Eagle River – 1975: Legendary Polaris factory racer and race team manager Bob Eastman was standing in the pits after the World Championship race with racer and innovator Gordon Rudolph. Gordy qualified for the ‘75 Eagle River World championship with his latest creation. Powered by a 650 Polaris triple with Independent Front Suspension (IFS), it went up against the best of the factory race teams and qualified for the final. That feat was impressive. Eastman knew that the IFS had a lot to do with his qualifying for the race.
The Rudolph sled broke down in the final and a factory Polaris race sled went on to win. Gordon Rudolph remembers the conversation; “Bob said, Gordy I am interested in the front end of your sled.” Gordy replied, “Well, if I had one of your motors I could beat any of the Polaris factory sleds!” Bob responded, “If we had your chassis we could beat everybody.”
Gordy had been tinkering with trailing arm independent front suspensions since the late 60’s. Leaf spring ski suspension was the norm for snowmobiles at the time but racing had started to show its limitations on the oval track as cornering speeds had increased. The leaf spring was not rigid enough under high lateral loads during cornering. The inside ski would lift off the snow causing the sled to high side, requiring the driver to back off the throttle to keep the sled under control. The early IFS sleds were better at keeping the inside ski planted and the driver in control without having to reduce speed. Chaparral and Bobby Unser had built IFS sleds in the early 70’s and Gordon Rudolph had been improving the concept on his hand built “Gemini” race sleds. The downfall was their reliability. They broke frequently and, consequently, the extra costs did not justify the performance gain they demonstrated.
In January of 1976 the early season race results quickly revealed it was going to be a long cold winter for the Polaris Race Team. The team was running liquid cooled engines for the first time in competition, but the production Starfire chassis was keeping cornering speeds down. Bob Eastman, however, was keeping a close eye on the new Skiroule IFS sleds built by Gilles Villeneuve. The green machines were down on power compared to the Arctic and Yamaha race sleds that year but the IFS Skiroule could be driven faster through the corners, only to lose their lead down the straights. When the machines held together they were impressive.
Polaris finished up the ’76 race season in Beausejour, Manitoba. The team was so hungry for a win that they brought their 1975 World Championship winning 650 triple race sled. In the 650 open class the big triple ran in front for only two laps before the IFS Skiroule with a 440 liquid Kohler engine dispensed of it, leaving it in a cloud of snow dust. Seeing this, Eastman thought back to that conversation with Gordon Rudolph at Eagle River.
Summer of ’76 – The New Kids on the Block
1976 was also a year of change at Polaris with the hiring of Jerry Bunke. Bob Eastman was good at seeing what people could be. Jerry was a great driver but also creative and smart. He took Jerry under his wing that winter and mentored him in the Polaris School of Racing. Jerry was used to winning as an independent and now as a member of the Polaris team losing would not sit well with him, either. Jerry raced stock cars in the summer and learned the nuances of chassis setup from NASCAR mechanic Ernie Tuff who had been part of legendary Daytona 500 winner “Fireball Roberts” race team. Bunke was just waiting for the word to jump at building an IFS sled.
Jim Bernat convinced Brad Hulings to come to Roseau that summer and have a look around. Brad had seemingly come out of nowhere and dominated stock racing on Mercury Sno-Twisters, getting attention and turning a lot of heads. Brad Hulings would join the team in September. The third driver would join the team in December. Bob Eastman contacted Steve Thorsen out of the blue and made an offer to Steve to race for Polaris that winter. Steve hung the phone up thinking it was a prank call. Bob called back again and told him the offer was for real. Steve wasted no time driving up to Roseau and instantly became part of the Polaris family.
There is another part to this story that has recently come to light. Bill Clem is a name that has not yet been associated the history of the RXL. Bill was an industrial design student at the time and had been sending Bob Eastman sketches and models of snowmobiles he had dreamed up. Eastman took to liking Bill and his work and sent photographs of the Villeneuve IFS Skiroule to him that winter. He was interested in his opinion on the design of the sled. Bill liked what he saw and let Bob know it. Bill Clem was hired as a summer student to work in design for the Polaris race team as a 19-year old in the summer of ‘76. Creative things were about to happen in Roseau that summer with youth and industry veterans working as a team to bring Polaris back to the winner’s circle.
