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Rick3410

PTO drive belt stretching

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Rick3410

I've got my rebuilt deck working great but noticed that the PTO drive belt is really loose after about 4 lawn mows. I do about 3/4 of an acre when I mow and I inspect these belts closely after every operation. I put a 74" kevlar belt on this (Husky from Tractor Supply) and the fit was excellent. Not too tight but nice and snug never the less. The belt came off during my last mow and when I went to put it back on I noticed that there was a lot of play. Is it possible for belts to stretch an inch or so from use? I'm going to take it back to Tractor Supply and measure it to see how much stretch I actually got. Would I be better off trying a shorter belt? Once I measure the stretch I could compensate accordingly. Or, can I expect the belt to keep stretching? The manual says to use a 74" belt. I would think I could get several seasons out of a belt instead of a few lawn cuts. I'd be interested to hear your inputs.

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RayS

The deck belt on my Prestige is original and been on for 12 mowing seasons. Sometimes it is just worth spending the money for OEM belts.

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GLPointon

I agree, I use generic belts for lighter jobs but for mower drive & pto which have higher speeds and tight idlers pulling against 'em, I prefer OEM. I just got a couple NOS "Simplicity" belts on e-bay for less than dayton/napa/etc...BUT, I too have used some "Kevlar" belts with good luck, so maybe you just got a bad one??

Good luck sm01

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MikeES

What tractor is this? If it is a 7100/900 series it could be your idler pulley is slipping and loosening the belt.

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Brettw
quote:What tractor is this? If it is a 7100/900 series it could be your idler pulley is slipping and loosening the belt.id="quote">
id="quote">

I would tend to agree. Belts may wear or break, but I don't think you are going to see that kind of "stretching" from a Kevlar belt. Belts generally do not stretch much, if at all. The Idler setup on the later large frames, have an adjustment with a green/red gauge on it. If this is moving, that could be part of your problem.

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HubbardRA

If the belt is slipping, it will wear away material where it rubs against the "V" of the pulley. This will make the belt appear to be stretched, when really the belt has just worn down and sits deeper in the pulleys. Kevlar belts normally do not "stretch".

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Rick3410

Thanks all for this information. I think that I may be the cause of the problem. I have a small hauling trailer with a hinged gate that lowers and turns into a ramp. I'm sure you've seen them at the local HD or Lowes stores. I was having a problem with the mower deck clearing the transition from the ramp to the trailer platform because it would not raise high enough. I shortened the cable that raises the deck to make it go higher and clear the deck ramp transition. I wonder if doing this is stretching the belt? What do you think?

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rokon2813

If you have the cable short enough that it is carrying the deck while mowing, it could be your problem. These decks are designed to ride on the rollers, and should never be used to mow with the rollers off the ground. The rollers need to ride on the ground, following the ground contours, thus the term "floating deck"

Working correctly, the deck will follow the ground, independent of the tractor, basically the deck is "towed" by the front axle.

this will change the belt angle enough to rub the belt on the rear bar, and changes the angle in the deck pulley enough to wear the belt.

Same goes for the adjustments on the front of the deck. If the front of the deck is too low, it will also wear the belt.

On a hard level surface, like concrete, align your blades front to rear. The front end of the center blade should be adjusted to about 1/2" higher than the rear end of the side blades.

I got a tractor (3414) in that was wearing out belts in no time. After the 3rd belt in 3 hours, I pulled the deck off and totally readjusted everything. The 4th belt is now 2 years old and I mow about 2 acres weekly.

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RickS

As I understand it raising the deck as you describe should not cause a problem with the belt unless you are running the deck at the same time. One should not run the deck in the raised position since it will cause the belt to rub on the deck.

Belts don't stretch usually. Instead what happens is the sides of the belt wear which allows the belt to run deeper in the pulleys. This gives the appearance of the belt stretching.

I would replace your belt with a simplicity belt. While more expensive, in the long run you will save money and time.

Rick......

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Rick3410

This is interesting because the first belt I started with was a Simplicity. I never run the deck in the upper position. I run the tractor but not the mower deck. The only time I put the deck in the high position is to clear the angle on my trailer ramp. I measured the 74" kevlar belt and sure enough it measured 75-1/2 inches. You guys say this can't happen. Well, it did. I just purchased a 73" belt and I'll see what happens with that. It fits snug and if it stretches as well, it should end up around 74 inches. Also, I'll check Rokon 2813's advice on adjustments. Plus, I still have the original simplicity 74" belt that I use for emergencies. It just seems to be really loose but it does work.

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pungo

In the course of my research on these things (mostly here) I seem to recall the pto drive belt by Simplicity described as "A Thresher -style belt designed not to stretch"

I have never found a belt other than oem for my 2010 that did not stretch and become loose. The Simplicity belt was around 40 bucks with tax from my local dealer.

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BLT

My Gates rep when I was in Diesel engine business said point blank, "Premium belts don't stretch over 1/4" on 70" belt. The Kevlar backing is such, that anymore will simply break it." Keep in mind that Kevlar is also used in automotive belts and prior to serpentine drive arrangements an 1-1/2" stretch on 74" belt would cause the fan blade to chew up the shroud on highway trucks.

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Rick3410

Update to the 73 inch belt. I've got about ten hours of mowing on this belt now and have not had a problem. I mow two and a half acres at two different properties. One of the properties has serious hills and the grass grows thick and tall very quickly. Everything worked fine and it is continuing to do so. I guess the 73 inch belt is the answer for this tractor.

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