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Swoosh and screech! The rise and fall of alternative power in motor racing
Part 2: The perfect gear

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CVTs: the pros and cons

Some say the perfect engine is the engine with optimal performance at every possible speed. Lately, car manufacturers with a tradition in engine wizardry, such as Honda and BMW, have tried achieve this using the ingenious VTEC variable camshaft and valve timing system or the even more complex Geartronic system. But all these systems are approximations of the theoretic advantage that continuously variable transmissions (CVTs) have. So why didn't CVTs become de rigueur in racing? The answer to that is two-fold: at first, the CVT principle proved unworkable with big sporty engines. And when a quarter of a century later its inventor, Van Doorne's Transmissie, finally succeeded to create a bomb-proof CVT that could stick it out in the back of a Grand Prix car, it was banned.

The workings of a Variomatic transmission are a bit of a mystery to most. Yet its concept is surprisingly simple. Let's take some time to take you through the motions.

You need three basic elements: two pulleys, a belt and a small box of fixed gears. Why fixed gears? Instead of the gearbox changing gear ratios, the V-belt on the pulleys that expand and contract depending on the engine speed and load determines the perfect ratio at all speeds. The gears are simply used to transfer power to the axle.

So how do these pulleys work together? The first pulley is also known as the variator, and in fact consists of two half pulleys, of which one is moveable, while the other is fixed. The fixed half pulley is bolted to the crankshaft, while the belt runs on the moveable half pulley. The belt - used to transfer power from the crank to the rear pulley - is held in a position perfect for every speed by a specially cast or machined ramp that shift roller weights up and down a carefully calculated arc. This conical wheel works to keep to the engine revving in its sweet spot, where it delivers its peak power. The roller weights act against the drive belt, moving it up or down the ramp. In this way, the variator could be seen as the car's gearbox, as it acts as the mediator between the engine's speed and the rear wheels' speed.

The belt in turn drives the rear pulley that is connected to a centrifugal clutch. They are forced together by a torque spring. Both are also rotating on the same input shaft to a small fixed-ratio gearbox used to reduce the clutch's high rpm to revs that are suitable for the rear wheels.

There is much importance in the correct weight of the rollers, as they are pushed up the moveable pulley's arc by the centrifugal force instigated by the crankshaft. If the rollers are too light, the engine would be overrevving - like staying in first gear when you should have changed up and feel that the engine's power is tailing off. On the other hand, rollers that are too heavy will lead to sluggish engine performance, as it won't reach peak power.

But get it right, and the rewards are masterful. Although the CVT concept barely survives in modern road car manufacturing - Audi is the only currently supplying a CVT-equipped model - people who have driven DAFs in the past, or still do, are raving about the auto transmission's ease-of-use, stating that manual shifts are cumbersome compared to the true Variomatic experience…

CVTs: the ancestry and the heritage

The CVT was invented in the Netherlands, in a factory led by brothers Hub and Wim van Doorne. Hub was the duo's tech buff, while Wim shared their business brain. Although their "Variomatic", as the CVT was commercially known, was to become their most famous accomplishment, their history goes back much longer.

Hub and Wim were the sons of a blacksmith, so they had a genetic imprint for technology. Especially Hub, ominously born on January 1, 1900, was to have a independent technical mind, spurred on by the death of his father in 1911, and the resulting obligation to go his own way as an 11-year-old. In his twenties he came good to become chief mechanic at Jos Mandigers before deciding to start his own business in 1928, "Hub van Doorne's Machinefabriek" (machine factory), on a loan furnished by a befriended Brabant brewer. Soon he persuaded brother Wim to join the company. Wim's business acumen was a great match for Hub's technical vision, and while many companies faltered or succumbed during the hardship of the thirties, the Van Doorne brothers managed to grow their business by their first new invention: the lightweight trailer. For this, another company, "Van Doorne's Aanhangwagen Fabriek" (trailer factory), was founded in 1932, and the acronym DAF was born. After their lightweight trailer the "DAF-losser" (a brilliant train-to-truck container moving system) and the "Trado-stel" (a clever tandem unit for quick offroad conversion of regular trucks) were introduced. With war beckoning, the latter product quickly found its way into the army.

