62 Inch MMM Constantly Breaking Belts - New Pulleys?

[The Suburban Farmer]

I have a 62" mid-mount mower on my Deere 2320 has been bullet-proof for the last few years. However, the original belt FINALLY broke after 7 years. I replaced the belt with an OEM belt, but now it's breaking belts every ~2 hours. Specifically, the belts appear to be wearing on the bottom of the belt first, then shredding rather than a clean break. When the belt is new, the cut quality is excellent with no odd sounds or vibrations that I can detect.

So far, I've:

• Removed and cleaned the deck and checked for debris
• Removed and balanced the blades
• Checked for overall deck level
• Checked the spindles and bearings (they seem to spin freely with no wobble or grinding)
• Checked all the pulleys for burrs or knicks
• Measured the pulley height against the main drive pulley to ensure they are all consistent.

I have to admit - I'm now stumped. After all the above, it looks like a brand-new deck - but it's still shredding belts.

I'm thinking of taking off all the pulleys and turning them on my lathe to see if they are out-of-round and maybe trying to refile the edges of the pulleys with a fine file in case there are any burrs I may have missed. Does that seem like overkill, or am I missing something simple that I should try before turning the pulleys on the lathe?

I've busted $250 worth of belts in the last couple of months and this is getting expensive! Any thoughts or recommendations would be greatly appreciated.

 

[alexpops]

Any indications on one of the pullies of excess wear? How is the idler? Perpendicular to deck, or angled so the bottom of belt is being driven towards deck? Spring tension on idler ok (no slippage when you hold blade & try to move belt)? How about the main gear box alignment? I had a sears mower deck where the casting ears would crack on the spindles & it was enough to tilt the pullies when under load, but seemed ok on a casual glance over. same belt shredding after heat & burnt rubber smell. Grease nipples or sealed bearings?

 

[alexpops]

Final thought ... any marks on the shrouding that belt(s) are coming in contact with the metal belt covers?

 

[KennyG]

If you see wear on an edge, either one of the pulleys is out of line or there is something sticking up on the deck rubbing the belt. Since this is a shaft drive deck, all the pulleys should be in exact alignment. I broke my first belt after about 5 years but I think it was because I let too much junk build up under the deck drive over ramps. The second belt looks fine after over 7 years. Other than taking the ramps and shields off and very carefully checking the alignment and clearances, I can't come up with any other ideas. If you can't find anything, I would go ahead and talk to the dealer.

 

[oldnslo]

If like my X540 deck there are two or three hold down clamps that bolt over the belt. If one of these is slightly out of position the belt will rub. Also one or two guides that bolt on idler that can be installed incorrectly and rub on the belt.

 

[KennyG]

If like my X540 deck there are two or three hold down clamps that bolt over the belt. If one of these is slightly out of position the belt will rub. Also one or two guides that bolt on idler that can be installed incorrectly and rub on the belt.

Probably not the issue here. The 62 deck, being a shaft drive, has no guides or retainers. The belt runs exactly in a single plane held on by single spring loaded tensioner.

 

[Williy]

Little some thing for you to read:
I prefer the belt to be inside the pulley just barely not sticking out
and I lost too many belts the did not fit inside the groves

This is Why Your Belt Keeps Falling Off Your Lawn Mower

If you own a lawn mower, chances are you have had a belt come off your mower and wondered why. If you have a belt that won’t stay on your …

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willy

 

[mini14]

Change all your pulleys

 

[The Suburban Farmer]

Thanks again for all the suggestions. Just to close the loop here, it ended up being caused by a crack in the deck underneath the pulley tension bar. When I took the tension spring / swing arm assembly off the deck, I saw that the deck was cracked underneath. As a result, the deck was structurally flexible enough so that the spring tension would pull the entire assembly out of square when under tension. Not sure how it cracked since nothing else was damaged and I don't recall hitting anything, but some welding and grinding and all is now good. I was surprised at how badly it was cracked. You can also see where the idler pulley rubbed off the paint as a result of being pulled out of alignment.

Hard to see in the pic, but I tried to put arrows where the major cracks were. I used a Dremel with a diamond tip to open up the cracks, and then welded from both sides. As extra insurance, I also put a large washer on both sides of the deck to help spread the load a bit. Seems to be working good-as-new now.

 

[WranglerX]

Cracking of this sort is usually caused by fatigue and not by hitting something..... If its cracking the structural design is to weak to maintain the forces needed to keep tensioner operating properly....