DRIVESHAFT QUESTION

[wh cc guy]

I have two driveshafts from two different 682 cubs. They both have the same problem that I can't figure out how it could of happened. Both are worn on the side of the shaft that plugs into the rear bushing. Doesn't seem like anything could make them wear that way.
Looking for a expert on these tractors that can explain how or why this can happen.

 

[digger]

I have two driveshafts from two different 682 cubs. They both have the same problem that I can't figure out how it could of happened. Both are worn on the side of the shaft that plugs into the rear bushing. Doesn't seem like anything could make them wear that way.
Looking for a expert on these tractors that can explain how or why this can happen.

The self aligning ball bushings are bad.

 

[wh cc guy]

I have those and they are good. The diameter of the bushings are still round and fit the round part of the driveshaft. Even if the bushing are bad how can it only wear a flat spot on the shaft?

 

[digger]

I have those and they are good. The diameter of the bushings are still round and fit the round part of the driveshaft. Even if the bushing are bad how can it only wear a flat spot on the shaft?

To be honest, I have no clue. It is odd. Do they have cast iron or aluminum rear ends?

 

[mfrade]

I'd think the driveshaft has a bend or twist in it causing a vibration or wobble at speed (WOT).
Also check that the fasteners that hold the transaxle are secure / tight.
As well as the engine, make sure the mounting bolts are tight / secure.

 

[mgonitzke]

I will speculate that either the spherical bushing was run worn out a long time ago and replaced before you got the tractor, or the engine and trans are not aligned properly, in addition to what Mike said.

 

[wh cc guy]

Both tractors have aluminum rear ends. The shafts looked to be running with no wobble while in the tractor. One of the shafts worn spots has straight wall almost like it was machined in it. Does new one have flat spots on them.
Both shafts have more than half of the diameter still good and will fit in the bushing and locate as it should. I have new flex pads ordered from Charlie and trying to decide if I need to repair shafts.

 

[Oak]

Throw them in the trash and order a new 5/8 shaft from McMaster/Carr. They are not worth repairing for what a new shaft cost.

 

[bpientka]

I would also suggest checking all parts of the driveline for wear.

 

[digger]

Both tractors have aluminum rear ends. The shafts looked to be running with no wobble while in the tractor. One of the shafts worn spots has straight wall almost like it was machined in it. Does new one have flat spots on them.
Both shafts have more than half of the diameter still good and will fit in the bushing and locate as it should. I have new flex pads ordered from Charlie and trying to decide if I need to repair shafts.

 

[mfrade]

I'll second what "Oak"says.. if you are already replacing other parts. Put in a brand new shaft also and remove doubt that the old shaft could hurt the new parts.

 

[wh cc guy]

I think I have figured out how this can happen. I stated it was at the rear but it was at the front where it hooks to the engine. At some time someone installed the drive shaft without the self aligning bushing being installed in the retainer that bolts to the flywheel. Without that bearing being there the driveshaft can deflect the flex couplings enough to hit the retainer as centrifugal forces slings it out. Because the shaft doesn't rotate in the bushing it hits the retainer in the same place wearing a flat spot on the drive shaft. The notch in the shaft is the same width as the thickness of the retainer where the bearing is mounted.
Don't know how much forces you get when the drive shaft wobbles but after a while it does wear into the soft driveshaft.

This is some old parts I had laying around that shows how this happens. At least I think it happens that way. Thanks for the replies.

 

[agitch]

Since you have it out, I would get a new one as well and you'll have a good drivetrain for several years.

 

[wh cc guy]

Repaired the shaft and replaced flex disk and bearings from Digger. Everything seems to be working ok as for as the drivetrain is concerned. Thanks for the replies.