Motorcycle Classics

Mystery MV: 1954 MV Agusta Idrobad Automatic

1954 MV Agusta Motoleggera Idrobad
Claimed power: 7.5hp @ 5,200 rpm
Top speed: 62mph (100kmh)
Engine: 172.3cc air-cooled OHC single, 62mm x 59.5mm bore and stroke, 6:1 compression ratio
Weight (wet): 227lb (103kg)
Fuel capacity/MPG: 3.7gal (14ltr)/55-65mpg (est.)

No more gears! No more clutch! This was what the prematurely printed brochure for the “automatic” MV Agusta 175 proclaimed. But the early promise was never fulfilled, and while the “greatest novelty in motorcycling” never went into production, one did survive.

It’s no exaggeration to say the MV Agusta Motoleggera 175cc “Idrobad” has to be one of the rarest motorcycles in the world. And it’s only thanks to MV enthusiast Dorian Skinner and the generosity and trust of the MV’s owner that it was able to see the light of day to be photographed, pored over, and ridden. It is a bike that was developed ahead of its time, but whose eventual production was canceled for reasons we can only guess at. Likely to be the only complete overhead cam MV Agusta 175 with cambio idraulico (hydraulic gearbox) in existence, it’s a motorcycle about which little is known.

Digging deeper

Sig. Sironi, the gatekeeper and historical expert of the MV Agusta Museum in Cascina Costa, Italy, knows of the bike but has never seen one, and reckons only a couple were even made; any records at MV are sparse. There is a mention in Mick Walker’s MV book along with a photo of a prototype — identical to this machine — that was displayed by MV Agusta at the 1954 Milan show, and it is extremely likely that it is the same bike: Even the battery looks to be the same one, still in place.

Apparently, the engine underwent some testing and assessment, and was even used in MV competition bikes competing with some success in the 250-mile Calanchi Trophy road race, as well as the Coppa Ducati regolarità. Another cambio idraulico MV 175 made its way to the U.K., where it was tested by MotorCycling magazine and featured in the Dec. 27, 1956 issue: Its fate is unknown, unless that bike is the one we have here in front of us, a connection that can’t be proved. There is supposedly an engine in Germany — and that’s it, nothing more remains. It seems the model attracted little enthusiasm.

What is so very special about this 4-stroke, overhead cam MV Agusta 175cc is its transmission, an infinitely variable drive unit that was developed by mechanical engineer Giovanni Badalini of Cambi Idraulici Badalini SPA, Rome. Badalini invented the drive unit for use in industry and engineering, and filed a patent with the United States Patent Office for a “rotary pump and motor hydraulic transmission” on Aug. 19, 1952, following up with further patent filings in November 21 and then again on May 12, 1953.

He appreciated that its compactness could lend itself to motorcycle application, and approached several manufacturers. MV Agusta was in a period of economic growth and very open to technological advances, so they were keen to use Badalini’s idea and perhaps steal a march on the opposition. To that end, Badalini filed yet another patent application with the U.S. Patent Office on July 12, 1954, that specified his design’s use as incorporated into a motorcycle engine.

One of the unique details of this bike is stamped onto the left engine case — Cambio Brev Idrobad, with “Idrobad” being a morphing of “Idro” (hydro) and “Bad” (Badalini). Looking at the right engine case, one notices the complete absence of a gear change lever. It’s a novelty that wouldn’t be repeated for another 20 years, until Honda built the CB750A automatic. The engine and the frame numbers are also stamped with unique “IDR” and “IDI” prefixes, and these tally with the bike’s original registration document, which very luckily has survived the years.

That document shows the Idrobad was first registered for the road in late September 1955, though its manufacture is declared as late 1954. In the intervening period, it was likely being used (and photographed, hence the shot in Mick Walker’s book) at events such as the 1954 Milan Show. Its current owner came across it purely by chance at the huge Imola mostra scambio swap meet in Northern Italy in the late 1980s, and saw at once that among the other MV 175s for sale it was subtly different. Even the Italians hadn’t noticed it. “Probably he had glanced at the unusual twist grip or the cables coming off the left handlebar,” Dorian says, “but he bought it there and then and brought it back to the U.K. It hasn’t turned a wheel since, until I serviced it the other week to prepare it for us to try. It’s in amazing, original and untouched condition, and happens to also run beautifully!”

The Badalini technology

It’s easy to call the Idrobad’s compact transmission unit an automatic, but it’s actually an infinitely variable drive, using engine oil as the drive medium via a hydraulic transmission unit that takes the place of a conventional clutch and gearbox. The Badalini unit operates at half engine speed from the standard 1:2 reduction primary-gear drive of the Agusta’s 175cc engine, and features a swash plate-type hydraulic pump and motor.

