John Deere STX38 Shredding Belt to Mower Deck

Hello.

I just bought a used JD STX38 (yellow deck) and enjoyed mowing about 1/4 acre of easy grass and then when I went into some taller stuff the mower suddenly stopped spinning. I looked at the deck and saw the remains of the shredded belt that connects the PTO to the Mower Deck.

I figured the old one was worn out so I got a new belt from the JD dealership ($20) and put it on (this is not as fun as on newer JD riding mowers either). The engine stopped here and there through some easy stuff again, but when I got to some taller grass (where it had to work a little), it shredded the new belt! It is a fun mower to drive--turns easy and has a great chute that blows the grass behind instead of directly to the side, so I'd like to fix it. Also, it fits between the wheel wells of a Ford Ranger.

Before I start replacing random tensioners and stuff, I was wondering if anyone on this forum might have some ideas.

Is this a common occurrence? Is the tensioner spring too tight (the spring was not the easiest to put on--had to pull it a couple inches)? I saw a post on the internet about some kind of design flaw with a spacer on the deck somewhere--anyone heard of any "TSB"s with this mower.

 

Check for bad idler pulleys, belt mis-alignment, deck tilted too far down in the front, or any places where the belt is rubbing another part.

 

Thanks! The deck does appear to be too far down in the front (obviously not level at least). You think this will cause shredding of a new belt? The fix sounds too easy to be true.

 

I've got an owners manual for this unit if you need it. PM and I can send it to you.

 

The front can be down just a little, but it shouldn't be more than a half inch or so. A heavy tilt to the front puts the pulleys at too much angle in relation to the belt coming from the engine. Usually this causes the belt to jump off a lot rather than to shred. Overheating the belt can cause it to shred as well.