Early in the season we were out pounding the slopes and trying to see who had the best sled. There were M8s, Dragons and Summits. And each respected snowmobiler wanted to prove that his sled was the best in all conditions.
The one thing about snowmobilers is that nobody likes to be highmarked. So sometimes the hill would really get chewed up as rider after rider notched his mark high on the slope. Soon, the notches would be every bit as hard to negotiate as the slope. And those on the Summits found that when they tried to bust through the trenches, the front of the Ski-Doos had a tendency to lift up, causing two things to happen. First, handling was greatly diminished. Second, less track was in the snow, meaning less traction.
Apparently, others have found the same issues with the Ski-Doo rear suspension.
"At first we started playing around with the front shock springs," explained Tom Dines at Tom's Snowmobile Service. "We started with lighter springs, which seemed to help. Then we went to Fox Floats, which really helped."
Before long, Dines had designed an entirely new rear skid frame for the Summits-the Evolution Air.
Dines has gained a reputation as being one of the West's top Fox Shox specialists with Ski-Doo snowmobiles. The editors of SnoWest have worked with Dines on numerous projects throughout the years and have always enjoyed great success.
We recognized early in the season what Dines had noticed with the Summits-the stock suspension ride was unpredictable and the sled had a tendency to trench in the powder and push through the corners.
As Dines made the refinements to his Evolution Air suspension, he found that not only did it make the weight transfer more predictable, but now you could move up and down the running board and create more of a nuance in handling and control.
"Some people like ski lift," Dines explained. "The Evolution Air puts you more in control." He said stock sleds required the rider to be forward-mounted. With the Evolution the rider can move back without losing stability.
This really became noticeable while highmarking. After we fitted our test sled with the Evolution Air we could cut through the highmark trenches without experiencing ski lift. The Evolution Air Increases Control suspension deals with the bumps while allowing the sled to remain level.
The Evolution Air kit is fairly simple. It includes the two Fox Float shocks, two torsion rods, a rear arm with Dynamic Stops and the necessary hardware. Other than the parts you're replacing, you basically use your stock skid. However, you do eliminate the torsion springs and front track coil spring, which saves you about 10 lbs.
The nice thing about installing the Evolution Air is that you don't have to do any chassis modifications. It bolts into factory positioning so no drilling is required and fits a 146-inch, 154-inch or 163-inch rear suspension.
The step-by-step instructions are fairly easy to follow (as far as instructions go). And for most, the hardest part of the process is just the initial removal of the rear skid frame (those four factory bolts will play games with you unless you have air tools that can break a bolt loose... when trying to use hand or electric tools, the bolts tend to spin in the axles).
The Evolution Air is very clean and open, which tends to allow the dispersal of snow in the track. which means you don't pack extra weight in the rear with snow buildup. And not only do you have a better suspension, but you have a more adjustable suspension, allowing you to tune for your size and riding style and make easy on-the-trial adjustments as needed.
Dines started working on the suspension during the 2008 riding season. Last winter the Evolution Air was released on the market, although Dines continued working out some small glitches and refinements.
But to get the best results, Dines says you have to deal with the complete package of the Summit-you have to consider the clutching, suspension and the skis. Once you tune to the strengths of each of these three components, you shouldn't have to worry about those pesky highmark trenches.
Tom's Snowmobile & Service is located in northern California and has been involved in the snowmobile and ATV industries since 1985. It is a Fox Shox distributor. It also offers Triton Trailers and a full line of performance parts and riding gear.
For more information go to www.tomssnowmobile.com.