1975 John Deere JDX-8 440

John Deere’s top of the line 440 looked like quite a top performer after all 13 of SNOW GOER’s mechanical tests on top of Rabbit Ear s Pass. All but one, that is.

Consider this.

The JDX-8 zipped through the ¼-mile acceleration run in 19.7 seconds and ate up the ½-mile course in 12.2 seconds, for third and fourth place finishes. Top speed in the snow was 61 mph, well above average. On the dyno, Deere continued its quality showing, hitting 70.8 mph under no load for a fifth place finish and capturing second place in top speed under a loaded condition equivalent to 5 inches of powder snow with 57 mph, besting the average by 6.5 mph. On the dyno, the JDX-8 also clicked off 0 to 60 in 11.4 seconds to grab second in that class, too. The’ Deere dropped to third in delivered horsepower to the track with 28, only two hp off the winner.

Then the JDX-8 took on the drawbar pull, muscling 325 pounds to return to its second place status, and at the same time losing only 500 rpm on backshift, bettering the average of the 440 fans there.

Top performers normally don’t get good gas mileage, but in an 8-mile economy run the JDX-8 came in with 18.2 mpg, good enough for anyone’s trail ride. Still not satisfied, the muscular 440 swept the quiet sweepstakes, producing only 72.2 db(A) at 50 feet.

But even Achilles had a heel and so did the JDX-8 we rode at Rabbit Ear’s.

This was our third year of testing powerful 440’s from this farm implement company that has made quite a niche in the snowmobile industry. We had grown used to certain things. Like snappy acceleration, above average top speed, quality engineering, comfortable and workable seat and suspension. We’ve never been disappointed in these things and we weren’t disappointed this year. But it does have a stability and steering problem. How do you harness that powertrain and keep control in hands of the driver?

While everything else performs well the snow, what’s out of character is JDX-8’s instability at high speeds or over rough, moguled trails. Last year’s JDX while not as powerful, provided comforting stability and sure, easy steering control. No major changes were made in JDX-8 for ‘75, but stability was definitely affected. Over 16 pounds, not counting the weight of gas in either model, was shaved off last year’s sled. Monoleaf suspension replaces last year’s multileaf. Position of piston-shaped ski shocks was changed to mount directly over the ski leg. But, someplace between the ‘74 JDX-8 and the ‘75 version, Deere lost 6.5 degrees in stability, from 41 last year to 34.5 and 36 degrees left and right this year, and an intangible—driver confidence in his ability to control the sled at high speeds.

Knowing Deere’s commitment to the snowmobile industry ($10 million plant expansion, an expanded seven model lineup for ‘75, plus a high performance 340S) and the high caliber of their engineering department, this flaw in the ‘75 JDX-8 will probably be corrected by the time you read this. It would be worth a test ride to find out.

If Deere engineers can recapture the stability of previous years, the JDX-8 will be a super quality snowmobile. Everything else is there and it’s right on.

Its Kiorjtz 438cc reed valve engine, With an expansion chamber that works like a turbocharger and adds six horsepower, gives steady, strong performance and sudden acceleration anytime you want to hit the throttle from o to 50 mph.

As indicated by the 325 pounds draw- bar pull and 28 delivered horsepower (over 62 per cent of the rated hp), Deere’s Comet clutch provides steady torque to the track. The fully-adjustable weight-transfer slide rail suspension and bottomless seat give first class comfort. The unique suspension transfers weight to the back for better traction and lifts weight from the skis during acceleration, then levels the track for cruising. Twin shocks and adjustable springs take the jolts out of sudden moguls.

The 15-inch grouser bar track has the characteristics of a wide-track, giving biting, steady traction on both the flats and the mountains.

The hot 440 also contains its share of engineering conveniences.

Improvements under the hood include a high-density polyethylene fuel tank with a 6.5 gallon capacity. A new external band brake with improved mounting provides quicker stops and longer wear.

Looks of the JDX-8 have also been streamlined. Blitz-black with silver trim, the new hood design gives a symmetrical front styling with the center headlight flanked by air intake louvers on one side, and the easy access fuel tank panel on the other

Other standard bonuses include speedometer, tach, carbide wear rods, 120-watt electrical system, a high windshield that gives better protection, plus a heat barrier to protect the carb from vapor lock.

The JDX-8’s are sturdy machines, engineered and built to last, and, there’s full year warranty on all parts and labor Plus, Deere is introducing a new track replacement policy to better protect the consumer and keep him on the trail. If the track failure occurs within the first 12 months and is not covered by warranty due to operator error, the track will replaced at 60 percent of the cost. If the track failure occurs within the second 12 months, a 25 percent discount will given.

The JDX-8 is a top quality machine possessed by a tipsy demon for inexperienced riders. If the exorcist gets ahold of it before you do, you’ll find quite a sled waiting for you.

Manufacturer: John Deere Consumer Products, Horicon, Wisc. 53032.

Suggested Price: $1,650.00.


Engine: Kioritz reed valve 438cc twin.

Clutch Comet.

Carburetor: Walbro.

Dimensions: Height, 40.5-in. Width, 34.7-in.

Length, 103.4-in.

Chassis: Aluminum.

Track: Rubber with molded in grouser bar.

Suspension: Slide rail.

Brake: External band.

Fuel Tank: 6.5 gallon capacity.

Weight: 447.5 lbs. wet; 406.5 lbs. dry.


Location: Rabbit Ear’s Pass, Colorado.

Test Conditions: 4 foot base spring snow.

Altitude: 9,426 feet

Top Speed On Snow, mph: 61.

Acceleration 1/a-mile, sec: 12.2.

Acceleration 1/4-mile, se 19.7.

Gasolina Economy, mpg: 18.2.

Overturn Angle Left, degrees: 345.

Overturn Angle Right, degrees: 36.

Noise, at 50 ft.: 72.2 db(A).

Drawbar Pull On Dyno, pounds: 325,

RPM Loss On Backshift: 500.

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