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48" wb belts out after 50hrs


LawnSite Senior Member
kenosha, wi
i have a ~2002 snapper 48" belt drive wb .. and the drive belt, the one from the clutch to the deck keeps wearing out and busting in 50 hours.

i looked with the blades engaged and the belt tensioner pulley that swivels on that little arm is "vibrating" back and forth really fast .. about 1" of travel. causes a decent amount of vibration.

with the belt off it doesnt seem like the bushings for that little arm have play or anything. then there is that big spring that pulls the arm to keep the belt tensioner pully on the belt tight; spring seems fine but i guess i wouldnt know how strong it should be. what parts do you guys think i should try replacing?

i read on here a while back someone said old pulleys wear belts down fast, but i dunno, the only thing that seems possible is that the spring isnt tight enough.

thanks, hopefully somebody has seen this before.


LawnSite Fanatic
Are you using a OEM belt ?

I have seen wrapped belts installed in place of raw edge belts and they will not hold up.

Another thing,
If the spindle pulleys are cast iron check the top and bottom of the V area for a groove. A groove worn in the pulley will cause the belt to run on the inside flat area instead of the sides.

If the pulleys are steel after a period of time they will spread open and let the belt ride the inside flat area instead of the sides.

The spring could be weak and for a few buxs it wouldn't hurt to replace it.
I have also seen new Gravely WB's we sold years ago that the belt being so long did do quite a bit of slapping back and forth but didn't cause any problems.


LawnSite Member
I bought a new 48" Toro Gear WB last summer and my belt was dancing all over the place. The mower has a one belt system which makes the belt to long and that is why it dances around so much. I kept thinking the belt was just not tight enough so I kept messing with it till I over tightened it and it broke, cost me 90.00 for a new one. I am going to modify it to a 2 belt system because this design is flawed.


LawnSite Fanatic
I am going to modify it to a 2 belt system because this design is flawed.

So, What you are saying is every mower on the market with a long belt that "Dances" is a flawed design ?


LawnSite Member
long island
in fact the one belt system imo is one of the greatest innovations....that much less parts to wear out...with two belts u need more pulleys, tensioners, belts...


LawnSite Member
I work as a mechanical vibration analyst and it is a fact that it is more difficult to set the correct tension on a long belt because of the increased force deflection, that is why it vibrates more than a shorter belt. The less vibration you have will mean an increase in the life of the friction components such as bearings and pulleys.


LawnSite Fanatic
To a point, the best I can recommend is running the mower at around 90% of Wot, that's what I do a lot of times and it seems to help, just a notch below full.

Yeah my belt dances and I can never get the tension right and I've replaced bushings and bearings until I couldn't see straight, I'm talking I got so anal I was adjusting tension while it was running and with digital tension testers yet it seems the only time it acted right was for the first few hours when it was brand new and half likely that's only because I couldn't see what it was doing under the deck yet. :laugh:

It's sick, by the time the dancing is gone the belt is too tight, loosen the belt a tee bit and there comes the vibration... There's but so much you can do, as a general rule I like for my belts to be about as tight as an automotive alternator belt, somewhere along those lines.

The one thing that helps is always keep a spare in the truckbox, but if you're wearing OEM belts every 50 hours I think there's a bearing or bushing needs replacing... If a spindle's doing it, it's possible the whole thing has to be replaced in one piece, that or you're running too tight or loose but idk...