Hedging all Bets – Conventional vs. IFS
Arlyn Saage had become the lead fabricator at Polaris since moving to engineering in 1967. JoMar Bernat (Jerry Bunke’s mechanic) described Arlyn as “a person with a keen eye for layout and attention to detail. He has forgotten more about sled building than most people will know in a lifetime”.
Saage was up in Beausejour with Eastman. “After watching Villeneuve walk by Jim Bernat on his 650, I said we better call Rudolph before someone else does. The call was made and Gordy brought up a couple of sleds up to Roseau for the boys to have a look at and drive. We ran the sled on the dirt, outside of the factory. The turning ability is what impressed us. When you turned the bars this sled did not push. The response was immediate and it bit into the ground, hard.”
Back in the race shop the team dissected the Rudolph IFS. Arlyn went through the chassis and noted the similarities to the Unser-designed Chaparral trailing arm IFS. The chassis construction, suspension components and ski design were all put under the magnifying glass.
Chuck Baxter, former Director of Engineering, recalled, “I liked Gordon Rudolph. He was a maverick, an outside the box thinker. You need people like that in any organization if you want to move ahead!”
After spending time on the Rudolph IFS sleds the teams were not yet 100% convinced to put all of their eggs in one basket with only IFS chassis sleds. So much was unknown about the nuances of automotive style suspension design, except for the knowledge that Jerry Bunke had from his time racing stock cars and Gordon Rudolph. It was decided that only two IFS sleds would be built for testing in Alaska in late October. The race team actually focused on designing and building their conventional (leaf spring) sleds first.
The conventional leaf-spring sleds were going to be purpose-built race sleds for ‘77. Polaris was returning back to using magnesium in place of aluminum. Polaris had used magnesium back on their dominant ‘74 SnoPro race sleds. Magnesium is the lightest structural metal available and, combined with its high strength to weight ratio, is perfect for building limited-build race sleds. Arlyn Saage explained that fabricating with magnesium is not simple. “Bending magnesium requires putting the sheet into a furnace at 900F to anneal it prior to bending. You had to make sure you had your bend lines marked prior to going into the furnace, and then we would make two bends real quick before the metal cooled. A complete bare chassis when all done weighed a scant 23 pounds.” Arlyn’s team had hand built parts for 12 conventional chassis’s including three complete chassis prior to the first testing in Alaska.
The Triple-Triple Water Burner is Born
Jerry Shank and Jan Hedlund worked in engine development and in conjunction with engineers from Polaris’s engine supplier at the time (Fuji Heavy Industries). I asked Jerry why a 440 triple was built when everyone else was a running the lighter 440 twin? Jerry explained, “Shake, Rattle and Roll! To make more power you need to run at higher rpm’s. The twin 440 we ran in ‘76 had crank issues when we ran it above 8000 rpm. Fuji was not able to improve the crank so we worked on tightening up the tolerances, but the engine would just come unglued. To make more power we needed an engine we could run at higher RPM without the harmonic vibration issues.”
“The famed 440 liquid cooled triple had origins way back to the early 70’s. We had been running the free air version for years but we knew that liquid cooling was the way to go. Economics dictated that we build free air motors until ‘76. We kept improving the triples from sand cast crankcase to die cast crank case, tighter tolerance bearings and better crank rods and piston materials. The engines were under constant improvement. One area we did find out was that Fuji’s durability testing was not equivalent to our internal testing. We ran the engines under WOT (wide open throttle) on the dyno far longer just to make sure that they would hold together under long pulls across a lake or under racing conditions. A big development made in the early 70’s that allowed us to run Mikuni float type carbs while everyone else was running Tillotson or Keihin carbs was the rubber carb mount between the cylinder and the carb. This isolated the carb from engine vibration, which eliminated foaming of the fuel in the float bowl. We ran the Mikuni fixed jet carbs since 1971, which became the industry standard until fuel injection became the norm.”
