Kubota G4200 PTO Belts Rapidly Breaking

DankyYanks

New member

Equipment
Kubota G4200
Aug 16, 2022
3
0
1
Alabama, USA
I recently purchased a fairly good shape Kubota G4200, after repairing some rust holes on the deck, servicing the various fluids and greasing every grease fitting on the mower I attempted to install the new PTO belts I had bought. https://www.amazon.com/gp/product/B08CQ4TZ2T/ref=ox_sc_act_title_1?smid=A1NOZYATA1STC0&psc=1 These are admittedly the cheapest ones I could find but I figured I would give them a chance. The issue I was running into was the belts were wanting to turn even when the PTO was off, so I checked and greased the PTO belt tensioner and it wasn't seized or anything and when in the off position it was letting of the belt. The "brakes" are all still in tact and present. So I loosened the adjuster until they weren't turning when the PTO was off, but then the problem I ran into was the belts were smoking and burning up rapidly when using them. I have the adjuster as loose as it realistically can go and they are still making noise when the PTO is off and when the PTO is on they are smoking badly and burning up, specifically the outer belt, one closest to the front of the mower. The inner belt lasted through 3/4 of an acre before shredding itself. Just really don't know what to do at this point. Here is what the pulleys and everything look like. Oh and yes I know the adjuster is broken, I am going to handle that eventually, honestly I am just asking for advice or the proper way to install these belts. All the pulleys move freely none are seized up, that's why I can't figure out why the belts are shredding themselves up. I also can't afford to pay Kubota's price tag for OEM belts if they are just going to burn up and shred themselves too.
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Torinodan

Active member

Equipment
T1600, G4200, G5200, Ford 2810, 1974 Wheel Horse C100
Oct 14, 2021
199
94
28
Fayetteville GA
Check alignment
Check no sharp edges on idler/ lower pully
No too much play in idler bearings or lever
Not too tight
 
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DankyYanks

New member

Equipment
Kubota G4200
Aug 16, 2022
3
0
1
Alabama, USA
Check alignment
Check no sharp edges on idler/ lower pully
No too much play in idler bearings or lever
Not too tight
I will do that, the lower pulley I noticed has a spot where it is bent inwards towards the outer belt, I am wondering if that caused the lower belt to smoke. But I am not entirely sure.
 

DankyYanks

New member

Equipment
Kubota G4200
Aug 16, 2022
3
0
1
Alabama, USA
I'm wondering if I could get away with just using normal V-Belts. It seemed the teeth on those PTO belts just wore off quickly anyway.
 

BruceP

Well-known member

Equipment
G5200H
Aug 7, 2016
851
368
63
Richmond, Vermont, USA
I have G5200 which uses the very same belt setup.

First of all... I order my matched-pair belts from ==> https://www.usabearingsandbelts.com/

If you search for the belts (Kubota PN ==> 66021-25080) ... there are many places which sell them.

BEWARE: The originals are METRIC belts.... some sellers are pedaling 'equivalent' SAE (inch) belts which are NOT metric. The shape of the "V", width, as well as the length is not quite correct.


==========================
Also: I was having issues with my belts shredding. (especially in the fall when I used my mower to shred dry leaves on the lawn)

The #1 thing with belts is ALIGNMENT of the shives so I made some measurements.
It turned out that my idler/tension pulley was not aligned with the two V-belt pullies. There was slop in each of the pivoting sections. After correcting this issue, the belts seem to last much longer now.

=========================
If your belts are actually SMOKING.... they are rubbing on something they are not supposed to be touching.

With engine NOT running, engage the deck-belts and carefully inspect the belts.... they should not be touching ANYTHING except the two V-pullies and the tension pully. Pay careful attention to the belt 'keepers' which are intended to prevent the belts from jumping off the pullies. It is OK if the belts touch the 'keepers' WHEN NOT ENGAGED... but should never touch the 'keepers' when in operation.

INFACT: Touching the 'keepers' when NOT engaged helps the belts come to a stop.

I'm wondering if I could get away with just using normal V-Belts. It seemed the teeth on those PTO belts just wore off quickly anyway.
The 'teeth' on those belts are for COOLING. (cooling fins)
 
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Torinodan

Active member

Equipment
T1600, G4200, G5200, Ford 2810, 1974 Wheel Horse C100
Oct 14, 2021
199
94
28
Fayetteville GA
Also see that the lower pully can turn by hand with the belt removed. Twine and grass knots around the blades and spendles, low lube in the gear box, and dry bearings can cause too much drag.
Do you still have the sticker on the pto side that shows correct adjustment of the spring tension? This will be a little different if you use SAE not metric belts.
I agree with Bruce that cogged/toothed belts help with cooling.
 
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GreensvilleJay

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Equipment
BX23-S,57 A-C D-14,58 A-C D-14, 57 A-C D-14,tiller,cults,Millcreek 25G spreader,
Apr 2, 2019
11,421
4,908
113
Greensville,Ontario,Canada
re: the lower pulley I noticed has a spot where it is bent inwards towards the outer belt,
hmm.. could this be a sign that the shaft the lower dbl pulley is on is slightly bent ?
Try placing a straight edge next to it and spin the shaft/pulleys and see if the gap between pulley and straight edge remains constant. if it 'weebles or wobbles' the shaft is bent.
also...is the idler pulley 'on center' with the 2 pulleys ? Using a tight piece of string between the pulleys ,you'll be able to see where the center of the vbelt should run on the idler.
As other have said, you need to replace the belts as pairs.
 
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Torinodan

Active member

Equipment
T1600, G4200, G5200, Ford 2810, 1974 Wheel Horse C100
Oct 14, 2021
199
94
28
Fayetteville GA
Those lower pulleys bend and dent easier than one would thinks. The PTO shaft can take a pounding.
 
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