tuning with flyweights and springs

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Ski-Doo changes
When Ski-Doo designed its TRA clutch the engineers were aware of this problem and made the spring pocket larger in diameter and longer. Ski-Doo now offers a big selection of sturdy springs for TRA tuning.

Heel Clicker designed a special clutch cover for Polaris that makes it possible to use the Ski-Doo springs - Supreme Tools has a similar system for Comet clutches.

So far Ski-Doo's is the only primary clutch using a movable roller mounted on a pivoting arm and acting against a shifting curve on a fixed cam. This system was popular on early Arctic Hex clutches and with the short-lived John Deere TR-800 clutch.

The Ski-Doo TRA clutch can be tuned by adding mass to the roller pin to increase shift force, and there also is a large selection of strong pressure springs available. Ski-Doo offers a large selection of cams with different shift curves, matching anything from a mild trail machine to an all out racer.

In addition, the cam can be tilted into six different positions by an eccentric pivot bolt that holds it in place at the top of the tower. Position No. 1 is the most aggressive, while position No. 6 will produce the highest rpm.

The aftermarket industry couldn't leave this design alone, and there are a number of additional springs and cam arms available from specialists like Goodwin Performance, who specialize in Ski-Doo clutch kits. Canada-based Dalton also offers an extensive line of parts for the TRA clutch, and has possibly the widest range of weight kits available. Engineers at Heel Clicker also have been busy making pivot arms where more mass can be added in other areas than just on the roller pivot shafts. This has resulted in arms offering different leverage options, and Heel Clicker also offers optional cams and pressure springs.

Clutching the name of the game
Getting maximum performance from your snowmobile transmission has always been a tuner's game. If you are good at tuning clutches you will have the edge over less experienced competitors. The present primary clutch systems have developed over many years of trials and refinement, and are very tunable to different applications from mild trail machines to all-out monster race machines.

Throw in all the aftermarket tuning combinations and you will have enough tools to choose from to make your snowmobile perform the way you want.