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Belt Failure and What to Watch Out For

A Few Things About Your Belt You Should Know:

As we all know, UTVs are notoriously hard on belts. This has become especially true as manufacturers continue to roll out new models with even more horsepower than the year before. And we haven’t even mentioned the tendencies of most UTV owners to mod their vehicles until they’re almost unrecognizable from how they were bone stock. Belts have been evolving as well, in an attempt to keep up, but one can’t help but think they’re fighting a losing battle.

Belt Load When you stand on the gas pedal, all the horsepower of your machine is rapidly funneled through a thin strap of rubber to the ground. As your machine accelerates, the clutch applies an immense amount of pressure upon the sides of your belt. The belt also spins, forcing the secondary clutch to rotate. Combined, these actions can generate a lot of heat, even resulting in extreme temperatures that can damage your belt.

Belt Life Expectations “But belts are designed to handle heavy loads and high temperatures.”

To an extent, yes. Belts are designed to withstand the loads that stock machines place upon them. Assuming, of course, that the clutching is set up to deliver the load properly. We’ve seen stock clutch springs and weights that measured over 10% out of spec. 10% out of spec wouldn’t necessarily mean 10% less belt life, but it could mean 10% more heat and friction on the belt. Taking a belt that usually runs 200 F up 10% to 220 F, could take hundreds of miles of the life of the belt.

But let’s be honest, where’s the fun in keeping your machine stock? Mods affect clutching and clutching plays a major role in either shortening or preserving belt life. If you put on larger rims, or heavier tires, you should probably change out some weights and springs. Reflash the ECU, or add a turbo? You should probably change out some weights and springs. The goal is to run at peak horsepower RPM, and have the lowest belt temperatures. This will be the best balance of power and belt life.

Belt Composition The main component in any belt is rubber. This rubber may incorporate fibers or be coated with cloth, but it’s still rubber. And rubber is susceptible to heat. Certain temperature thresholds cause the physical properties of the belt to change, shortening its effectiveness and longevity. Many belts also consist of tensile cords wrapped in an adhesive gum or glue. These cords give the belt rigidity and reinforce the strength of the belt. If you’ve ever had a belt completely shred, you know exactly what these cords look like.

2 Ways That Belts Fail

Belts fail for many different reasons. However, they usually seem to fail in one of two ways.

1. In Large Chunks The belts we’ve lost over the years have taught us a few things. The first of which is if your belt broke apart into large chunks, shock load was likely a contributing factor. When you hit the whoops or jumps, you’re shock loading your belt. Allow us to explain:

With your tires off the ground, your secondary clutch is rotating with much less resistance but when your tires hit ground then load instantly increases. This will cause the secondary clutch to rapidly close, slamming against the belt. You can imagine that as the secondary slams close, it will instantly begin to stretch the belt apart because the primary clutch hasn’t had time to react and shift properly for the instant wheel speed change. This causes an immediate change in the length of your belt, and weakens certain portions of the belt. There are other ways to shock load your belt, but we’ll leave that discussion for the comment section below.

In order to show you just how easily shock loading can occur, here's a short video from TEAM that explains how a CVT operates:

2. In Small Pieces Belts that fail in small pieces have generally been used beyond their capability. Throughout hours of heavy use and repeated exposure to high temperatures, belt integrity is lost and belt properties are changed. Over time the lost elasticity eventually builds up energy and tension, until the stiffer worn out belt can’t handle the load and essentially explodes - often taking out some of the clutch cover, or even a clutch with it.

These are just some of the things we’ve seen as we’ve rode, and here’s a list of things you can keep your eyes out for as you ride. This list contains signs that your belt is wearing down, before it breaks and leaves you walking back. If we missed anything, please let us know in the comment section!

Things To Watch Out For

  • Belt Smell

  • Belt Noise

  • Unresponsiveness in Throttle

  • Infrared Belt Temperatures are fast to increase, and slow to decrease when on and off the throttle

  • Deterioration of Cloth Coating of Inner Cogs

  • Cracks or Separations

  • Missing or Worn Cogs

  • Glazing (Shiny parts of the belt)

  • Hourglassing

What Have You Seen?

If you’re still reading this post, we want to know what you’ve seen. Did you see any indicators of belt wear before your belt broke? How did it fail? Leave a comment and let us know!

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