In war time the Germans occupied the DAF factory, but Hub and Wim secretly worked on a host of new inventions, which were put into practice as soon as war ended, including the DAF tanker - a three-minute aeroplane refuelling system. In 1949, DAF decided on to embark on lorry production, with the meaning of the DAF acronym now changed to "Van Doorne's Automobiel Fabriek". The army remained a loyal customer.

Four years later, the brothers took their biggest decision yet: they were to start a car production line. Their initial plans included a small two-stroke engined scooter car à la Isetta and Messerschmidt. But at the Amsterdam car exhibition of 1958 DAF surprised the world with the 600, or “A-type”, a full-size car equipped with a four-stroke, air-cooled, 2-cylinder boxer engine and a quaint transmission system called Variomatic. It was still a people’s car, though. And the people loved it – over 4,000 cars were sold at the exhibition alone, forcing DAF to completely overhaul their production scheme, as they hadn’t been expecting this sort of numbers.

After a slow start to production DAF got on with the job of introducing new models and engines. In 1962 the 600 was succeeded by the 750, nicknamed the "Daffodil", and sported an enlarged engine to 746cc, which produced a whopping top speed of 95 kph. So you couldn't even break the speed limit if you wanted to! Later renamed 32/33 (the 33 had a slightly more potent engine), this car stayed in production until 1975, DAF's final year as an independent manufacturer. At this time it was decided to improve and sell the technology through rallying and racing. DAF became famous in the Netherlands but internationally the Variomatic never really caught on. Perhaps the “silly little car” looks of the DAF were to blame – these weren’t compatible with the delusions of grandeur that most German, French, British and Italian customers were getting used to with the latest products of their local manufacturers. Moreover, the customers who liked the user-friendliness of the DAF were usually elderly people that reacted as fast in traffic as the DAF’s 0-60 acceleration time – slow... Who would want to be accused of being part of that particular group of drivers?

On the height of its motorsport activities DAF launched two new models. The 44 – a Michelotto design – was introduced in 1966 and had a longer wheelbase, increased by 170mm. Its air-cooled engine was bored out further to 844cc, giving a top speed of 110 kph. It was also available as an estate, and as a van, and in this guise it was a popular choice among small retailers that used the car on their delivery rounds. Two years later the snappy 55 saw the light, in sedan, estate and coupé versions. The air-cooled 2-cylinder was replaced with a water-cooled Renault Gordini 1.1-litre four-cylinder, allowing for a top speed of 130 kph, while the chassis at the front was beefed up with McPherson struts and disc brakes. In 1972 the 55 was replaced by the 66, which after 1975 continued as the Volvo 66. It used a De Dion rear axle, which improved the handling, but the car kept the traditional boring DAF shape. The biggest embarrassment was the re-introduction of the 44, rechristened 46, an unashamed attempt by Volvo to clear out the remaining stock.

So up until the moment DAF decided to sell off their car division to Volvo in 1975, the "600" in all its various guises remained the lynchpin of the model line-up. DAF never managed to introduce a more serious looking motor car. The sell effectively killed off the Variomatic, although Volvo kept it going for a while in their Dutch-developed 340 model - effectively the fourth-generation DAF with a Swedish badge. Business-wise, however, it was a smart decision by the Van Doornes to continue with truck production. The NedCar production site at Born remained a vital element in Volvo’s strategy, with the 440/460/480 and later the S40/V40 families designed and manufactured there. Today, NedCar is a joint-venture between Volvo and Mitsubishi: the factory also produces the Carisma and the Space Star.

Even after his official retirement, Hub van Doorne remained involved at Van Doorne’s Transmissie (VDT) in Tilburg, which continued to develop the CVT as an independent technology firm. After their abortive CVT project with the Williams F1 team, VDT introduced the Transmatic to late-nineties road cars such as the Ford Escort Zetec and the Nissan Primera.

