Built by Racers for Racers
The 1976 oval race season ended just like it began in International Falls, Minnesota in early December 1975. Checkered flags were flying for riders on the new Mercury Sno-Twister. The final curtain call came at the last race of the season in March ‘76 with more race wins. Looking back on a phenomenal three years of racing success that was cut short leaves one wondering what might have been had Mercury continued to race in 1977.
A Brief History Lesson
Kiekhaefer Mercury, as the company was known, entered the sled business in 1968 with excess capacity to manufacture additional engines. Entering the snowmobile business was a way to utilize that excess capacity of the casting plant. Trouble was, Mercury underestimated the type of engine they needed – a high revving snowmobile engine. Mercury’s own 644cc twin put out only 35 hp in 1972. Yes, they had work to do. As we all know even today, snowmobiling technology advances quickly. Simply put, you can’t just sit still and maintain market share.
The snowmobile business matured very quickly in the early 70’s. New engine technology, tighter noise regulations plus improvements in clutching and suspension were rapidly advancing. This required huge capital investments in R&D, manufacturing capability as well as racing to stay current. Companies without deep pockets soon fell by the wayside.
Mercury was prepared to weather the storm and change its brand image. They had made the move in 1972 by hiring a top notch engineer (Lyle Forsgren) from Rupp and two stroke engine designer Les Cahoon to work in their Advanced Research Group. These two were part of the brain trust behind the 1974 Mercury Sno-Twister (featured in the Jan/Feb 2007 issue of SnowTech Magazine).
With the success of the ‘74 Sno-Twister, Lyle Forsgren was promoted to Engineering Manager of the Mercury snowmobile division. Forsgren inherited a dismal product line. His efforts would be seen in 1976 with the performance Trail Twister offered to the general public and Sno-Twisters for the race track. There were unique models planned for the 1977 model year that ultimately were never released. More on that later.
Mercury Skunk Works – AKA the High Performance Group
With Lyle now in charge of the Snowmobile Division, he created the High Performance Group (HPG) knowing that he would not have the time to lead a group that needs to be separate from manufacturing and the daily issues that managing production and people create.
The HPG group was to work on the next generation Sno-Twister that was to be ready for action in 1976. The people he needed on the team had to be sharp, self motivated, hands on and know snowmobiles inside and out. Doug Hayes was # 1 on his hit list for the HPG group. At just 22 years old Doug had proven himself to Lyle during the ‘74 race season. At the USSA season-end race banquet, Mercury’s Product Manager and USSA President (John Hull) persuaded the #1 SnoPro Driver Stan Hayes and ace engine tuner Dick Bahr from Polaris to meet with Forsgren. The pair joined the HPG group along with Jerry Witt (ace mechanic) and Bob Mendlesky (Mercury Advanced Research).
I spoke with Stan Hayes about the High Performance Group’s mission; “The intent was to do high performance development and the goal was to develop the geometry for the ‘76 chassis. We basically had most of the winter to figure out what we wanted for ‘76. Lyle told us if racing was required to prove and test concepts then you go racing. He didn’t care if we ever won a race, but the production driver better! You can go racing or do whatever you want, but you have to deliver in the spring. This new sled has to be a winner!”
So, with that set of instructions and a looming deadline, the HPG group rolled up their sleeves and started work in the spring of ‘74. Stan Hayes recalled, “The first sled we built was patterned off my ’74 Polaris 340 SnoPro. I had come off an incredible season with Polaris and my 340 that year had worked exceptionally well that winter. I had recorded all the key measurements (ski width, engine location, spindle angles, wheel base, suspension mounting bolt locations, etc) as reference points over the course of the season as I dialed in that chassis.”
Project “Small Sled”
Doug Hayes remembers, “Originally for ‘75 the rule book was wide open. We were mandated to develop a chassis for all three stock (250-340-440) classes. That meant that every part was put under scrutiny and if it had to stay then we were tasked with making it smaller or lighter.”
In researching these stories I recalled Arctic Cat and Ski-Doo’s foray into building super light scaled down race sleds. Remember the Formula II or Blizzard Élan? Those sleds did not turn out to be world beaters so why was Mercury now following this path to potential disaster? Simple. Power to weight ratio is king, but unlike the sleds of the past, these new sleds were going to be able to corner as hard and fast as the super exotic ‘74 SnoPro race sleds.
