The anticipation every fall for the upcoming race season is shared by race fans and manufacturers alike, to finally get a look at the new race sleds. Today that unveiling happens at Haydays, but back in the fall of 1970 the race fan would catch their first glimpse in the November issue of their favorite snowmobile magazine.
In the fall of 1970 the snowmobile industry and the sport would enter what would be the pinnacle year of the sport in terms of sales (491,000 units sold) and popularity. To put it in perspective, almost every 2nd household in the snowbelt had a sled or was in the process of buying one. As the 1971 race season approached there were 20 manufacturers building race sleds. Yes, lots of eye candy in the pits!
Ski-doo was #1 in sales back then just as they are today. The 1970 season had been a banner year for Ski-doo, winning the Eagle River World Championship with their new star racer Yvon Duhamel and the company’s new Blizzard race sled. The 1970 season had been highly competitive and the competition had introduced three cylinder engines in the 650 and 800cc classes to win the HP war and chequered flags. In 1970 Ski-doo was running twin cylinder engines in those classes and done quite well. Ski-doo and Rotax were up to the challenge and under Rotax chief engineer John Holzleitner started development of their new triples for the 650 and 800 class with the primary aim of defending the World Championship as well winning these premier classes at every weekend race across the snowbelt.
Ski-doo held their cards close to their chest and was the last to unveil their race sled to the public in late November 1970. The marketing team however did use a new tactic to shake up the competition. What they did was post information about their 6-man race team. Ski-doo reportedly had a $1 million dollar budget (equivalent to $6 million in 2018) to operate their factory team on. Yes, these were the days for Ski-doo when money did seem to grow on trees. Ski-doo was not alone fielding a race team with 6 or more drivers and a fleet of sleds for each rider. The 1971 race season turned out to be all out war, where the motto was bring in all the riders and sleds you can manage to increase the odds of winning.
Ski-doo issued a press release as to why they race. Here is what it said; “ Racing at Bombardier ranks among the most important projects, and for many reasons: because it obviously is important to win; because racing is a most valuable sales and promotion tool; and because in the long run, the most important aspect of the racing program – it helps us give our customers a better product.”
Horsepower Alone Does Not Make a Winning Race Sled
Much to the surprise of Arctic Cat and Polaris, Ski-doo returned with an updated version of the (engine mounted on the tunnel) chassis from 1970. The ‘71 Blizzards were actually built on two chassis. The single and twin cylinder version Blizzard sleds were built using an all new aluminum chassis that housed a 15” wide rubber or cleated track. The new triples (645cc and 797cc) were built around a new 16-1/2” rubber or cleated track, which was a big change from the 18” wide rubber tracks used on the 636 and 776 cc twins from 1970. Even with the move to an aluminum chassis and narrower track the new triples added 45 pounds to the sled weight (per Ski-doo spec. sheet). Ski-doo was counting on the increased HP to more than compensate for the added weight to win races.
The background on the development of the aluminum chassis was explained to me by Réal Larochelle, Yvon Duhamel’s race mechanic; “At the time there was the Research Center and the Competition Center. In 1971 the Competition Center asked for a new design with a front mounted engine and cleated track. The Research Center engineering and marketing group was still convinced that the traditional engine on the tunnel chassis was not obsolete. Based on the success of the 1970 Blizzard, an upgrade to a new narrower aluminum tunnel chassis for the new triples plus the new parts under development to improve drive train would make the 1971 race sled more than capable to handle the competition.”
The Competition Centre did get the cleated track they requested. The move to a cleated track was combined with the patented “Ground Leveller” slide rail suspension designed to articulate in the centre of the track. The idea behind the design was to improve ride over small stutter bumps (an advantage for the traditional bogie wheel suspension) while maintaining a more rigid platform for the track to run against. No shock absorbers, only torsion springs, were used to cushion the ride while maintaining track pressure on the snow. On the racetrack the design was soon found to be a detriment in keeping the track flat on the snow for maximum traction. Right after the first race in Ironwood, Michigan the race team began removing the hinged joint of the two rails and welded them together (like the competition) to improve traction.
Track derailing was also a new problem with higher cornering speeds so cogged wheels were added inside the rear idler wheels to hold the track in place. Remember, these were not clipped tracks at the time. Studs for cleated tracks were also in their infancy. All kinds of sheet metal screws were used to prevent the track from skating sideways and ejecting the rider. Ski-doo also offered a rubber track with a 1” lug. The rubber track was recommended for hard packed snow and the cleated track for slush and soft snow. To change the track required a different front drive axle with a 10 tooth drive sprocket vs a 6 tooth on the cleated track.
Carbides Make Their First Appearance
The racetracks of the early 70’s were typically banked ovals. Running high on the bank and using the wall (or other race sleds) to bounce off of to straighten you out to head down the straightaway was the norm and not the exception. The flimsy spindles and skis of the day were prone to shearing off and it was not uncommon to see a sled finish a race on one ski. The engineers at Ski-doo beefed up spindles and the skis and added a new skag featuring 60-degree carbide inserts. Jean-Paul Samson with Ski-doo had the first patent for carbide application for a snowmobile. The carbides went unnoticed on snowy high bank tracks, but once the flat corner racetracks like Beausejour came onto the race schedule the Blizzards were cornering as if on rails for the first few laps. Carbides lasted so much longer that even with the high center of gravity of the big triple Blizzards the driver could steer through the corner rather than slide. The competition knew something was special with those new skis. The mechanics were kept busy working on these new skags all season learning where to position the carbide beneath the spindle for optimum handling. Most teams had carbides by the end of the season and 48 years later carbide skags are still standard equipment.