Today, CVTs primarily live on in scooter bikes, while only a couple of car manufacturers offer CVT. Nissan carry on the CVT that started with the Micra in 1992, with their latest Almera Tino people carrier also sporting a CVT version. BMW have moved into the CVT frame as well by offering their Mini with a Steptronic CVT. Audi is the most prominent among today's CVT users with its self-developed Multitronic system. Ironically, it is found in the bigger A4 and A6 models, with chains having replaced the belts to increase the amount of torque it can handle, and it is sold as an exclusive luxury option. Quite the opposite of what the Van Doornes originally set out to do, and precisely the route they should have pursued further in an effort to help DAF survive as an independent Dutch car manufacturer. After all, they didn’t enter racing for nothing.

Still, the dream of creating the perfect gearbox lives on in the minds of VDT and other companies as well, such as Torotrak, a Rover/Leyland/Lucas spin-off that is developing a toroidal disc-based Infinitely Variable Transmission for road-car use and has found Ford as its first licensed manufacturer.

CVTs: the cars and the stars

The decision to create a people's car around the Variomatic was part of Van Doorne's vision. But there was a practical reason too. The CVT system wasn't capable of handling huge amounts of power, thereby restricting DAF to small, tatty cars, with no chance of adding a more powerful image builder to their programme.

Formula 3

So in 1963 DAF's R&D department, led by Henk van Zalinge, decided to focus on developing a Variomatic that would sustain the strain of a powerful engine. Van Zalinge soon discovered that a racing chassis and engine would provide the best possible testing bed, and for this DAF acquired an uncomplicated Cosworth-engined Alexis F3 car. DAF's CVT wizard Wim Hendriks successfully adapted the Variomatic transmission to the 1.1-litre BDA engine. It first ran in November 1963, at Welschap airport near the factory’s homebase of Eindhoven.

In 1964, this sparked off the decision to form a racing department: DAF Racing Team. Rob Koch was asked to lead it while none other than Rob Slotemaker, who had done some rallying for DAF up until that point, was contracted to test the Alexis-DAF Mk5 at nearby Zolder. Zolder also saw the car's debut, but Slotemaker was a non-starter due to a fuel feed problem unrelated to the Variomatic. Then DAF entered Rob for the prestigious Monaco F3 race. Here, Slotemaker managed 11th on the grid and ran out the race in 7th, a respectable result for what amounted to nothing more than a test hack.

Later that year Koch met Jack Brabham and went on to convince him of delivering and co-developing a pair of Variomatic-powered Brabham F3 chassis. Black Jack, being among the most technically minded drivers of his time and largely responsible for guiding Cooper towards the rear-engined route that changed Grand Prix racing forever, showed an immediate interest.

Brabham had become a constructor in 1964 and saw the cooperation with DAF as a new challenge. Teaming up with Ron Tauranac, he rapidly expanded his company to supply a wealth of customer chassis for almost every type of single-seater racing. Jack used his technical savvy to turn the car into a reliable proposition, a job he mastered to the extreme as was shown that Grand Prix season by the Brabham-Repco F1 car, that Jack's calm and collected outfit used to race towards a pair of World Championships untroubled by car niggles and in-team fighting.

In August ’65 the first "Brabham-DAF" was entered in the Zandvoort F3 race and Slotemaker ran reliably to the finish in 8th. In 1966 DAF and Brabham teamed up with British F3 team The Chequered Flag to field their effort. The team contracted Mike Beckwith to race the Brabham-DAF BT18A. As with the Alexis, the Cosworth engine (now a 1.6-litre MAE) was tuned to top power, with the Variomatic taking care of the necessary flexibility. The team took part in 16 races all over the continent. In a season in which Piers Courage and Chris Irwin swapped wins, with Jonathan Williams and Roy Pike co-starring, Beckwith's best results came in the Lotteria GP at Monza (second place) and in the late-summer Leston Trophy at Brands (third). Many pundits thought this was turning into a very interesting development. The car showed several weak points, however. The aero efficiency was dreadful, with the Variomatic taking up lots of space in the back, while the exposed rubber belts were a big problem during wet races.