“We sat down with Lyle and read the USSA rule book. Lyle told us what he wanted to do. His code name for the project was ‘The Small Sled’. We spent the summer building up a variety of sleds. We made the dies in the HPG shop for the front bulkhead and stamped out the parts for what would be the ‘75 test /race sleds. The rules stated that a production tunnel had to be used but could be modified. The new tunnel could not be shortened, so we made close off panels to run shorter tracks. From the outside it looked like we were running 110”-112” tracks, which we did at times. As the season progressed we settled on the wheelbase we wanted and that meant a 103” cleated track which Goodyear was able to make with existing tooling which reduced lead time and cost substantially.”
“When we went to Alaska with our first protos, we had built sleds with different spindle castor angles, ski stances and a variety of rear suspensions with long and short front torque arms. In those days we still engineered by trial and error along with notes from past setups. Just like today’s engineers we were trying to come up with a balance between good weight transfer off the skis under acceleration and just the right amount of ski pressure when cornering,” recalled Stan Hayes.
“Engine location relative to the front track drive axle was also under scrutiny. Lyle had arranged to have a variety of drive belts with varying lengths so the team could reposition the motor back and forth a few inches. These test sleds had adjustable motor mounts so we had lots of latitude to arrive at the best location in the front bulk head.”
While the Hayes brothers, along with Jerry and Bob, were busy finalizing the new chassis and suspension setup over the winter, Dick Bahr and Les Cahoon were busy going through the math to wring every ounce of power possible out of a new Kohler Liquid Cooled engine planned for ‘76. The ‘75 Sno-Twister ran in the 340 and 440 classes. The ‘76 season would require a new 250 engine so all three classes were covered. Dick Bahr was quickly making a name for himself in the snowmobile industry. “Dick taught himself calculus so he could write his own formulas for tuned pipe design,” recalled Stan.
Kohler engines were built in Toronto, Ontario under the direction of Martin Heinrich. When Kohler would depart the snowmobile industry, Martin’s name would turn up again working with Polaris when it began developing its domestic engine program (think 1997 big-block 700 Polaris twin). Dick Bahr and Les Cahoon realized that the future was with liquid motors to be competitive as well as meet the new 78 dbA noise level regulations that came in effect in ‘76.
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Dick would spend the ‘75 season evaluating porting and piping on the Kohler RS free air motors that would later be used on the ‘76 Kohler RLC engines. The old Kohler RS motors had reached their durability limits with the HP needed to be competitive but the quest for high power to weight ratio finally paid off with wins near the end of the season in both the 340 and 440 classes against Polaris, Arctic and Yamaha. The HPG group had been developing what would arguably be one of the most dominating purpose-built production race sleds. The cool thing about it was they pulled it off right under the nose of the competition.
The HPG group delivered the chassis that Lyle wanted on time in the early spring of 1975. Next up was the annual USSA meeting with the other manufacturers to decide on what the minimum build quantity would be for each class and finalize dimensions and minimum weights. The rules from 1975 required a minimum of 500 sleds per engine class or 2% of total production, whichever was largest. This typically resulted in race sleds getting into the hands of consumers as not all of the sleds were sold to racers. Stock race sleds were evolving into purpose-built race sleds and had no place on the trail. They would break, burn-up and flat out did not work in deep snow.
Doug Hayes tells the story; “Lyle was pushing for the 2% rule again so no ringers could be built. Arctic Cat and Ski-Doo wanted no part of the 2% rule and told the USSA they would build only 500 per engine class in 1976.”
This played right into the hands of Lyle and the HPG group. “On the way out I said to Lyle that we were building a ringer, so why did he vote for the higher build quantity? Lyle explained after the meeting if they had kept the 2% rule we would race the ‘75 Twister in stock again and sell all the ‘76 Twisters as mod sleds for more money. If we don’t build a ringer then somebody else may be doing it.”
