Long before the Indy, XCR, Pro-X or RUSH the name that was synonymous with Polaris performance snowmobiles was the TX.
The Polaris TX had been a world-beater on the racetracks until the 1974 season when the production version of the TX started to show its age. The introduction of the Mercury Snow Twister, Arctic Cat Z, Yamaha GPX and the Ski-Doo TNT F/A (which were more race track oriented rather than all-purpose trail performance sleds) quickly put the TX into the last chance qualifiers. The drought continued into 1975 with the same basic chassis/suspension combo with Bold New Graphics, but in reality not many Polaris TX sleds were found in the pits.
The SnoPro factory circuit was another story. Polaris dominated the premier race series in ‘74 and ‘75 with a completely new chassis that was to be the forerunner of the ‘76 TX production sleds. When the 1976 TX was introduced, the Polaris faithful could not wait to get their hands on one of these SnoPro knock-offs. The ‘76 TX was a complete departure from any model Polaris had built for the consumer. The next-generation TX featured new free air engines, a jackshaft mounted secondary clutch, aluminum slide rail suspension, lower cg and it retained the styling from those sexy looking factory modified race sleds.
Polaris took the TX one step further and offered a limited build TX Starfire oval race sled for the stock racing wars. The chassis was on par with the competition and the free air engines could run with the competitor’s liquid cooled motors when the air temperature was well below zero. When the weather was milder the consistent engine temperature provided by liquid cooling allowed the competition to pull away from the new Polaris.
On the SnoPro circuit, Polaris was busy evaluating new liquid cooled Fuji engines. What many did not know was that Polaris offered a liquid cooling kit to convert the 340 free air engine to a water jacket. It was not a project for the backyard mechanic to install, but the factory race team competed with LQ engines for the first time that winter.
On the cross country circuit the Winnipeg to St. Paul I-500 was claimed by John Deere with a new liquid cooled powered Liquidator. This did not sit lightly with the brain trust in Roseau. To get beat in your own backyard was a wake up call! By mid-February the Test Engineering Group would be racing two thinly disguised liquid cooled 340cc TX Starfire’s in the 340 modified class with success. Clearly a cross-country version of the TX would need to be readied for the ‘77 season.
The free air engine chapter in snowmobile history was beginning to wind down after the ‘76 season. All the manufacturers now were focused on designing new engines and cooling systems that were going to be used in the next wave of consumer snowmobiles.
The TX-L was built up on the ‘76 TX chassis but with significant changes to compete on the cross-country race circuit. The ‘77 model would introduce a significant number of features that would be used in future Polaris models for years to come.
Polaris engineering, working with their exclusive engine supplier at the time (Fuji Heavy Industries), designed a mono block design that would later be used on the Indy 400, Indy 500 and XCR 440 models. The 333cc piston-port engine produced 56 hp thanks to an upgrade to 38mm Mikuni round slide carbs and tuned exhaust with resonator to meet sound regulations. While 56 hp does not seem like much today, back in 1977 having a 340cc stock motor produce over 50 hp was unheard of. A few years earlier the 500cc triple free air from Polaris was the horsepower king with 50 hp.
The cooling system was unique to Polaris and patented. When first introduced, the running board cooling extrusions were met with skepticism. I remember being at the first snowmobile show in Duluth, Minnesota in the fall of ‘76 where everyone was shaking their heads looking at this new system for the first time. The coolers were thought to be too vulnerable to rocks, stumps or for that matter even tipping the sled on its side to work on. We were all proven wrong. The cooling system was simple and efficient. Snow kicked up from the rear of the skis cooled the running board extrusions and in low snow conditions slush and water kicked up from the skis were just as efficient for cooling.
This design also stiffened the running boards so they did not bend when making hard landings and they also kept your feet warm! Another unique feature of the cooling system was that all the coolant plumbing was located inside the engine compartment, well protected. Polaris stuck with this design for more than twenty years, and many of us wish they would bring it back!
