Friday, April 22, 2011

Agilety and Nimbleness

I would like to address the nimbleness of the new Proclimb chassis.  Because of the higher center of gravity and more centralized mass the sled is much easier to move. In an attempt to explain, I will start by saying that any mass, if  the weight is distributed equally will change direction at a given rate. If the weight is concentrated at the ends or outer reaches of the mass it will naturally resist the ability to change direction; on the other hand if the weight or mass is concentrated centrally, the ability to change direction is greatly improved. This is where we have a great advantage with the new mountain chassis, because the heavy components, the engine, the fuel cell and the cooling system and even the rider are all moved to a more central location. This is why we have a more agile and easier to move sled.  Personally I prefer the 153” track over the 162” for the same reason. The 162” only lays 4.5” more rubber on the ground, but this puts the rear axle 4.5” further away from the center point of the sled and effectively slows down the willingness of the sled the move. This of course requires more rider input will tire the rider sooner.
 This leads me to the higher center of gravity issue. Arctic Cat chose to change back to the traditional chaincase drive system as opposed to the gear drive unit we have enjoyed for several years. The most noticeable characteristic that I see here is in fact the higher cg, so how does this affect the sled and its balance? I find that initially the sled is easier to tip or roll up to its edge, the down side is that the balance point is somewhat smaller and makes the sled a little less forgiving. For advanced riders that can keep up with the sled this can actually be a benefit. It’s when I get behind the sled I find that it is much harder to catch up to or when I make a mistake I may not be able to recover as easy as with the M series. For this reason I am forced to ride more aggressively and ride ahead of the sled, this requires that I anticipate more of what the sled will be doing before I get there. Accordingly I then can set myself up to react to what I expect will happen next.
So then what is the real reason that we have a chain case? Primarily due to the Torque Control Link (TCL). Incorporating the TCL with the gear drive system was not possible. The TCL greatly improves belt life by reducing clutch misalignment. Now the engine and driven shaft are mechanically separated , when the engine torques under acceleration the driven shaft must move with it. The clutch center distance cannot change and parallelism is maintained. As well as belt life, the engine feels rippier also. Because the clutch center distance cannot change, the track is driven more positively and responds quicker to throttle input.
Other features include a larger 10.75” driven clutch, magnesium case construction and longer clutch center distance.
I am not sure yet where we stand as far as weight savings, but I will be reporting on this as soon as I have some time to do some disassembly and weighing of componets.

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