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Among Ski-Doo's many hits have been the original Olympiques of the 1960s and the REV series of today. Yet, the company that got the world to play in the snow has had its share of misses too.
One was the front strut-suspended Stratos introduced in 1987.
A couple seasons earlier, Ski-Doo introduced its Formula models with a "performance" trailing arm front suspension to combat Polaris' popular Indy. Obviously more complex and expensive to produce than a traditional leaf spring front ski suspension, Ski-Doo sought a design that would smooth out bumps, offer more precise steering and be less expensive to make than the Formula trailing arm design.
Struts seemed a logical choice. Yamaha had been using struts for a few years. Just before John Deere got out of snowmobiling in the mid-1980s, it had not only played with a strut setup, but was planning to bring it to market. Struts were an acceptable alternative for a new Ski-Doo trail model and the Stratos would pioneer the concept in Ski-Doo's 1987 lineup.
The front suspension's external assembly was concealed with a boot to prevent snow and ice from mucking up its operation. Under the new-for-'87 high-impact resistant Metton hood, there was a coil-over-shock mounted in a tower and literal square peg in a round hole steering assembly. The square peg was grooved to fit into the steering tube and designed to prevent sloppy steering. Ski-Doo felt confident in defining this system as an "independent Posi-direction suspension."
It all worked, but the setup required extra room under the hood to house the two towers and steering assemblies for each ski. While Ski-Doo's design engineers have always showed above-average styling panache, the Stratos was an obvious challenge. The sled looked like a fat-ankled granny with a butter-fed waistline.
Two sleds were offered with the new suspension. The Stratos was the sportier model while the Escapade was to appeal to two-up snow travelers. For power, Ski-Doo opted for its 496cc Rotax fan-cooled twin equipped with the new TRA clutch that had been introduced in 1986 for the Formula Plus.
As a replacement for the "square shaft" design that would continue for a number of seasons, the Total Range Adjustable Clutch featured external adjusters on the clutch cover. Engine rpm could be raised or lowered in 200 revolution increments without sacrificing engagement rpm. The design was able to handle the higher torque and engine speeds the newer Rotax engines produced and offered excellent tunability for trail riders too.
Mated to the "503" series Rotax twin, the TRA clutch helped the quick revving powerplant get up to trail speeds quickly - the Stratos was extremely responsive at low and mid-range levels. The engine peaked quickly, but proved excellent at powering out of turns and was a solid performer for high mileage touring riders.
Started in 1982, the TRA was a joint effort between the "snowmobile" engineers at the home base of Valcourt, Quebec, and the "motor" engineers at Bombardier's Rotax-Werkes in Gunskirchen, Austria. The motor guys developed the clutching to work with the higher performance engines they were developing on their dynos for future Ski-Doo sleds and the snowmobile guys field-tested the powertrain, offering suggestions and direction for the real world.
As veteran snowmobilers know all too well, what looks great on a dyno may disappoint on the snow. This collaboration between Rotax and Ski-Doo engineers lasted four years and resulted in a fundamental design that has carried forward to today.
Other design cues on the Stratos were its externally mounted rear shocks to control the Torque Reaction slide rail suspension and "Heat Flow" hood that diverted engine heat toward the rider.
Outfitted with a wide 16.5-inch track, this sports sled fulfilled its mission of offering good value in a trail machine. However, the Stratos and Escapade would last just a few seasons before being displaced by a totally new Safari series with a newly designed front ski suspension - the Transverse-A. But that's another trip down memory lane.