if the bell housing can be removed from the bulk of the transmission then fabbing up plates and welding them in place should be fairly easy. Once the pieces fit the bell housing and holes are drilled for bolts the plates and housing can be bolted to the engine and welded in place. You could use material thicker than original so that you have fillet welds on the side away from the engine. This would mean not having any welding done on the engine facing side that need to be ground off. Of course the housing should be veed out about half way to get some penetration but with thicker plate a substantial bead could be built up that would be stronger than the housing material. Don't let it get too hot when welding because you don't want it to shrink too much when cooling. You might as well put in a new clutch too, at least the friction disc, because the spline in the friction disc will be bad too.
Eric
 
   / Busted bellhousing on Kubota B series
  • Thread Starter
#8  
It is cast iron and yes those are a couple short nickel welds so someone tried fixing in the past, ,very wel might have caused additional cracking. Pre and post heat is a last resort due to size of housing and additional disassembly required. Housing is 10 gauge,as a % , how do you think brazing compares in strength to welding?
I will get pressure plate off and pic where pilot bushing is/was. It has took me a week getting to this point because I can only work an hour or two in the am before heat brings me to my knees. Thanks for the comments and thoughts ,keepum coming.
 
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   / Busted bellhousing on Kubota B series #9  
I've owned 12 Kubota's now and none of them had cast steel bellhousings. All were CI.
 
   / Busted bellhousing on Kubota B series #10  
It is cast iron and yes those are a couple short nickel welds so someone tried fixing in the past, ,very wel might have caused additional cracking. Pre and post heat is a last resort due to size of housing and additional disassembly required. Housing is 10 gauge,as a % , how do you think brazing compares in strength to welding?
I will get pressure plate off and pic where pilot bushing is/was. It has took me a week getting to this point because I can only work an hour or two in the am before heat brings me to my knees. Thanks for the comments and thoughts ,keepum coming.
Grey cast iron has a yield strength of anywhere between 9500 and 60,900 PSI. Brass is 18,000 to 45,000. Silicon bronze is 15,000 to 60,200. 655 silicon bronze is a common alloy and it has the 60,200 yield strength. This is not the ultimate strength but you really don't care about that, you care about when the part starts to yield, whether it is the original cast iron or the weld repair. Mild steel is about 60,000 PSI yield strength. If all you have is an oxy-acetylene torch then I would choose silicon bronze rod or regular brazing rod. There are cast iron stick welding rods that work well too. Stoody Castweld55 is one. It can weld steel to cast iron and do a good job. It will result in a very hard bead though. Suitable for grinding but not machining. No matter which process you use the housing should be preheated to at least 400 degrees. After welding or brazing the area should be covered with some sort of heat resistant insulation to let it cool slowly. I have used the Stoody rod, which is available at almost any good country hardware store, for several jobs and it has never failed. I even welded a Bush Hog gearbox to the frame of the Bush Hog after it started to break the frame. The frame was cracked about 320 degrees out of the 360 degrees. The weld still is holding after about 20 years. It was an emergency repair that was only supposed to last about 4 hours. No matter what you can, and should, use steel plate for the repair pieces. Don't bother trying to find cast iron pieces to fit into the spaces unless you have the original pieces. Besides replacing the input shaft you should replace the pilot bushing too. If the input shaft is not available then it should be machined back to round and then bushed with a hardened bushing back to size. The bushing should be a press fit or a shrink fit. A drill bushing could be used. Any decent machine shop will know what I am talking about. It could also be built up with weld and machined to size. But this will warp the end some so the original center in the shaft, if it has one, will no longer be in the center. A good machinist will know how to remedy this situation. I think that welding and machining or grinding to size, if the center needs to be reestablished, will be more expensive than machining for a drill bushing and buying the bushing. McMaster-Carr sells drill bushings and for the size you would need the cost would be less that 20 bucks plus shipping.
Good luck,
Eric
 
 
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