GP's Classic Steel #61: 1978 Husqvarna 390 Auto
By:
Tony Blazier

For this week’s GP’s Classic Steel we are going to take a look back at one of the most interesting bikes of the seventies, the 1978 Husqvarna 390 Auto.

In 1978, the most innovative machine in motocross did not come from Japan, it came from Sweden. The Husqvarna 390 Auto offered no shifter or manual clutch and did all the hard work for you. It was high tech, exotic and just a little bit too weird for the average motocross racers of the time.

In the auto industry, automatics make up 90% of the vehicles sold here in America. Everything from a mundane minivan to a rip snorting sports car can be had with the lowly slushbox.  While its convenience and ease-of-use benefits have been apparent from the very beginning, there is actually more to the automatic transmission than meets the eye. Today, the auto trans has come so far, that many performance cars do not even offer a fully manual gearbox. Even in the cars that do have both options, it is the auto that is often actually faster, executing precise shifts far quicker than any human can provide. With the advent of high tech SDC (Sequential Dual-Clutch) automated manuals and eight and nine speed autos, the days of the old fashioned manual clutch are numbered.

In the early nineties, Big Red took a stab at building a fully automatic racer of their own. It was raced in Japan and by all accounts, was very competitive. Even so, it never made it to production. Check out the crazy ATC style forward kickstarter!

Things are different in the two wheeled world, however. In motorcycling, manuals rule the day, relegating automatic transmissions to scooters and the assorted oddball Honda and Can-Am street bike. Even on a full boat Harley dresser, Billy Bob prefers to row his own gearbox. This is probably due to the whole involving experience motorcycle riders crave. We love the direct connection and intimate experience a motorcycle provides and shifting your own gears is part of that involvement.

The unique Husky Auto mill shared its top end with the garden variety 390 CR but mated it to a specially built automatic transmission. The transmission was a four-speed unit that used four centrifugal clutches to change ratios based on engine rpm and wheel speed.  The only real issue with its performance was its propensity to “free wheel” under deceleration. This alone made it a hard sell for many riders.

In the off-road world, autos are even rarer. While many ATV’s use CVT (Constant Variable Transmission) automatics, dirt bikes rarely see them. Aside from the Honda Cub and bizarre Rokon machines of the seventies, few dirt bikes have offered a fully automatic transmission. More common, is the “automatic clutch” manual transmission, which is often seen on entry level machines. This design uses traditional gears like most bikes, but mates it to a centrifugal clutch which disengages at low rpm and prevents stalling. This clutch is great for newbies that have not mastered the clutch, but terrible for performance and control.

These days, buying a Husqvarna means you are getting an Italian bike, financed by Germans. In 1978, however, buying a Husky meant Old World Swedish craftsmanship all the way. Husky was so confidant of the quality of their product that they backed every bike with a 60 day warranty and guaranteed the frames against breakage for life.

In the motocross world, the closest thing you will find today is the Rekluse auto clutch. The Rekluse operates on a similar theory to the old-school auto clutch, but adds the ability to modulate the power with a manual override when desired. Other than this cool aftermarket wizardry, the motocross auto is a bit of a pipe dream. Interestingly enough, however, this was not always the case.

Unlike the Japanese, who outsourced the suspension on their bikes, Husqvarna designed and built their own forks for the 390.  They were plush and well sorted out for the time, offering excellent performance. In ’78, the Swedes had the best forks in motocross.

Over the years, several manufacturers have played with the idea of producing a fully automatic motocrosser. Probably the most famous of these endeavors, was Honda’s early nineties flirtation with an automatic CR250. The bike was raced in Japan and by most accounts, was very promising. Jeff Stanton and JMB reportedly both rode the prototype and came away very impressed. Even with all the technical and financial might of Honda behind it, the automatic CR never made it past the prototype stage. Less well remembered, is a bike that actually took the automatic plunge a full fifteen years before the exotic Honda, the Husqvarna 360 Auto.

The rear of the 390 Auto was handled by a set of Gas Girlings shocks set up to Husky’s specifications. They offered ten inches of plush travel and were comparable to the best units available from Japan in ‘78.

Unlike today, where Husqvarna’s are oddball German-owned Italian motorcycles, seventies Huskies were 100% Swedish through and through. There were designed and built by Swedish craftsmen who took pride in building some of the best off-road motorcycles money could buy. They were at the forefront of the sixties two-stroke movement and a pioneer in the motocross and off-road explosion that took hold here in America soon after. In the early seventies, if you wanted a great off-road bike, you didn’t buy a Yamaha or Suzuki, you bought a Husky.

The 83mm x 71mm mill on the Husky displaced 384cc’s and pumped out 41 hp at 8000 rpm. This was more than competitive with the Open bikes of the day and combined with its broad torque curve gave the Husky one of the best Open class motors of ’78.

