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We tried to sell the shocks to both Polaris and Arctic Cat and although they liked the performance, the Swedes were way above the price the purchase department could justify. When Snocross racing hit its stride, the shock business instead went to Fox who grabbed onto the challenge and grew their business into the snowmobile market with steady innovations and developments. The original Ohlin shock was well made and of high quality, but had no outside adjustments like today’s shocks. They stuck with a steel shock body because they could produce a very fine finish for the Teflon rings on the piston to run against. The steel bodies also expanded less when hot, keeping the clearances close and the performance consistent. The piston had shim stacks on each side for compression and rebound and they could be tuned by building stacks of different thickness and diameters shims. This made the shocks speed sensitive, increasing the dampening power. Early competitive gas shocks usually used aluminum bodies with a hard coating for the piston running surface. This coating often deteriorated, resulting in loss of performance and a need for frequent rebuilds. Today’s modern aluminum shocks use a new and better Kashima coating. These new shocks are light years ahead in both performance and quality.
¦ Better now than ever
Today’s intense Snocross pro circuit has greatly advanced shock technology over the last 10 years. Snocross shocks now have to control 10 inches of ski suspension travel and up to 15 inches of rear track suspension travel. Shock bodies and pistons have also grown in size. KYB bodies are 46mm (1.8 inches) all around, while Walker Evans use 51mm (2.0 inches), and only Arctic Cat uses 38mm (1.5 inches) on front with their Fox air spring Evol 3 shocks, for a very light package. All the shocks are high pressure (250-300 PSI) piggyback shocks and have outside adjustments of both compression and rebound circuits. The compression valving usually has a low- and high-speed adjusting circuit with up to 24 clicks on each, and the rebound adjustment circuit may also have up to 24 positions.
The only shock that does not usually have a rebound adjustment is the front track suspension shock, because this shock is shorter and the adjustable rebound circuit takes up an additional inch of length in the shock eye. The adjustment circuits only fine-tune the shock, so the baseline compression and rebound forces are still controlled by the shim stack calibration on the piston itself. The new shocks also have a position-sensitive feature. This means that as the shock nears the end of its travel it needs additional dampening when the spring forces increase. This is controlled by a bypass circuit that is active as part of the calibration in the first 70 percent of the stroke. There can be holes in the wall connecting into the piggyback and the adjustable compression circuits as in the Walker Evans shocks, or spiral grooves in the body as in the Fox shocks. At the 70 percent point, the piston passes the end of the bleed passages, and the last 30 percent of the stroke then gets a harder compression dampening.
With full factory support, development at the Snocross racetrack is intense every weekend. Fox has a Midwest development center based out of Brainerd, Minn., that does production as well as race calibration for the factories. The manager is Rick Strobel, who has four support vehicles crossing the country, two with shock dynos available. Their Snocross support team consists of Mike Japp and Dan Ebert. The Walker Evans race manager is Ben Hays, son of ‘70s Polaris and Mercury factory driver Doug Hays. Ben started working as race mechanic for Polaris under Tim Bender, then worked for several years with Rick Strobel at Fox, and finally moved back to the Polaris race shop in Wausau. Ben is supported at the races by two technicians from the Walker Evans factory and they all work out of the Polaris support transporter. Ski-Doo and KYB support is handled by Tim Zakarias and assisted by engineering and technicians from KYB often working out of the Scheuring and Warnert Transporters.
This year is a new challenge for both Ski-Doo and Polaris as Arctic Cat jumped them with the longer 136-inch suspension and track last season. Both Polaris and Ski-Doo now have 136-inch tracks and new suspensions that need to be calibrated. Preparations for upcoming races have been intense and fans are eager to see how the new and longer track suspensions perform for Ski-Doo and Polaris in the saga of the Shock Wars.