The following season The Chequered Flag hired Gijs van Lennep to partner Beckwith, and after a short spell with BT21s, the Brabhams were swapped for a pair of Geminis. The Gemini-DAF combination proved to be the best match-up between chassis and CVT, as a late-season charge saw Beckwith take second at Brno in early September before winning outright at Brands at the end of October, followed up by a third at Jarama, in the wake of Clay Regazzoni's emerging Tecno. Guest-starring in the non-championship Swedish Stockholmsloppet at Skarpnäck on September 24, Beckwith took pole while Van Lennep went on to win the 20-lap race.

Having seen the quick Tecno beat Beckwith at Jarama, DAF decided to up the ante one more time, moving closer to home by handing over operations to Racing Team Holland, the famous Dutch outfit run by Pon and Slotemaker, and replacing the successful Gemini with a couple of Tecnos. The change to Tecno chassis for 1968 seemed wise, as was proven by the numerous wins taken for Tecno by Wisell, Peterson, Jaussaud, Regazzoni and Cevert. In all, that season Tecno cars won 32 out of 65 international F3 races. However, none of them sported a Variomatic transmission. To top that, the team shot itself in the foot when it did lead a race. Tellingly, the final race of the season – what turned out to be DAF’s last F3 break – ended with Van Lennep and Beckwith shunting each other out of first and second position…

Rallying

DAF’s fortunes in rallying were slightly better, and maybe the DAF image was better suited to it too. Having racked up class wins in the major international rallies, DAF soon transferred its effort to gruelling rally marathons, which put an emphasis on endurance and reliability rather than outright speed.

However, it hadn't been DAF's intention at all to enter motorsports, but after privateers Rudi Hunger and Maurice Colinet had shown in 1960 what a 600 was capable of, entering rallies in their native Austria and Belgium, it slowly began to dawn on DAF that rallying could prove to be a breeding ground for innovation. Indeed, on the Austrian snow the Variomatic appeared to work as a clever form of traction control, and the lightweight chassis also helped on slippery surfaces. Apart from the numerous under-700cc class wins, a shock overall Dutch national win in the 1961 Tulip Rally by Van den Bergh/Smulders (in car no. 211) put even more thought into DAF's minds.

By 1964, DAF Racing Team not only focused on the F3 project but was also entering rallies with Rob Slotemaker and Claude Laurent. At first, the team ran bog-standard 750s in events such as the Neige et Glace, the Coupe des Alpes and the Corsica rally. For 1966 the team shoehorned the 44's 850cc engine into the Daffodil, leading to yet more under-850cc class wins in the Tour de Corse (11th overall), the Marathon de la Route and the Limousin and Bayonne rallies. The next two years saw the 44 take over before the 55 was introduced as the marque's car of choice. In its short spell in service the 44 racked up class wins, from Monte to San Remo, driven by the likes of Claude Laurent, Jacques Marche, Jacky Coolen and Jean-Louis Haxhe, and even delivered a national title to Austrian Karl Raab. Gijs van Lennep also had his spell in rallying, along with brother David, as they headed the DAF entry - now using 55s - for the 1968 Monte Carlo rally. But after a class win by Laurent/Marche in the 1967 edition, the Van Lennep brothers faired less well, colliding with a bridge…

Gradually, the DAF Racing Team transferred its efforts to monster rallies, as the Variomatic machines were hard to beat on reliability. The 1968 London-Sydney marathon proved to be a memorable event – with the simple DAF 55s of Slotemaker and David van Lennep making it all the way down under. The “Marathon” road-car kit became a very popular after-market item soon after, before DAF introduced a proper out-of-the-box Marathon Coupé, the examples of which are still among the most sought-after classic DAFs. Still, it couldn't match the rivaling Mini Cooper by a long stretch. On loose surfaces, however, the 55M in the capable hands of Claude Laurent pressed on to some remarkable results, such as a 3rd overall in the 1969 Acropolis.

The 55M remained in service until 1973, when it was replaced by the Marathon version of the 66, which later got a 1.3-litre engine. By that time DAF had tried its hand at road racing, entering 55Ms for the Nürburgring 24 hours – still an event that rewards reliability over speed – and coming back with a 2nd overall for Geller. Most rally entries were now confined to Dutch and Belgian events such as Ypres, Tulip, Boucles de Spa and ELE, but Laurent kept persevering in the Monte Carlo. In 1974 DAF equipped him with the “666” prototype that Haxhe used on his way to an overall win in the 1973 Boucle de Spa. Laurent managed 30th overall. In 1975 several privateers continued with the 66 but as soon as Volvo had taken control of the Dutch company, its rally activities were scrapped.

