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How to Clean Snowmobile Clutches

Step-by-step instructions for maintaining your drive (primary) and driven (secondary) clutches
Snowmobile clutches have a difficult life. At the flip of a throttle lever, they go from idling to transmitting full power from the engine’s crankshaft to the chassis’ jackshaft. They must perform shifting duties under harsh conditions and rider styles from mild to wild.

Poorly maintained or worn out clutches can steal torque and horsepower from the powertrain. Issues often include misalignment of the clutches, worn bushings or rollers, or worn or incorrect drive belts. The basic flyweight-style drive clutch dates back to the early 1970s. The principles of operation apply to most any flyweight-style drive clutch used by Arctic, Polaris and Yamaha, plus the Comet series of clutches from the vintage 1972 model 100-C to the modern 108-EXPs.


CLEANING THE DRIVEN (SECONDARY) CLUTCH

STEP 1

The Launching Point: Cleaning and calibrating a Cat driven clutch includes having a serviceable secondary, tuning parts like helixes and/or springs, tools and cleaning supplies on hand.


Like the driven (secondary) clutch, the drive clutch (also called the primary) needs a thorough inspection prior to the season. There are a few more parts, so follow closely.


CLEANING THE DRIVE (PRIMARY) CLUTCH

STEP 1

Removal: No matter what brand clutch you have, it’s best to have the proper pullers to install and remove the drive clutch. Note that some brands’ pullers or holders can damage other brands clutches, while some pullers directly interchange. Use a proper holder to allow the retaining bolt to be removed or installed, and then make sure to put a dab of grease on the end of the puller bolt and threads to ease use. Thread in the puller bolt until the drive “pops” loose from the crankshaft taper.

NOTE: A proper drive clutch puller designed for your make and model clutch is required to “pop” the drive off the tapered end of the engine crankshaft. Many clutch pullers and holding tools are not interchangeable between style or brand. Using improper tools may actually cause damage.
More clutch calibration basics
For calibration, a lighter flyweight allows for less belt pressure at a given RPM, allowing higher engine RPMs, while a heavier weight will reduce max RPMs with increased belt pressure. How the mass is distributed on the weight can also change the operational characteristics. For example, mass along the tip will have far more influence than mass around the mounting hole. The shape of the weight can also influence the engagement RPM. Features such as a flat or a notch for the roller to sit in at idle increase the engagement RPM above what the spring would do alone with a smoother ramp profile.

The secondary clutch is a load-sensing unit that primarily controls shift-out and backshifts. Also, it influences top engine RPM and load. The secondary helix was introduced in the late 1960s and was quickly adapted across the industry. The now-common reverse helix design was brought to the world by John Deere for the 1976 model year. Roller driven clutches, introduced by Aaen Performance in the early ’90s and then popularized by Arctic Cat in the mid ’90s, might be something we take for granted now. But at the time, a driven clutch that backshifted (or downshifted quickly) was a significant upgrade in state-of-the-art clutching.
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