Racing into the future

Ski-Doo’s 1980 lineup of high performance Blizzard leaf spring sleds looked sharp and were certainly fast enough with liquid cooled, rotary valved, twin carbed Rotax powerplants. A trio of Blizzards covered the displacement spectrum of 340 and 440 liquid and 500cc fan cooled sizes, called the 7500 Plus, 9500 Plus, and 5500 respectively.

Good trail sleds they were, but great race sleds they were not. Even the cross-country racing legend Gerald Karpik was known to prefer to race the older late-70s vintage “RV” based sleds for battling it out in the Midwest ditches. The leaf spring and the smooth riding, but heavy handling MX variants were just not competitive against the Indy trailing-arm and SRV telescopic strut suspensions of the day. In response, over the summer of ‘81 Karpik and his team built a pair of racers based on stock Blizzard motors, drivetrains and 5500 MX tunnels, but with an improved trailing-arm front suspension and front chassis. These were often called the “Karpik Specials” and were very successful, winning major “snowcross” races at Alexandria, the SOO I-500 and others during the ‘81-82 season.

■ Racing sled for home
As the consumer Blizzards were improved with the 440cc 9500 being replaced with the 521cc 9700 for 1983-84, more was cooking up in Ski-Doo’s race department. Snowmobilers, racers and press folks were all anticipating a “next generation” machine from the team in Valcourt. A preview was on the way in the fall of 1983 when Bombardier released a new 56 hp class racer, the Ski-Doo Formula M/X Pro Stock.

Bombardier assembled approximately 100 Pro Stocks for 1984, and another 50 for ‘85. Aside from a major leap forward from the leaf spring Blizzards and definitely taking a decidedly more high performance turn over the trail cruiser Blizzard MX, the Pro Stock also gave consumers and racers alike a sneak peek of the soon-to-be released PRS (Progressive Reaction System) IFS chassis-based Formula lineup for the ‘85 model year. Consumers got the first taste of the Formula’s look with the conventional leaf spring front end “SS-25” for the 1984 model year. However, the Pro Stock previewed the sharp handling and progressive-rate IFS front and rear suspension in the Formula Plus and MX for 1985.

■ Geometry gains
The production PRS rear suspension was rated for 6.5 inches of progressive-rate travel, a reasonable amount for the mid-80s. However, this was a significant reduction from the approximate 10 inches on the Blizzard MX. This travel reduction was probably to benefit handling, cornering and lowering the center of gravity, but it was years before Ski-Doo returned to travel numbers like the that.

One interesting note was the track length on the Pro Stock and eventually the 1985 PRS sleds was pretty short. Ski-Doo selected 114-inch length for these sleds, but it was an inch and a half wider than the norm with a 16.5-inch width. Even the leaf spring El Tigres, Liquifires and Interceptors of the early ‘80s ran 116-inch tracks. The Invaders, Indys, ’83-and-up Vmaxs, SRVs and ‘85 AFS Cats ran 121-inch tracks, which ended up an industry standard for trail sleds. Ski-Doo stuck with the short 114-inch length even with a stout 521cc Rotax pulling it around in the Blizzard 9700 and then the Formula Plus. I understand the idea of reduced rotational mass and a shorter machine and wheelbase for crisp handling, but the offset was smaller contact patch and floatation, especially as suspension travel was increasing.

■ Steps in the right direction
If any of this tale seems familiar, perhaps it reminds you of the 16 early release 2002 REV Mod 800cc SnoCross race sleds introduced before the regular production 2003 model year. But that’s another story.