

Ski-Doo’s rMotion X Rear Suspension
Tech Shorts
October 27, 2020
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The current reference point in snowmobile rear suspensions is the rMotion, but the new rMotion X takes the bump absorption and anti-bottoming capabilities of the rMotion to the next level.

Every part of the rear suspension has been analyzed and revised to optimize performance in an effort to increase suspension capability and comfort, reduce weight, refine geometry and give riders more options than ever before.
- The rMotion X is the continued evolution of the rider-forward ergonomics started with the original Ski-Doo REV platform in 2003. Since that time, chassis and suspension designs have continued to progress in response to the forward bias of rider positioning on the snowmobile.
- Boasting a five pound (2.2 kg) weight reduction, the lighter weight suspension reduces the unsprung mass for an even more compliant ride. Part of the weight reduction comes from a new lighter weight wheel design on both the large diameter rear axle wheels and small diameter idler wheels.

- The rear arm has been further refined and is now 40mm longer and lighter. Revised geometery and a 15mm longer rear shock increases rear arm travel by a full inch (2.2 cm) with a longer stroke to spread out the impact forces of a bump.

- The front arm of the rMotion X rear suspension is now 30mm longer, which places the pivot point on the rails clearly behind the rider’s seating position. The front arm mounting point on the suspension rails is now 7mm higher as well. By extending the length of the front arm and raising the mounting point on the rails, Ski-Doo suspension engineers reduced the angle that bump forces are transferred into the chassis. The machine will act more like it has a lower fulcrum point, with reduced pitching and rocking of the vehicle in bump conditions. This placement also aids in creating a more ideal balance of weight transfer, back and forth between the track and the skis.

- Riders will notice a greater tendency of the vehicle remaining flatter through mogul sections with greater shock control of the rebound action, or release of the bump energy from the compressed shocks. Again, the rider will experience reduced pitching and rocking of the vehicle in severe bump conditions.
- All rMotion suspensions, including this new X version, use the best matched length shocks for different track length versions of the suspension, rather than a one size fits all approach – assuring the best level of bump performance for each track length.
- Additional adjustability was also added to the front arm with an eccentric cam on the rail mounting position. Riders can fine tune this mounting position for more aggressive or more playful riding by choosing a flatter or steeper angle (1 degree difference) that will affect weight transfer. In the lower position the sled will tend to carry the skis higher, desireable for riders who would like to float over the tops of the bumps at higher speeds. In the upper position the sled will better hold the skis to the ground for improved cornering capability on smooth surfaces, such as trails and forest roads.

- With greater balance of weight transfer, the RAS X front end and Pilot X skis better grip the corners at a more predicatble time for a rider to aggressively attack their desired line. The result is more confident machine response, especially in on or off throttle conditions where weight is being shifted front to rear (traction) or rear to front (handling).
- One must visualize the suspension components from each extreme end of the suspension travel cycle, from full extension to full compression, all while maintaining desired shock motion (leverage) ratios and track tension. Developing a progressive suspension this complex and packaging it within a conventional snowmobile tunnel takes both innovative thinking and a huge commitment.
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