Most of us are familiar with how a V-belt works on a front drive system, and we’ve been in a situation where we needed a belt to be a hair longer or a hair shorter. We’ve found that wide and narrow belts fit differently, with the narrow belts riding further into the groove, allowing us to fit a belt that was slightly shorter than the one we removed.

With serpentine drive systems, however, the option of a wide or narrow belt isn’t part of the equation. Belts need to be a good fit, right out of the box, or you can have drive belt issues – especially at higher rpms.

Kevin Redd, with Concept One Pulley Systems, shows us how to mark the tensioner to inspect belt play, and also shows us the proper way to install a serpentine belt. These belt systems use a tensioner to provide tension on a belt rather than a fixed adjustment like many of us have used for years on our old school engines.

Serpentine belts are grooved for better tracking and greater contact with the pulleys, and the smooth side of the belt allows it to ride over smooth pulleys to route the belt around pulleys and and components. This also allows for an entire drive system to function with a single belt rather than three or four belts, increasing the potential for problems. As the belt stretches, the tensioner helps to keep tension on the belt, unlike a fixed system on V-belt drives or non-serpentine type systems with ribbed belts.

In the video above, with the belt adjust marked at rest and at full load, Redd shows us the ‘sweet spot’ on the tensioner, then shows us a supercharged motor revving up and how much the tensioner will move during those bursts. Watching the belt tense up and the adjuster move in the video, you can see how much a belt can stretch as the tension loosens up towards rest.

This example also shows exactly why it’s good to regularly inspect your serpentine belt of cracks and frays, and to replace it before it’s too late. Check out other videos from the Concept One YouTube channel, and visit the Concept One website for specific engine applications, including the supercharged LS engines.