One of the biggest functional changes found on the Gen 4 REV models from Ski-Doo for 2017 is the new pDrive primary (drive) clutch. This clutch design was first introduced on the 2016 Ski-Doo MXZx 600RS racing snowmobile, and marks a significant evolution in the world of CVT snowmobile drive systems.
This completely new high performance pDrive primary clutch has been designed to reduce friction, reduce weight, tighten tolerances, allow for more consistent RPM delivery, require less maintenance and last longer. To accomplish this the pDrive clutch features unique elements like fast friction-free dual spyder rollers to transfer torque in place of traditional sliding buttons, and the renowned BRP exclusive adjustable clickers – only this time applied to flyweights, needle bearings in oversize rollers and a compact open design that’s also 11mm narrower. The new clutch and new clutch cover combine to reduce belt operating temperatures by as much as 70 degrees F (20 degrees C).
The changeover to flyweights (cam arms) specifically designed with and for the 850 E-TEC is part of its dynamic response and narrow powerpack mandate. But when we come to the function of how the clutch transfers power, one of the true hallmarks of its design is the use of friction-free and self-centering spyder rollers instead of sliders to transfer torque. This provides an incredible improvement in shifting consistency and smoothness, and is part of what you will feel when you ride this new package. It is like the engine is more connected to the track, because it actually is. It also reacts very quickly, in part due to the rollers but also due to the 30% reduction in rotational inertia compared to the TRA. It’s 15% lighter (2.8 lb / 1.2 kg) and 11 mm narrower than the TRA.
And, it is amazingly consistent at holding rpm, keeping the engine at its peak power. In fact, it’s so consistent, Ski-Doo had originally told us there was no need for rpm adjustments (clickers) on the MXZ versions, but after careful consideration all 850s will now come with the adjustment clickers to easily adjust top RPM for changes in operating elevation (altitude) or engine load.
A major factor in the quickness of REV sleds is the new pDrive clutch. Fast and friction-free dual rollers transfer torque in place of traditional sliding buttons on this 100% new clutch. The oversize flyweight rollers with needle bearings, wide flyweights and shaft-on-shaft design emphasize smooth operation and long life. Ultra-responsive shifting, impressive RPM consistency and 2.8 lb./ 1.3 kg lighter than the TRA
In terms of reliability, the pDrive uses a shaft-on-shaft design instead of a single smaller sliding bushing on a shaft. The bushings in the shaft-on-shaft design are placed four to five inches apart for incredible stability. This feature makes a HUGE difference in keeping the sheaves perfectly aligned with no cocking or binding, helping to provide long-term consistency and reliability to the shift characteristics. The moveable design also allows for much tighter tolerances, greatly increasing the long-term durability and reliability. The oversize flyweight rollers have needle bearings (sealed and iso-flex lubricated) instead of bushings and the open clutch design significantly reduces heat, dust, wear debris and rust.
These changes required a significant investment in both engineering and production costs, but they make the new pDrive maintenance free – and a perfect match for the increased reliability and durability offered by the 850 E-TEC. We believe the pDrive primary sets a new lofty standard in snowmobile CVT drive clutches and obsoletes all other primary clutch designs in use today. Seriously, you will be very impressed when you look closely at how this clutch has been designed and built. Very trick, very expensive, and very welcome.