John Deere 345 blade clutch issue

[scollins]

I'm working on a John Deere model 345 with 500 hours on it for our church. The mower has worked flawlessly for years but recently the bolt that holds the blade clutch to the crank shaft broke. Replaced it with new bolt from dealer. Broke again within about an hour of mowing. Replaced with bolt from dealer. Broke after an hour. Replaced with bolt on half inch longer. Broke within five minutes. HELP.

Clutch appears to work properly both on the mower and off.

 

[beenthere]

:welcome:
I'm not understanding the terminology you are using to describe the problem. But hopefully there are others who will be able to figure it out.

Is this the clutch? And is it the bolt shown? And only one bolt holding that clutch?

 

[jinman]

I'm working on a John Deere model 345 with 500 hours on it for our church. The mower has worked flawlessly for years but recently the bolt that holds the blade clutch to the crank shaft broke. Replaced it with new bolt from dealer. Broke again within about an hour of mowing. Replaced with bolt from dealer. Broke after an hour. Replaced with bolt on half inch longer. Broke within five minutes. HELP.

Clutch appears to work properly both on the mower and off.

Welcome to TBN.

I think you are "fixing" the symptom rather than the problem. If the bolt is shearing off, it must be from too much torque to start the mower deck. I would remove the mower deck and closely inspect all spindles and pulleys to look for binding. There might also be something rubbing against the belt that is adding additional force, but normally that would be accompanied with smoke and odor. I'd bet that if/when you get the mower deck "tuned up" the problem will go away.

 

[scollins]

Yes this is the clutch I'm talking about and yes it is the bolt that goes through the assembly and into the crank shaft.

 

[scollins]

:welcome:
I'm not understanding the terminology you are using to describe the problem. But hopefully there are others who will be able to figure it out.

Is this the clutch? And is it the bolt shown? And only one bolt holding that clutch?

Yes this is the clutch and yes that is the bolt.

 

[John_in_TN]

The deck's torque load should be driven by the key (inside the clutch) against the keyway in the motor crankshaft.
Have you checked the condition of the key & keyway?
Is the clutch pulley bent, warped or otherwise damaged?
Are you tightening the new bolts to the specified torque?
Good luck?
John

 

[jinman]

The deck's torque load should be driven by the key (inside the clutch) against the keyway in the motor crankshaft.
Have you checked the condition of the key & keyway?
Is the clutch pulley bent, warped or otherwise damaged?
Are you tightening the new bolts to the specified torque?
Good luck?
John

I think you may be onto something John.:thumbsup: If the key was lost when the clutch first came off or it is a shear type key, it is probably completely missing.

 

[John_in_TN]

I don't think it is a seperate key. The JD clutches I have seen had the key cast into the ID of the clutch assembly.

 

[banjodunn]

G'day i think you are spot on and the bolt is prob trying to take the load rather than a key is the clutch a nice neat fit onto the shaft or is there a bit of movement, may have flogged the centre out of the clutch if this is the case you are never going to keep it tight you may need a new clutch


Jon

 

[tomnky]

I don't think it is a seperate key. The JD clutches I have seen had the key cast into the ID of the clutch assembly.

I have a GT242 and the last clutch that put in required a piece of 1/4" key stock. So it could be that the key is missing.

 

[John_in_TN]

Maybe a lost key does explain the repeated breakage. The JD clutches I have seen (with cast-in keys) were all on LX series, and older similar sized machines. Maybe the heavier GT and 300 series do have seperate keys.

 

[tomnky]

Maybe a lost key does explain the repeated breakage. The JD clutches I have seen (with cast-in keys) were all on LX series, and older similar sized machines. Maybe the heavier GT and 300 series do have seperate keys.

The first two clutches I replaced had the key built into the clutch as You describe, I think they(John Deere) probably changed suppliers.

 

[scollins]

Thanks for all the helpful hints. The bearing inside the clutch pulley was very hard to rotate and there was some play in the clutch itself. The washer on the broken bolt indicated rotation of the washer on the tightened bolt.

I replaced the clutch with a new one and so far so good.

FYI
Both new and old clutch assembly had the key in the clutch so all you have to do is align it with key way in crankshaft when installing. Also, while trying to remove the remaining part of the broken bolt, I broke an easy out extractor in the crankshaft. I was fortunate to enlist the help of a master welder who was able to build up the broken bolt with welding rod and then weld a nut to it. I was amazed at the skill required to perform this "miracle".

Thanks again. This is a great web site.

 

[John_in_TN]

Glad you got it all sorted out, and thanks for letting us know what you found.
I agree: a skilled welder can do amazing things!