The Hot Stocker Comes to Life
With the rules in place, final production planning was completed and purchase orders issued for parts and materials to build the ‘76 Twisters. The USSA rule book required that a minimum of 20% of stock race sleds had to be built for each class and available at dealers by October 15th. The remaining balance had to be built and registered with USSA by December 1st.
The new Twisters were just 90” long and 39” wide with a 35” ski stance. The 250 cc Twister weighed just 1-2 lbs above the USSA minimum wet weight of 320 pounds. The 340/440 made the weight by 10 pounds.
I asked Doug what parts were left off the ‘76 Twister that the HPG group pushed for. “Lyle would not allow us to use the aluminum anodized brake disc. The brake was considered but I had failed one during testing, so it was nixed for safety. The disc and hub were aluminum and the disc hard coated with a standard brake pad. You could get it hot enough that I failed a disc. Mercury did not have hydraulic brakes and cost was an issue. We also wanted to go with titanium cleats on the track but that obviously was not approved.”
Mercury still had not designed their own clutches so Arctic’s Hex primary and Arctic Secondary were used. Arctic Cat at the time was supplying their clutching to a variety of manufacturers for increased revenue as sled sales continued to decline.
With Mercury outsourcing the engines to Kohler of Canada and clutching to Arctic Cat, I asked Lyle Forsgren just how much of the ‘76 Twister was made in-house? “On the 400 Twisters in ‘74 we had a die-cast chaincase. Mercury was so busy making outboards we had to farm out the casting. As the years went on we continued to outsource even more parts. Merc did not have the facilities like Arctic, Ski-Doo and Polaris to make weldment parts (spindles, skis, suspension brackets, etc.). We just assembled. You don’t make much money assembling.” The companies that have survived today always manufactured the bulk of their parts to control costs and manage quality.
As the production schedule was approaching, the first of two issues that almost sabotaged the success of the ‘76 Mercury Sno-Twister struck the HPG group. A strike by production workers lasted from August to October 6th. The USSA deadline of 20% of production of 1650 Twisters available at dealers was due October 15th.
I asked Doug Hayes if the HPG group had to build sleds during the strike? “Yes, all non-union employees had to work on the production line to get the 20% of the total production of Sno Twisters out to the dealers .Even John Hull (President of the snowmobile division) was on the line working. John was installing decals on the hoods, Jerry Witt and I were riveting bulkheads on to the chassis. As I remember that was only for two weeks and the strike was done. John said we were doing about 60 percent of what the regular workers could put out at the end of the two weeks.”
The new ‘76 Sno-Twister was officially unveiled at the USSA manufacturers meeting in Green Bay Wisconsin on September 19th, 1975. Stan Hayes remembers the meeting as a highlight of his career in the snowmobile industry. “All the companies brought their new stock racers to reveal to the press. Doug and I carried the new Twister into the room. Jim Bernat and Bob Eastman were there and walked right over to it. After looking it over with a fine tooth comb, Bob said ‘You boys sure did your homework.’ That was one of the proudest moments of my life hearing that come from Bob Eastman!”
Harmonics and the Thunderbolt Ignition
The new Kohler liquid cooled engines were piston port intake with single exhaust ports and four transfer ports. The Dick Bahr designed exhaust pipes were the real secret behind the motors’ power as well as the unusual round resonator. The resonator used on the ‘75 Kohler motors did not work well on the new liquids. Stan Hayes recalled, “Dick had been struggling to meet the 78dbA noise level and still put out the power the engines need to be competitive. The resonator Dick came up with was round as opposed to cylindrical. This design did not impact the tuned pipes ability to return unburned fuel into the open exhaust port while meeting the new noise levels.”
This was great news except for the fact that the cranks on the new 340 and 440 liquid motors were still based on the ‘74 crankcase, except for the 250 motor. All engine sizes used a 60mm stroke. While Dick and Les were running the new engines on the dyno that summer a problem went undetected – that is, until the first race in Alaska. On the 340s and 440s the primary clutches were shaking apart. It was soon discovered that the new Mercury designed Thunderbolt Ignition with its internal rotor was the issue. This smaller mass rotor allowed the engine to rev quicker but created a harmonic that traveled right through to the Arctic Hex clutch. The 250 motor had been designed with a harmonic balancer on the recoil side of the engine so it didn’t have the issue. Service bulletins were issued in December to all racers to add a balancer to the recoil side of the 340 & 440 motors. This quick fix made a huge difference in the performance of an already dominant race sled.
