When belts "go bad"

[hanz63]

I'm sure everyone has a theory. Belts wear out. They do. What about when you see a low hour machine, all looks happy sans the belt. No debris. No problems found. I could give a few examples of these that didn't make sense. Like low hour traction belts on small zero turn. Today was Husqvarna day with traction belts that dropped off the driven pulley. These machines have some time on them though. You hold up the belt and might detect minuscule edge wear. Or not. It isn't like the rear MTD belts that wear uneven due to the VS pulley set up. Due diligence always includes checking transmission mounts and torque brackets. Idler quality for sure on these. It's like when you have a few of these in row, that rather than just a cursory inspection on a PM - just suggest replacing them at X amount of hours. Anyone here do that?

[KE4AVB]

Personally I inspect all the belts whenever a machine comes in if there is a reported problem or not.

It depends on quality of belts, wear of pulleys, that belt retainers are in the correct place or missing completely, and if the v-belt is within specs. Especially pay attention to the plastic v-idlers as they wear the most. I had only a couple where new drive belts fell off the drive pulley (engine) on JD series mower even all the belt retainers in place but they only fell off upon use and disengagement. That was because JD changes to the belt path which an one inch shorter belt was needed and they noted the wrong serial number break on the IPL.

Here most my problems were rooted in the after market belts I was buying. Nearly every one of the problems were traced back to belts being too short causing excessive wear everywhere in the belt path. Belt life times were extremely short on one Husqvarna LO2448 where the user was only getting about 20 hrs max. I just serviced that mower this month where I put on the proper length Kevlar deck belts and customer had gotten over 70 hrs and probably would gotten more if it wasn't welds breaking on the deck which has over 700 hrs on it. It wasn't the quality of the belt but was sizing. It is just a shame that they would not check the sizes themselves instead they depended on their supplier which was a huge mistake. Just can't trust what is printed on the packaging or even if correct SKU is printed on the belts as mistakes can happen where someone loads the wrong belts.

I even had one supposed OEM spec'd aftermarket belt l that literately melted the cords and blew apart after only 8 hrs of use on the same LO2448. Of course when I call to check vendor to see if it was a Kevlar and they informed me it was a poly belt. Now I did last year get in a set of belts from Stens that were actually an inch too long.

With all mis-spec'd v-belts I ended up buying the v-belt measure tool that I currently have and I now I check every belt upon arrival, even the OEM belts. Even they are off at times. If I am belt problem on a machine I go ahead remove that belt and check it for sizing against a known spec. Yes it cost nearly $200 for my v-belt tool since I have two extensions on it but it has save me a lot of wasted time in just the last year.

Something else to be aware of Kevlar belts can stretch up to one percent but poly belts can stretch anywhere between three to five percent. And with poly belts that stretch can be permanent if they cool while under tension.

Note: This is just my experience with belts others will probably have different set of problems.

[hanz63]

All good info. For me it comes down to KNOWING if the belt is in spec or not. Spec can mean a lot of things. Honestly a couple of these belts layed back to back looked so close to new. the old belt seems more flaccid and more apt to drop off is all. Really, if I need to pull off a belt to inspect it, a new one pretty much goes on.
I know the big H will change belt coatings from time to time , which if I remember right has to do with grip vs slip. I used to think they were specific in their purpose, but everything now seems so mixed up. You'll get a belt that is tan now, that a year ago came in as salt and pepper, which before that was something different.
And then it's dealing with General Transmissions wonder CVTs. What crap. Worn belts, broken variators, worn out axle bushings (automatic wheel lubrication system.) Oops, we didn't design these to keep the grass and dirt out of the works . Why would that be a problem on a lawnmower? My distributor quit handling parts. I looked up an assy today , which of course they don't stock. List was over $600. It seems apparent to me that GT is riding the wave of online commerce and selling direct on Amazon and dropping distributor service. At least in my little area of the world. And then I could buy the whole transmission , have it in two days for $375. From a customers perspective , repair or replacement of this transmission along with the rest of neglected Pm brought up to date gives them a ready to mow tractor for 1/2 the price of a new one. Which will disappoint them again in another 125 hours. If cars are like this now too, are they the same disposable units as in LnG?