Timeline: 1973 John Deere JDX Snowmobile
When Deere and Company began developing a snow machine in 1969, it joined many others by copying market-leader Bombardier’s successful layout with the engine atop a welded steel tunnel and bogie wheels underneath. Introduced for the 1972 model year, the initial John Deere snowmobiles were well-built and reliable, but hamstrung by the inherent ride and handling limitations of Bombardier’s now outdated concept.
The market was moving toward better performance, so Deere again followed many other brands by adapting the outmoded template for its new JDX series. Two versions were available for 1973: the top-of-the-line JDX 8 with a CCW 440 engine and a Salisbury 850 drive clutch; and the JDX 4 with a Kohler 292, a Salsbury 780 drive clutch and a bit less standard equipment.
Performer or Pretender?
As the new flagship of the line, the JDX series was promoted in John Deere sales literature as having “superior performance and distinctive styling.” Superlatives were flung around like macaroni salad in a food fight, always a good indication of a bunch of baloney. “From ski tip to snow flap, the JDX 8 is a totally new sled,” read the brochure. “The ultra-low silhouette, bold ‘blitz-black’ color, and unique trim treatment suggest eager speed and agile handling.”
But observation of the ‘73 Deere spec sheets and new model photos would lead you to believe that there was no difference between the carryover Model 500 green machine and the JDX models except for color, a lower windshield and ski shocks on the new additions to the line.
Actually that wasn’t quite correct because the JDX 8 did get a similar but completely different engine. A 438cc CCW KEC 440/21 motor replaced the 436cc CCW KEC 440/4 powerplant of the Model 500. Bore and stoke were slightly different, the 438 got a slightly bigger carb, and the final gearing was changed. Rated at 38 to 40 horsepower (depending on SAE test method) instead of the 36 hp engine in the Model 500, the slightly hotter engine helped justify a $100 price premium for the JDX 8 over the green machine.
But with the old style chassis and bogie wheels, this was a very tame ride compared to the new 55 hp Arctic Cat El Tigré 400 and 440, or any other of the emerging free air Stock racers. Even worse, many directly competitive fan-cooled machines, like the lighter weight 46-horsepower Chaparral SS/III 440, the 44-horse Northway Interceptor 440 and the racy red Rupp Nitro 440, had the power and the handling to blow the JDX into the weeds. Plus, all these competitive machines had slide rail suspensions and disc brakes, and most had Capacitor Discharge ignitions, too.
Performance-oriented sled magazines largely ignored the new JDX series. But Invitation To Snowmobiling tested JDX 8 and had some unusually candid observations. They called it “sporty but not overly quick,” noting that it finished next to last among seven machines in their time trials. And although ride quality was rated slightly above average, the review noted that one editor was thrown off the sled by an unexpected bump while side-hilling. Worse, with the second highest center-of-gravity of all 21 machines tested, the JDX 8 was anything but stable. Testers said it was agile, but also called it “touchy” and “demanding” in the turns despite the standard carbide runners. The archaic 4.25-inch external band brake with the drum on the secondary shaft wasn’t impressive, either. “The JDX was next to last in stopping distance of the eight machines tested,” the publication reported.
On the plus side, the magazine found the JDX 8 to be the second quietest sled among the 21 tested that spring. They lauded the flip-up hood panel for easy refueling and the safety spill tray atop the steel gas tank. Other positive comments covered numerous additional safety features and service provisions including an under-hood trouble shooting decal and Deere’s excellent dealer service.
But in the end, Invitation To Snowmobiling went on record with a rather negative summation. “The machine offers distinctive styling and, in some areas, superior performance. However, we can’t give it a top-grade rating because balancing the JDX on uneven terrain or whirling through tight turns with it demands inordinate skill.”
The maladroit JDX series hung around for a couple more years with some upgrades to areas like clutching, and with yet another model, the seldom seen 399cc JDX 6. But even financing with deferred payments and deferred interest plus a free snowmobile suit with the sled couldn’t make the JDX series a winner on the sales floor.
The lesson was obvious. A black paint job, a short windshield and a couple extra horsepower just did not make a performance sled. The JDX was obsolete at introduction and doomed to failure no matter how well Deere executed and promoted the out-dated design.
But unlike several of their snowmobile competitors, Deere and Company would not repeat this mistake with its next consumer performance sled. The 1976 Liquifire was a thoroughly modern machine that could hold its own against the best from the rest of the industry.
1973 John Deere JDX 8
Manufacturer: Deere & Company, Horicon, Wisconsin
Engine: 438cc Kioritz/Canadian Curtis Wright KEC 440/21 axial-fan-cooled case-reed twin with one Walbro WDA-34 diaphragm pumper carb and a single exhaust.
Ignition: Magneto and breaker points
Power Output: 40 hp @ 6,750 RPM
Clutches: Salsbury 850 drive and John Deere driven
Chassis: Painted aluminum tunnel & belly pan with chromed steel bumpers and fiberglass hood
Dry Weight (claimed): 386 pounds
Front Suspension: Triple-leaf springs with hydraulic shock absorbers
Rear Suspension: Trailing arm bogie type, with 15 polyurethane wheels on 6 trucks
Ski Stance: 28-inches
Track: 15.5- by 118-inch steel-reinforced molded polyurethane;
Brake: External band drum type
This article first appeared in the October 2013 issue of Snow Goer magazine. To subscribe to Snow Goer, click here.