“The 440 triple was built way ahead of the ‘77 race sled chassis. We had worked on porting, jetting and water distribution development. The motor was designed to run at 9300 rpm before it started to come apart. We detuned it to run between 8900-9000 rpm. On the dyno the most we got out of an engine was 108 hp. We found out later the Rotax 440 rotary valve motors in ‘77 were producing 120 hp. We did not have the time or money to develop it to run at higher rpm’s. The clutch at the end of the crank also limited the rpm we could run the motor at.”
Coolant flow direction was from the exhaust side exiting out the intake side. We had heating issues and at the time primarily in the cylinder heads with hot spots. We never did figure out the optimum flow rate and coolant flow pattern.
While all the emphasis was on the 440 triples, the RXLs were also built with 250 and 340 liquid motors. Mid season the race team would start running the mono block 340 used in the ‘77 TX-L with porting to produce close to 76 hp. The mono block motor was cheaper to produce and more rigid than the motor it replaced. Cranks kept truer also with the mono block. This motor would also be used in the Indy 340 and 400. The 440 triple would go onto to become the engine that would start the muscle sled boom with the ‘79 Centurion 500 in 1979 and morph into the Indy 600 in the early 80’s.
Meet the Midnight Blue Express Designer
Bill Clem finally got to meet Bob Eastman in person when he arrived in Roseau as a 19-year old first year industrial design student. I contacted Bill and he told me his story. “When I started in June 1976, Arlyn had a conventional sled under construction. Bob had told me the race team had been on thin ice after the ‘76 season, but with a larger budget for ‘77 it was important for the team to make a big splash. One thing I found out quickly was that Bob was a risk taker. That made sense in my mind as after all he was a race driver. I was surprised to also see the Gordon Rudolph sleds in the race shop. It was clear that the team was hedging their bets on everything for the coming season. Conventional or IFS, Polaris was on a mission to make a statement in ‘77.”
In the past Polaris had used styling from the race sleds as the template for the following year’s production sleds. I asked Bill if that was the case for the RXL. “That all went by the way side for these new ‘77 racers. We were told that marketing would only have to give approval for the graphics and the final color. I had a fresh sheet of paper for what was to be a purpose-built design.”
“Bob Aronson, who was an illustrator/designer, brought out a few sketches he had started for the new-look race sled. Bob was the man behind the styling of the ‘76-‘79 TX consumer sleds. The project was quickly assigned to me and I started work with Bob’s designs, Villeneuve’s Skiroule pictures and my imagination. I started work designing the hood for the conventional sled.”
Bill was laughing when he recalled how he made his first model of the hood. “We had no modeling clay to make models from so I improvised. I took welding rod and bent pieces into the shape and made a frame and then used heavy construction paper and hot glue (basically paper mache) to create a model of the hood. I was basically doing 3D modeling by hand. I worked 7 days a week on the design because I was living the dream. Once I had the shape that would fit on the conventional chassis, I laid fiberglass over it and learned how to use body filler to make a smooth surface to sand before priming and painting the hood. Bob wanted the sled to standout and make a statement when it hit the racetrack. White had been the colour associated with Polaris hoods so I went down to the local auto body shop and started mixing up colours. Finally I came up with what would be called ‘Midnight Blue’. I spent hours on decal designs until Bob Eastman approved the graphics that were used on the sled. The exploding star on the right hand side of the hood was also my design!” For an encore Bill would go on to design the race suits and helmet design for what was to become known as the “Midnight Blue Express”.
Bill Clem remembers well when construction of the first IFS sleds began. “The 440 and 250 were the first to be built. Jerry Bunke would spend hours measuring parts and trying to figure out how to simplify them.”
