[MartyK]

I have a 23HP Z-Force 60" zero turn mower. While mowing the blades disengaged and it seemed the clutch was shot. After replacing the clutch with a brand new one I mowed for about 30 minutes, heard a noise and the blades stopped. The new clutch was laying behind the mower smoking hot with the 4" bolt that holds the clutch in place sheared off laying next to the clutch. A friend looked at it and said its probably a seized bearing in the mower deck.

Has anyone experienced an issue like this? Can anyone offer advice on how to fix, troubleshoot, etc?

 

[MartyK]

Also it seemed the mower deck was vibrating more than usual and the belts were also visibly shaking/vibrating in a strange way. The first clutch looked like the pulley was bent towards the deck, The second clutch came apart and the pulley is what was laying in the yard with the top portion still attached to the mower.

 

[dave_r]

Did that bolt break off flush with the crankshaft or is there enough threads sticking out to grab with visegrips to unscrew?
Was the pto a slide fit on the crankshaft or could it wobble a bit?
Did you replace the belt and/or parts of the deck prior to the original pto clutch failing? Perhaps the belt path is wrong or something is installed incorrectly, putting too much tension on the belt?

 

[MartyK]

It broke off flush and will have to be drilled out.
It's a slide fit I believe.
Yes the center spindle assembly was cracked at the bolts and was replaced. previous Cub Cadet part # is 618-04394 was replaced with new part #918-04426 and was purchased at the Cub Cadet dealership. It seems to spin freely. The belt bath is exactly as shown in the manual and parts list. Something is causing it to freeze up enough to burn/rip through the 3" bolt holding the clutch in place and breaking the clutch into two pieces. Could the spindle assembly be defective?

 

[dave_r]

If the new spindle spins, has the pulley inline with the other pulleys and the pulley is the same diameter, it's not the problem.

It's possible there was a missing washer/spacer on the pto assembly, as you saying the bolt broke off flush with the pto shaft, and the remains of the bolt in your hand only shows a thread or two which is a little too close to running out of threads for my liking...

I don't know why the new pto clutch failed, perhaps it wasn't assembled right, perhaps the bolt wasn't torqued right, perhaps the bolt just decided to fail, perhaps something else.

Going forward, I would suggest
-putting on a new pto with a new bolt the correct length, and with the right spaces/washers
-torque the bolt down
-with the belt still off, spin each of the spindles to make sure they rotate easily, and check that the blades are installed properly and not bent/damaged (as you mentioned the deck was vibrating more than usual)
-put on the belt and feel the tension to make sure it's not too tight, check that the belt isn't rubbing on anything, and manually pull the belt to make sure it moves (this won't be easy, as there is a brake in the pto clutch that means you need to put in some effort to do it)
-start up the engine, and have someone sit on the tractor and (over clean pavement to minimize blowing debris) turn on the pto while you watch how everything spins from a safe distance off to the side, to see how everything works and if anything is wobbling.