In the early seventies, Husqvarna was contracted to build bikes for the Swedish military with some interesting requirements. The Swedes wanted a bike that could be mastered by raw recruits in the shortest time possible, and in doing so requested Husky to design a fully automatic transmission. The Swedes, being a clever bunch, took to designing the simplest, lightest and most reliable automatic they could for the purposed military machines. The transmission would use a centrifugal clutch for initial engagement, and then a series of “dog clutches” to for the higher gears. It was a brilliantly simple and ruggedly reliable design that met the military’s requirements for ease of use and durability.

In the seventies, Husky was considered more than just an enduro bike manufacturer. Riders like Kent Howerton (pictured), Brad Lackey and Heikki Mikkola took the Swedish machines to several victories and titles in the middle part of the decade.

In 1976, the success of this military bike led Husky to trickle down this new technology to its production machines. The Husky 360 Auto was basically a standard 360 CR, mated to the all-new self-shifting gearbox. The top end and chassis were the same as the rest of the CR line, but the bike was expensive at $2395 and the performance was rather tepid. The original 360 motor was no powerhouse to begin with and the auto trans only magnified this deficiency. It was a cool bike, no doubt, but more of a curiosity than a conquering hero.

Rubber mounted bar mounts were standard on the Hooska and helped take bite out of the seventies era suspension.

After this initial attempt at a production autocrosser, Husqvarna went back to the drawing board for 1978. They upped the displacement to 384cc’s, spec’d a new chassis and bolted on a new set of long-travel suspenders. It was a thoroughly modern design, with a transmission to from the future. There was no denying it was trick, the only real question was-was it any good?

In truth, the answer was yes, with one caveat. In most respects, the Husky 390 Auto was the finest Open class motocross bike available in 1978.  In one area, though, it was a bit of an acquired taste. For starters, the Husky’s new 384cc mill pumped out a seamless flow of torque from top to bottom that was a perfect match to its slick auto trans. It was slower off the line than the other Open classers due to the slippery engagement of the clutch, but better at hooking up on slick surfaces. Once hooked up and in motion, though, the Husky was a match for anything else available at the time. Power was smooth, but strong and shifts were instantaneous under power. All you had to do was nail the throttle to the stops and hang on while that Star Wars tranny did the rest.

Originally, the ’78 the Husky’s came shod with Trelleborg tires mounted to Akront rims (Greg has obviously tossed these in favor of more modern Excel rims). This was actually considered a “premium” set up at the time. These days, Trelleborg is best known for its winter friendly studded ice tires.

While the power from the motor was strong and competitive, it was not without fault.  By far the oddest thing about the 390 AMX was the tranny’s propensity to “free-wheel” when the throttle was chopped. Under acceleration, the auto acted much like a normal motorcycle, with the four defined gears being selected by a combination of engine rpm and wheel speed. Where things got weird, was when you rolled off the power. Once you backed off the throttle, the clutch would disengage until power was reapplied. This meant a total lack of engine braking when decelerating, no minor inconvenience on an Open bike with mediocre drum brakes. This free-wheeling sensation was disconcerting to many riders and downright terrifying to others. Big down hills take on a whole new appearance when you can’t count on the motor to help keep your speed under control.

On the track, the Auto could be very effective, but it required a different riding style than other bikes. The complete lack of compression braking and absence of a clutch took some riders quite a while to adapt to.

The odd behavior of the transmission also manifested itself in the handling of the 390.  At the time, Husky was known for building some of the best handling chassis in the sport. They were stable at speed, while offering excellent cornering as well. Many an early Japanese chassis borrowed liberally from the Swedish designs. The ’78 390 Auto continued this tradition with what many considered to be the best Open class handling package of ‘78. It could rail the inside or blast the outside, berm or no berm, it did not matter. In the rough, the Swede tracked straight and true and as long as you kept the power on, did nothing funny.

The Leg Roaster.  The pass-through pipe on the Husky was known for peeling the flesh off of unfortunate victims during long motos. On the bright side, it was by far the quietest OEM system in ’78.

This last point was an important one, though. If you were power sliding, for instance, and you needed to back out of the power for a second, things could go terribly wrong, very quickly.  If you rolled off the power too suddenly and the tranny disengaged, it was a recipe for an instant high side. Jumps could also be tricky, as the lack of normal engine braking and weird on-off power engagement took a bit of getting used to. With the auto, it was important to be either under power or under breaking-anything else and the chassis would not take a proper set in the corners. With the proper technique, the Husky Auto handled flawlessly, if you forgot about its quirks; however, it could bite you.

Certainly one of the coolest Dirt Bike Magazine covers ever, Darth Vader had good taste in bikes in ’78. I find your lack of speed disturbing…

In addition to its stellar chassis manners, the Husky offered the best suspension performance of any Open classer in ’78. Its Husqvarna-built front forks punched out 9 ¼ inches of smooth action. They were plush, well damped and well set up for motocross use. 

None of that fancy pants synthetic junk here, Bro! Only “Vegetable Racing Oil” was good enough for the Swede.

In the rear, the Husky used a set of Gas Girlings shocks to handle the damping duties. The shocks were set up to the Swede’s specifications and offered nearly 10 inches of travel. They used a dual-rate, dual-spring arrangement to provide solid big bump absorption while maintaining terrain following articulation. In ’78, these were considered very good shocks and a match for the best Japan had to offer.