“It’s important to remember that when these sleds were built there was no AutoCAD, Solid Works or 3D printers to design parts and ensure they all fit together without interference when assembled. Arlyn and team were fabricating parts out of their head and from sketches. Once the part was made, the senior design draftsman Al Hagen would create a “Flat Pattern” drawing so that future parts could be replicated faster. Laser cutting was a dream; all the bulkhead parts were hand cut.
They were building two of every part with chassis parts being fabricated by Arlyn Saage, Jerry Bunke, Dalton Lisell and others. The 1977 IFS chassis’s were all aluminum except for one magnesium chassis built for Jim Bernat for Eagle River and later raced by Steve Thorsen with a 250 motor.”
As the IFS chassis’s started to come together, Bill Clem started work on the hood. The goal on these sleds was to keep the center of gravity low. IFS chassis geometry was in its infancy and concepts like roll center and its location relative to the center of gravity on handling were not considered. The radiator however was to be mounted low in front of the engine between the skis to lower the CG and reduce weight. Necessity is the mother of invention and the team had a concern that not enough airflow would be directed to the radiator. Bill Clem explained how they studied the airflow patterns; “George Terry (a fabricator in the Styling Department), Jomar Bernat and myself took a chassis with the new hood design and mounted it on the roof of a pickup truck. To watch the air flow to the radiator and around the hood we taped wool yarn all over the hood. Jomar drove the truck down the back roads near Roseau, while I hung out the window and filmed the yarn pattern as the wind blew over the hood. That was as close to a wind tunnel as you could get in Northern Minnesota in 1976.”
Bill did have dimensional restrictions based on the USSA race rule specifications associated with ski stance and width. Shoe-horning the 440 triple and its three expansion chambers under his new hood was not easy. Dalton Lisell had to fabricate the expansion chambers to just fit under the cowling. In some cases the hood had to be cut exposing sections of the pipes. The team abandoned using a motor mount and instead had the crankcase bolted directly to the bulkhead. The further reduced the CG and kept the motor more rigid. This also reduced clutch alignment issues, contributing to fewer blown belts.
Bill Clem would present the new IFS hood concept to Polaris top management. “Imagine a 19-year old presenting a new concept in snowmobile design to the President of Polaris. The group walked into the race shop and there next to JoMar Bernat’s toolbox was the Bill Clem hood design. It took maybe three (3) minutes and I was given the thumbs up.” In retrospect, the ‘77 RX-L race sleds are arguably one of the best-looking Polaris sleds of all time.
Fall 1976 – Time Flies When You’re Having Fun
Brad Hulings was just 20 years old and hired as a factory driver after his dominant season racing Mercury Sno-Twisters. Brad would learn real quickly that being a Polaris factory driver meant helping out & building your race sled with the fabricating team and sheets of aluminum. Brad said it best when I spoke with him about the people in the race dept; “I quickly realized that building these new race sleds was not just a job to them. This was their life!”
Greg Hedlund, Arlyn Saage, Dalton Lisell, Jim Bernat, Don Omdahl, Leroy Lindblad and Bob Eastman (among others) were the veterans in the race shop. Bunke, Hulings, JoMar Bernat, Steve Thorsen and Bill Clem were the kids.
Hulings recalled , “The group worked 7 days a week as many hours as you could. We traveled to Alaska in late October ‘76 and brought two conventional and two IFS sleds. The IFS sleds exceeded expectations.”
Arlyn got the call back at the race shop from Eastman, “Forget the conventional chassis, they’re yesterdays news.” Arlyn remembered that call well. “I hung the phone up and we started immediately on the third IFS chassis, with improvements. Brad said “In Alaska we broke a lot of parts, but also gained a crucial head start over the competition. We learned more about setup and where to strengthen the chassis. That was a big deal. Those first sleds were not crude by any means, but they not strong enough. We had a lot of work to do before the first race in Ironwood. In hindsight I am sure our competition thought we had made the wrong move.”
