JD345 with 54C deck-drive belt burns/twists off

[SAM999990]

I have a JD 345 with a 54C deck. My problem is the drive belt has been popping off sometimes twisted and deformed or just burns off. It appears my drive belt is rubbing against the cap over the tension idler sheave pivot shaft which is really close to the drive belt. The rubber cap eventually burns off or falls off and then it is rubber belt on metal shaft causing the belt to burn and break or it pops off before it burns through. I believe I have checked all the belts and pulleys and made sure everything was tight. I have the service manual for my 345 and the schematics and assembly parts of the deck. I am stumped as to why the belt is so close to this pivot shaft. Is there a spacer that raises the the jack sheave pulley so that the belt is just above the top of this shaft cap? Does anyone have any ideas?

 

[beenthere]

:welcome: to the forum.

Puzzling problem, but for sure the belt should not be rubbing on anything.

Did this deck come to you new and on the 345? Is it a JD belt?

 

[SAM999990]

Deck came with 345 - I bought it new in 2002 from JD dealer.

I thought I had it figured out yesterday before my post. Everything was tight. Clearance between drive belt and adjacent pivot bolt looked like about 3/8" maybe as much as 1/2". I did not measure. I ran the tractor yesterday and cut approximately 1/4 to 1/3 of an acre. Was working fine before drive belt burned off. No vibration noticed although I suspected something might be wrong just seconds before it broke. I did not smell rubber burning - break was quick which might suggest jack sheave shifted allowing belt to jump into adjacent tension idler sheave arm pivot bolt assembly.

I believe it has something to do with the jack sheave. I am going to try to look at it again later today.

This deck was originally sold with the GX345. When I bought mine, I beleive I was inquiring about bagging attachment (thinking into the future) so they included a 54C deck with my purchase. The 345 was listed supplied with up to a 48C and only a regular 54 deck. The service manual for the GX345 lists all the schematics (very clear) of the 54C deck. The 345 manual, only the 54 (not as clear).

The machine has been great for us. Every couple of years the deck needs some service (blades, belts, minor) as we have about 3-1/2 acres to cut.

If you have a 54C, can you measure the clearances and distances around the jack sheave pulleys for me and the springs behind the jack sheave pulley.

Might help.

PS
Belt is JD - always JD parts
also can you measure clearance between drive belt and adjacent pivot bolt cap and whether belt is directly next to this cap along same horiz. plane or if the belt sits a bit higher to avoid any horizontal contact.
thanks in advance for any help.
sam

 

[beenthere]

Sam
I realized after going out to look at mine, that ours are different as I have the PTO drive shaft (so no drive belt). I will be able to look closer at mine, but don't think I can be of much help with the sheaves.
If you can find some errant movement in yours, it might be the culprit. Did it burn off the plastic cap again, or have you not been replacing that? Maybe fashion something over that (like a teflon block) that would protect the belt when it rubs.

 

[SAM999990]

I think its some errant movement around that jack sheave. I will probably kick myself when I find what it is. I have replaced the plastic cap once but I won't replace it again until I find out the main cause. I appreciate your input and ideas. I will keep plugging away. Teflon block may be an option but if I do not find the problem, introducing something else into the equation may provide add added stress to the belt if it is moving or vibrating when the problem occurs.

 

[SteveInPA]

I think its some errant movement around that jack sheave. I will probably kick myself when I find what it is. I have replaced the plastic cap once but I won't replace it again until I find out the main cause. I appreciate your input and ideas. I will keep plugging away. Teflon block may be an option but if I do not find the problem, introducing something else into the equation may provide add added stress to the belt if it is moving or vibrating when the problem occurs.

So I'm having the same problem you described, with my GT235 and 54C deck. Did you ever figure out what the cause was? I've been using this same tractor and deck for 11 years and this never happened before. It seems to have come on suddenly as I was finishing up mowing about 1.5 acres. Now I can't prevent the same rubbing/twisting and burning of the drive belt. I tried adjusting the level front to back and side to side, but can't seem to stay in spec without it rubbing. Let me know if you figured it out. Thanks!