At $1995, the ’78 Husky 390 Auto was $400 more than its Japanese competition, but for that, you got Swedish quality, craftsmanship and exclusivity. If you could learn to live with its quirky nature, it was one of the best Open bikes available in ’78.

With a smooth and powerful motor, precise handling and the most solid suspension package on the track, the Husky 390 Auto had a lot going for it in’78. It was bike that offered a lot of performance, but also required a little different approach than your typical motocross machine. If you could learn to make the most of its advantages, it could get you to the checkered flag in a hurry. If, however, you forgot about its unique nature, it could just as easily put you on your head. It was an innovative idea that may have been before its time. If automatics do eventually come to the world of motocross (most likely, when electric powertrains become the norm), we may look back to these seventies Husky’s as forerunners to the bike of tomorrow.

 

 For your dailey dose of old-school moto goodness, make sure to follow me on Twitter-@TonyBlazier

Comments

Awesome!!

I have a 1985 Husky 500 Auto, and it's so freaking cool. It's definitely not a motocross bike; I don't think I would like to moto on an auto, but as a woods bike it is phenomenal.

Cool traits:

- Start it up, then let it idle down; it is in neutral. To put it in gear, you slide a little lever on the transmission from one position to the next. Now it's in gear; from this point forward, you twist the throttle and it goes.
- If you yank the front end up in a wheelie, it will shift by itself (obviously) and you can ride on the back wheel forever.
- Absolutely no engine braking; it completely freewheels when you let off the gas.
- It never stalls...never! The clutch disengages at low engine RPMs, thus making it impossible.
- You're always in the right gear for the conditions and speed you're going.
- It hooks up on the slickest stuff you can imagine - it excels in things like mud-covered roots, etc.
- You're basically riding a 500cc chainsaw when you think about it...

Cons:

- High maintenance; after every ride, you need to at LEAST filter the transmission fluid. The clutch drum and fingers need to be kept grooved to work properly (hacksaw does the trick).
- Speaking of transmission fluid, it takes a weird kind that you can't just run down to the automotive store and purchase.
- Clutch springs, especially first gear, can frequently break, and when they do you're stuck in second gear!
- The transmission gets REALLY hot.
- The kickstarter is on the left side; I've never quite mastered that yet, so I have to start the bike by standing on a milk crate on the left side (off the bike), and kicking with my right foot like normal. It looks a bit weird, actually.
- Because the engine has to idle down prior to putting the bike in gear, you get absolutely creamed on dead-engine hare scramble starts. I sure did when I raced it in one a few years ago - last off the line, to be exact.
- It vibrates so bad. I mean....so bad. The rear fender is a blur when it's idling it's so bad.
- If you can't get it to start by kicking it for whatever reason, you're pretty much out of luck, as you can't roll down a hill (or get towed by somebody) and bump-start it - no clutch to "pop" and no way to put it in gear while you're rolling.
- Getting harder to find parts!

It's such a cool bike and it definitely gets people's attention once they realize what it is they're looking at and listening to...a guy riding a Husky Auto sounds like nothing else out there; a continuous, smooth sound lacking the typical engine revs and clutching sounds that you're used to.

If you ever get the chance to ride one; TAKE IT! Every single person I've let ride it has come back and asked to ride it again just to experience it one more time.

1978 390 Auto.... trans fix....

i owned a '78 auto, bought new in '78.... raced it for two years,
sold it, and bought the same bike back a second time, from a
different party than i sold it to..... they are addictive.

i'm quite sure it was also the only 390 auto with California plates on it,
but that's another story.

it had one fatal flaw.... it would break the starter sprague at random intervals...
like halfway thru the second loop out near ridgecrest... it got so bad that i carried
a spare sprague in the tool kit, and could change it in about 20 minutes. on the trail.

and... i found the problem, and a fix for it... if any of you have one of these, this might
come in handy to know. those of you with experience with this, know that you don't
know it has failed until you shut off, and can't start it, as there is no way to spin the
engine over.

here is why the starter sprague breaks:

sometimes when you shut off the engine, the transmission will make a little sound
like a turbo spinning down, sounds kinda cool.... what is happening, is the engine
is coming up on top dead center, and doesn't have enough inertia to go over top,
and kicks backwards, opening the ports, and coming to a stop. no big deal, until
you realize that sound is the engine kicking back thru the start sprague, and
SPINNING THE ENTIRE TRANSMISSION CLUTCH PACK BACKWARDS.

that is why the sprague fails. the impact is not something it's designed to absorb,
and it breaks the lips off on the "dogbones" segments of the sprague, causing it
to die.

here is the fix:

remove the kill button. throw it away
remove the head.
take the head to a machine shop, have a second spark plug hole machined in the head.
install a compression release.
put the head back on.

now, always kill the engine with the compression release, and you'll never break a sprague again.

and if anyone knows of one of these for sale, i'd REALLY like to know about it.

like they say, third times a charm.