Drive Train Improvements and Blowing belts
The Competition Department now had a sled with more traction, stronger skis and carbides to handle the corners. With the new triples and more power there was another gremlin that reared its ugly head (and still does today) – blown drive belts! This period of snowmobile development saw the beginning of serious work on clutching, belt materials and chaincase design. Ski-doo had used a stamped steel chaincase with the secondary clutch and brake attached. The design was prone to flexing, resulting in the misalignment of the belt and premature failure. A cast aluminium chaincase, which was not new in the industry, was designed with a separate mechanical disc brake.
You can see from the picture that a torque-sensing link running from the secondary to the chassis front cross member also restricted misalignment.
The primary clutch was a new design that used four flyweights. It still was a kidney weight design. The moveable sheave would slide on a spline to transfer torque. Normal clutch engagement was 6000 rpm. To increase engagement speed the race manual instruction was to mill 1/32”directly over the roller or install the heavier spring used on the single cylinder engine to bump it up to 6500 rpm. These were crude clutches by today’s standards. With the advent of the Polaris flyweight clutch and its success, Ski-doo would actually license the use of the clutch from Polaris in later years and call it the HP clutch. This was the beginning of sharing technology between manufactures that continues today.
The First Rotax Triples and the Secrets of Methanol
The Rotax triples were imposing looking. Listening to these engines with their triple pipes is a bucket list item for all snowmobilers. They were the 12-cylinder Ferrari engines of the day. The sound of them screaming down the long straight away at Beausejour in 1971 is still burned in my memory, 40+ years later.
Ski-doo, like many other race teams, ran the factory sleds on methanol. It was legal back then. Why methanol? More power. Réal Larochelle explained the details; “The Competition Center at Ski-doo developed a conversion kit for the triples. The kit included a fuel rail, special Tillotson HD carbs modified to increase fuel flow and Tillotson fuel pumps to move more fuel from the fuel rail into the carbs. The front mounted fuel tank was factory built with an extra fuel pickup to feed the fuel rail. Ski-doo only offered the conversion kit on the triples to the public but the factory did run some of the single cylinder race sled on methanol also. To burn methanol the engine required some work also. The heads were milled to raise the compression ratio to 15 to 1 and the ignition timing was advanced, exhaust and intake duration were also increased. Another advantage of methanol burning engines is that they ran cooler than gasoline.”
The factory team would cut down the head fins to reduce weight, as the extra surface area was not needed. The factory team put out a bulletin on the mods for the 797cc triple indicating HP increase from 88 hp to 100 hp. Réal said, “The factory sleds had a bit more than 100 hp”. Methanol burning engines were OK for the factories to run who were hell bent on winning at all costs. For the privateer racer, the first time your motor burned down you quickly went back to burning gasoline. The methanol burning engines were banned form competition for the 1972 season by USSA.
Wedge Styling: Classic Ski-doo
The Blizzard with its wedge hood and seat was styled by the legendary Ski-doo designer Sam Lapointe. This styling would be used on the T’NT models from 1970-73 and was a signature design associated with Ski-doo and copied by many back in the day. Sam made an awkward chassis look fast standing still. While the ‘71 Blizzard was cool looking, the drivers struggled with the high center of gravity. The race team soon discovered the shortcomings of their new race sled when cornering even with carbide ski runners. Réal Larochelle explains; “Entering Eagle River we knew we had to get the weight down and try and lower the center of gravity to improve cornering. The seats were cut down, the steering post lowered to just clear the engine and the hoods restyled”. This allowed the driver to lean harder into the corners.
The massive Ski-doo race team and budget as well as Blizzard racers across the snowbelt would win their share of races during the winter of ‘71. A repeat win for Yvon Duhamel at Eagle River came very close until Yvon spun out in the first corner of the last lap racing against Mike Trapp on a 440 Yamaha. The race recounted in the Winter 1971-72 issue of “Race & Rally Magazine” is a must read. Even today it is still regarded as the Greatest Sled Race of all time.
The Ski-doo team headed back to Valcourt after that race knowing that for 1972 their new race sled had to have the forward mounted engine to improve handling. The dominant chassis of 1970 was now obsolete. The history of snowmobile racing as well as other forms of racing is full of lessons learned resting on ones laurels and being beat the following year by some new upstart design. Defeat and victory on the racetrack always translates long term into a better snowmobile for the consumer. I am already looking forward to the upcoming race season to see what is in store for the future trail sled we will be riding!
By Hal Armstrong
Follow our Vintage Rider section in SnowTech Magazine, Follow Hal Armstrong @sledtimemachines on Facebook.
Want more vintage snowmobile stories and photos? You can get the collector’s edition book bundle from SnowTech Magazine and receive all four Vintage Snowmobile Racing books! See below:
Or call 320-763-5411 to order, during Central time hours (9am-4pm, M-F)