Future Super Stars and the Final Chapter
Everyone wants to ride a winner and in 1976, the racers that rode the Twister to victories all across the snowbelt reads like a “Who’s Who” list of future World Champions and Hall of Fame Racers. Brad Hulings would win just about every race he entered and would go on to have factory rides with Polaris, Scorpion and Ski-Doo. Jim Dimmerman and Steve Thorsen both raced in ‘76 on Team Frustration and both would be future World Champions.
I spoke with Frans Rosenquist and he summed up his season on the ‘76 Twister like this, “First race of the year I went to Ironwood. I owned the 440 and my mechanic owned the 250. Neither one of us could afford the 340. I bought a 340 and wrote the dealer a check for like $1950 and told them to hold it until Monday before they cashed it. I said I would make enough money in Ironwood to cover the check. When I got to Ironwood there were 150 entries in the 250 class. I ended up winning the 250 final. In the 340 class I crashed out and in the 440 class I took a second. My take home for the weekend was almost $3000.00. That paid for my sled!”
“I raced mostly in the old ASA circuit that winter and I was driver of the year for winning points championships in 9 classes that year. I was then invited to the World Series. It was there for the first time I was in head to head competition with Brad Hulings. He won the 440 and I took second behind him. I had a good enough year that Kurt Degner from Yamaha offered me sleds and parts in 1977 when Merc closed up shop. Yamaha did not have a 250, so I raced my ‘76 Merc. Went back to Ironwood and won again against all the new 250 Cats. I had a great year in 1977 with a 440 Yamaha and a left over Merc. I was the Highpoint leader in USSA, earning me the number 1 bib. After that very successful year I was chosen for my ‘78 ride with the Yamaha factory team headed up by Lyle Forsgren. It really all started for me with the Mercs. I was a nobody until I won Ironwood and Eagle River and placed second in the World Series.”
The HPG group also built up SnoPro Twisters for 1976 that the Hayes brothers raced in preparation for the updated ‘77 Sno-Twister. A new, more compact chaincase, relocated radiator, trick slide rail suspensions that had rails that could move independent of each other were all under test. Les Cahoon had started work on a new Merc engine to replace the Kohler. This motor had bridged exhaust ports as well as the ability to run as a piston port or piston reed valve. The thought here was to run the engine in two configurations – race or consumer. It was nearing completion in February of 1976.
Lyle also had the HPG group focusing on cross-country, which was starting to regain popularity. Lyle had worked at Boeing for many years prior to coming to Mercury and had a lot of experience with Telescopic Strut landing gear. The HPG group had a 6” TSS ski suspension and 6” long travel track suspension under development.
The official announcement came one week after the HPG team won the Soo I-500. The dilemma that Brunswick had at the time was the limited amount of capital to expand Mercury Marine Business. Mercury could not keep up with outboard motor demand. They could sell as many as they could make. The question was do they expand the business to make more outboards or snowmobiles? Sleds sales were decreasing and outboard sales were on the upswing. What would you do? Mercury left the snowmobile business just one year after its biggest competitor OMC pulled out of snowmobiles, which likely had a major influence on the decision as well.
So, what happened to the HPG staff? Doug Hayes would move on to Ski-Doo for two seasons of racing (see the story on the ‘77 SnoPro Blizzard in the September 2019 SnowTech). Stan Hayes would turn his attention to cross country racing working for Ski-Doo and John Deere. Dick Bahr would work for Rotax, Jerry Witt was picked up by Kawasaki and Lyle Forsgren would head up the Yamaha SnoPro team in ‘78 before returning to Mercury working in the Advanced Outboard Department.
Mercury left the game on top and pushed the limits of the leaf spring racing chassis. It was now time for the other manufactures to start to do their homework to beat it.
And the rest, as they say, is now history.
Author Hal Armstrong would like to thank Doug Hayes, Stan Hayes, Lyle Forsgren, Greg McBrine and Frans Rosenquist for the information they provided.
By Hal Armstrong – SnowTech Canada
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