Western has designed a rear snowmobile suspension system that will provide a range of rising rate motion ratios that are appropriate for aggressive riders and yet comfortable and maneuverable for trail riding. This innovative rear suspension system features 6 different motion ratios with an almost infinite range of adjustability. At one extreme is a progressively rising rate motion ratio suited more to stand up riding or snow-cross. At the other extreme, the suspension exhibits a slight falling rate motion ratio with a rise during the last 20% of compression, more suitable for softer trail riding.

Further, this unique suspension geometry completely changes the way a snowmobile transfers. Instead of relying on increased tension on the top of the track during acceleration to initiate rear transfer, this suspension responds to body positioning. If the rider leans forward while accelerating hard from a stop, the skis stay on the ground. This allows the rider to corner flatter and slide the rear of the sled around on tight trails. Accelerating hard from a stop while leaning back, the skis rise 6-8” and stay there, allowing for maximum traction and excellent deep snow maneuverability. In addition, the track tightens during acceleration eliminating track ratcheting issues associated with most other designs.

This invention demonstrates the following improvements over current technology:

• More comfortable ride
• Improved handling
• Elimination of track ratcheting issues

Potential licensees for this snowmobile suspension will likely be O.E.Ms and after- market suppliers.

Functional Prototype.

This custom suspension has been demonstrated on a Yamaha RS-Rage with the following additional modifications:

• a new exhaust system with a better exhaust tone (10 lbs lighter than the stock system)
• a new lightweight seat that moves the rider up and forward (7 lbs lighter)
• handle bars were adjusted up and forward
• a new lightweight gel cell battery located in the seat (removed 20 lbs from the nose of the machine)

Please contact The University of Western Ontario for further licensing information.

Watch a television clip of this technology, as broadcast on Rogers First Local.

Statistics provided by International Snowmobile Manufacturers Association (ISMA) indicate that in the year 2003 there were 114,927 estimated snowmobiles sold in the United States and 50,209 units sold in Canada. The total value of units sold was $779.2 million in the United States and $291.2 million in Canada for a total in excess of $1 billion. The value of suspension systems alone is estimated at about ten percent (10%) of this amount, or $100 million.

When designing the rear suspension system, most companies utilize various falling rate motion ratios to provide a soft ride. However, when fast riding and jumping they tend to bottom out. Alternatively, sleds designed for racing, tend not to provide the comfort required for long rides. Another area of concern is weight transfer. To improve traction, a snowmobile rear suspension may be designed or set up to provide a large amount of rear transfer. While straight- line acceleration is improved, cornering stability suffers, especially while applying large amounts of throttle.