The drive train was amazingly very similar to current production Polaris sleds. Efficient Polaris clutching was the magic that made the most of delivering engine power to the track and hydraulic disc brakes brought it all to a stop. In straight line acceleration runs the little 340 would often embarrass larger 440s simply because of the clutching getting more power down to the track.
While the liquid cooled engine was making the headlines it was where all that power met the trail that was equally newsworthy. A new rubber track was wrapped around an all-new dual shock aluminum skidframe. Polaris Engineering had made the break from the classic steel cleated track to improve reliability, reduce rotating mass and extended the track length to improve ride and straight line stability in the rough (sound familiar?).
Cross Country racing is like taking trail riding to the extreme. The late 1970s was just the birth of organized trail systems that we all enjoy today. Grooming activities were miniscule compared to today, so you know what that means. A late Sunday afternoon trail condition today was a good day back then. So what did the TX-L offer to smooth all those moguls and bumps? The new rear suspension was simple compared to what we enjoy today. Dual non-rebuildable shocks dampened the rear arm while the front torque arm used torsion springs but was not dampened. The suspension had five adjustments to control weight transfer and spring load. The spring rate on the four torsion springs was calibrated to prevent bottoming. Think of today’s Snocross sleds. Trail riders that bought this sled soon found out that the ride left something to be desired. Total travel for this state of the art terrain racer? A whopping four inches.
Up front, attention to ski suspension technology had evolved to a single leaf spring and a hydraulic shock replacing the triple leaf spring used on earlier TX sleds. Steel skis with carbides were still the norm. It was would be three more years before Independent Front Suspension (IFS) would appear on the trail. IFS was just in its infancy and development was targeted for the oval track wars.
The Race Results
Factory XC teams from Arctic Cat, Ski-Doo, Yamaha, John Deere and Scorpion met the Polaris riders in force all season long. Every manufacturer built special build sleds for Cross Country. CC was taken seriously in the late 70’s, much as SnoX has been recently. In fact, we are starting to see a resurgence in cross country interest once again.
The ICCSF sanctioning body had put together an eleven (11) race schedule plus the prized jewel, the Winnipeg to St. Paul I-500. Heading into the I-500, five (5) races had been completed and Polaris had won two (2) and Cat, Ski-Doo and John Deere had each claimed a win. The I-500 always ran the third week in January. The ‘77 race ran in reverse from St. Paul Minnesota to Winnipeg, Manitoba. At the start line on Day 1, 320 riders lined up. The first leg was 179 miles and just 50% of the riders completed it. Day 2 had only 118 complete the run. The third day had just 90 riders lined up in Thief River Falls, MN (home of Arctic Cat). The race was called when high winds created near blizzard conditions reducing visibility to zero. Polaris rider Archie Simonson (just 18 years old) won the race with TX-L sleds taking 9 of the 10 top spots.
The remainder of the season would see all the manufactures trade victories. Polaris left the ‘77 season with it improving its position in the terrain wars. Polaris sleds won 5 of the 12 races but there was more work to do going forward.
More Work to Do
The 1977 TX-L was the snowmobile that Polaris used to begin the transisiton from free air engines to liquid cooling and steel cleated tracks to rubber. Racing does improve the breed and as the ‘77 season closed the snowmobile industry was again entering a transition time. The success of IFS on the oval track was already begging the question of not if, but when the new ski suspension would appear on a XC sled. Liquid cooling was still in its infancy as the complexities of cooling the engine without increasing weight was still under development.
At Polaris the TX-L would serve as the platform that would introduce the first modern long travel rear suspension in 1979 and father the transition to IFS with the 1980 TX-L Indy. Exciting times were ahead!
By Hal Armstrong – SnowTech Canada (Originally published in the January/February 2013 issue of SnowTech Magazine)
Photo credits: Jim Beilke (SnowTech Magazine), and AJ Emrick
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