Winter of 77 – Keeping the Midnight Blue Express Running
The winter of ‘77 would go down as the best season on record for Polaris. The team finished 1-2-3 in the driver standings and claimed the World Championship. The team would not have IFS chassis sleds for all three drivers until late in the season. Greg Hedlund explains the routine the mechanics and support group would repeat for 12 race weekends in a row that winter. “Every night the 440 triples were re-ringed, the cranks checked with a dial indicator to make sure they were not bent. Jim Hedlund would straighten the cranks if need be. We tried to get zero to .004” run out. If they were not straight they had a high-speed harmonic vibration that would foam fuel in the carbs and create jetting issues. The pipes on the triples were not interchangeable. Each chassis was slightly different than the other.
The chassis and suspension parts initially were under-designed in many areas that were subjected to high lateral loading and stress. Arlyn Saage recalled, “That first race in Ironwood was the first time I saw them run on the track. The front end was such an improvement, the turning ability was huge. Through corner 1&2 there was not a lot of diffence after the start but into corner 3 it was like the other sleds stopped. After a couple of laps they would have a huge lead.
We set the IFS sleds so the springs were collapsed in the chassis so ski lift was minimal. Travel was a couple of inches. An IFS on a snowmobile does not have the luxury of a rubber tire absorbing some of the lateral loading when the vehicle is cornering. Racing a snowmobile at 100 mph into a left-hand corner results in high lateral and shock loading applied to the inside ski.”
The team quickly found out that the left side-trailing arm was cracking at the weld to the spindle and at the mount near your foot. “We kept reinforcing this area trying to beef it up,” Arlyn said. “I played around some with the height of rear trailing arm mount near your foot. If it were too low the load would not go into the chassis. This was important for body roll. We quickly were finding out the effects of camber and caster, torsion bar setting, spring rates and shock valving.”
Hulings, Thorsen and Jim Bernat all remember the first time they rode the new sled. “They were a dream to drive if the front end was setup right. We soon found out the skis had to be setup with just a slight toe-out. If they weren’t set well the bump steer was a problem. These things were right on the edge if not set properly. If you let off into a corner the front end would dive. You had to keep the power on to keep the pressure off the skis.”
Greg Hedlund (Hulings mechanic) explained the setup in more detail, “We lengthened the right side to push the left ski down. This allowed the inside ski to stay in contact with the snow. With IFS the carbides had to be sharp or they would push. The carbides had to have a rocker on them like a hockey skate. If they were straight and you hit a bump or the sled pitched forward and came down on the front of the ski it would pitch you right off the sled. Yamaha struggled with this. We changed the rocker so that 60% of the carbide was behind the spindle bolt and 40% to the front from the spindle bolt.”
The RXL Legacy – Better Control and Ride for the Masses
The shift from leaf spring (conventional chassis) to IFS was to increase cornering speeds and improve control on the racetrack. The ‘77 RXL raised the bar that season in these categories. The competition learned quickly and brought new suspension concepts to the track and trail. IFS ushered in a whole new generation of snowmobilers to the sport in the mid 80’s. It can also be argued that IFS was responsible for improving track suspensions to take advantage of longer travel front suspension and provide better balance between track and skis. The RXL came at just the right time for Polaris, as they quickly adapted the concept to the Indy trail performance model that is still synonymous with Polaris today.
It has been 41 years since those first RXL sleds hit the track. We salute the pioneers of the early trailing arm IFS (Bobby Unser, Gordon Rudolph and Gilles Villeneuve) and the team at Polaris Racing that were looking for chequered flags but won a bigger prize. Renewed interest in the sport. Where will the next breakthrough come from to once again kick start sales and renew interest?
By Hal Armstrong – SnowTech Canada
SnowTech would like to thank the following for their contribution to this story: Bob Eastman, Karolyn Eastman, Chuck Baxter, Bill Clem, Greg Hedlund, Jerry Shank, JoMar Bernat, Jim Bernat, Bob Aranson, Arlyn Sagge, Brad Hulings, Steve Thorsen and Larry Preston (author of Starfire Kids).
Photo credits:
Jim Beilke and Abby Johnson
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