The pump and motor featured in the MV 175 both have seven cylinders contained in separate but co-axial bodies. These bodies are free to rotate independently, and the hydraulic fluid (which is the engine oil) flows from one set of cylinders to the other around a closed circuit and via a distributor valve. A non-rotating swash plate carried on trunnions actuates the motor pistons. A ram controls the angle of the tilt of the plate, controlled in turn by the left hand twist grip. A gear wheel carries an input “gearbox” shaft with the pump splined to it. This spindle from the pump forms the output shaft and carries the final drive sprocket for the chain final drive to the rear wheel. The pump and motor in the Badalini have no mechanical connection. As soon as the motor swash plate is inclined from its flat position, it causes the motor pistons to reciprocate and the motor then drives output.

The amount of oil supplied is determined by the swash plate, adjusted by the rider via cables attached to the twistgrip on the left hand bar. This twistgrip gives the rider manual control of the gear ratio. A lever on the left bar that looks like a standard clutch lever is actually a neutral lever, attached to the gear ratio control. Pulling on this lever actuates a tapered valve that allows hydraulic fluid to bypass the hydraulic motor completely. A small button on the lever mount holds the neutral lever in for starting purposes. Starting the MV is as normal. To move forward, you let the neutral lever out like a clutch, and you have drive. As the revs rise you twist the twistgrip — complete with the lever — forward, changing the gear ratio, and you go faster the more you accelerate with the throttle. Simple!

In practice

The idea is simple, the design is complicated, but in practice, it works well, especially considering the prototype nature of the MV and its age. Remember, this is a 1954 motorcycle. Dorian Skinner and I both took turns to experience riding the 175 Idrobad. It is very strange at first to be twisting a left hand grip to speed up or slow down, while also having nothing to do with your usual gear-shifting foot, but after a while it starts to make sense and functions reasonably smoothly, helped by the willing MV 175 engine.

A couple of testers in the 1950s mentioned that while the 175 was held in “neutral” they experienced creep from the engine, but at no time did I feel that the bike was pushing forward when not desired. Once I mastered the transmission, I discovered that the MV 175 is typical of any cammy Italian bike of that capacity and era — in other words, it wants to be revved and wants to run. Once on the move, the MV 175 is a pleasure to ride and control, despite the fact it sat unused for literally decades. The sound from the patina-soaked fishtail exhaust is fruity, sporty and very Italian. Everything else about the MV is familiar and functional. Its condition is wonderful — utterly untouched, and it’s no wonder its owner was so pleased to have found it.

“This MV is natural to ride to the point that you don’t even think about it, balancing the revs with a suitable gear ratio that the system runs at,” Dorian says. “When you come to a stop you don’t need to touch the lever. It’s much easier to ride than explain how it works!” He’s absolutely right, and it takes careful inspection of the technical drawings in the manual produced by MV at the time to get a basic grip on the technology and principles involved.

It’s likely that the standard CSTL 175 frame on which the Idrobad was based has been modified to accept the Idrobad’s larger crankcases, although from the cylinder upwards it’s the same as a standard CSTL 175. “It was a period that MV had plenty of money and was happy to experiment,” Dorian explains, “but despite putting together a brochure and adverts for this model, it never went into production. It’s likely that they had issues with the fact that the engine oil struggled to lubricate both the motor and hydraulic system at the same time. Maybe the oil of the time wasn’t advanced enough, and this oil issue killed the project. Maybe if they had designed the transmission and engine oil to run on separate oil feeds then all would have been good. The CSTL cammy motor was already marginal with the oil supply, so perhaps a 175 pushrod motor would have coped better, but it didn’t yet exist.”

It is easy to understand why this automatic system must have seemed like such an exciting idea to MV in 1953. But paradoxically, the Idrobad must have been simply too ahead of its time and not welcomed by conventional motorcyclists, who enjoyed and expected a standard manual clutch and gearbox. I can’t help being reminded of the Moto Guzzi Convert that also employed a hydraulic automatic transmission — a fantastic bike to ride but a sales flop for Guzzi.

After making some enquiries in Italy using the details on a copy of the original registration document, I discovered, amazingly, that this bike was actually sold new. You’d think that MV would have kept it as a prototype or testbed muletto for other experiments, but no, it was sold by an MV Agusta dealer, Pinotti of Pontremoli, in Tuscany, on September 21, 1955, to a certain Don Azeglio di Giuseppe Figaroli, who, it turns out, was a parish priest in Mulazzo, a mountainous district of Pontremoli! He owned the bike for nine years, selling it in December 1964 to a relative.

The special MV then disappeared into obscurity, until being rediscovered and brought to the U.K. For a priest, an automatic motorcycle would have been perfect — easy to ride, economic to run, and ideal for visiting needy parishioners in inaccessible areas. I have been in contact with a few elderly people from the area who remember what must have been a very unusual sight — a priest riding a motorcycle — but that’s as far as the story goes. I’m still on the case, and some day I hope to find a photo of Don Azeglio the priest sitting proudly on this unique MV — it must exist … somewhere. MC

  • Published on Oct 16, 2014
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