Touring cars

At the start of the seventies DAF introduced the “555”, a sports coupé that proudly carried the accumulated performance technology of the 55M and the F3 project. The three 555s were built to conform to FIA Group 6 sportscar regulations, so they could run as prototypes without meeting homologation requirements. The cars started out in local rally events before they made their first circuit appearance in the 1970 Coupe de Benelux at Zandvoort, Haxhe driving.

By this time a standard-spec 55M had already taken part in the 1969 Dutch Touring Car Championship. This had gathered interest in the DAFs’ capabilities as a touring car, and for 1970 Hans Deen, the later Zandvoort circuit director, entered a Group 2 55M. The tuned 90hp machine was bang on the pace, fuelling orders from competing teams such as Gulf-Star. By 1972, the DAF was the car to have in Group 2 and Gulf-Star driver Han Tjan led the onslaught on the national title, with DAF cars taking five of the first six places in the 1000-1150cc championship. The 66 Group 2 follow-up proved to be less successful, though, and with Volvo coming in, touring-car activitities were halted with immediate effect.

Rallycross

The 1970 season saw Holland’s first national rallycross championship. One of its main entrants was Jan de Rooy, who was to become a DAF mainstay and, amongst many other successes, the later Dakar winner in one of DAF’s monster 4x4 trucks. In his debut year as a car racer the former motocross ace fielded a Gordini-engined DAF 55, as he took on a whole range of rallycross cars including Minis, NSUs, DKWs, Ford Anglias and VW Beetles – to great effect, as he took both national and international titles.

As the sport’s popularity quickly gathered pace in Britain, Holland and Scandinavia, helped by its television-friendly format, De Rooy switched to the 555 for 1971. For this, his ZAV Hofnar team had two of the 555s converted to rallycross spec. The first one was powered by the original water-cooled 4-cylinder 1.4-litre Gordini engine, but soon it was succeeded by ‘t Bultje (“The Bump”, referring to the bump in the roof), which was powered by a 185hp 1.8-litre Cosworth BDA. Remarkably, the car used the F3 Variomatic, placed under the driver’s seat! And it was four-wheel drive too, as the engine sat where the passenger seat used to be, with the Variomatic connecting to both the front and rear axles.

DAF took an immediate interest and Jan de Rooy and brother Harry were recruited into the works Camel DAF Racing Team, with the 4WD 555s going from strength to strength in 1972. It all came to an end, however, when the FIA banned four-wheel drive. This led to Ad van Brussel’s Team Nieuwe Revu taking Jan de Rooy’s Ford engine and putting it in a rear-wheel drive 66 Coupé for 1973. DAF decided to go ice racing with their 4WD cars, with Claude Laurent taking 4th overall on the famous Andros track of Serre-Chevalier. Meanwhile, for 1974 De Rooy briefly returned with a tube-framed DAF 66 silhouette, before DAF faded away against a new breed of rallycross machines.

However, the marque’s rallycross antics had a remarkable spin-off in the form of an infamous driving-backwards circus at Zandvoort, which became some sort of national sport in Holland during the 70s. With their Variomatic transmissions the DAFs were the cars of choice for this popular show on national television – in reverse they could race just as hard as they could in the proper direction! Still, it made the obsolete DAFs even more of a laughing stock.

The aftermath

Thereafter, the CVT never returned to racing, although two attempts ran aground at the last gasp. In 1979 VDT started a cooperation with Ferrari to introduce an F1 CVT, but in 1980 the project was canned as soon as the funds were redirected towards turbo development.

The racing Variomatic’s swansong was sung in 1993 – but what a beautiful coda it was. Co-developed with the Williams F1 team, the championship-winning Renault-powered FW15C was mated to a VDT transmission. Test driver David Coulthard set some spectacular times at Silverstone, as he gave on-lookers the eerie sensation of a car going through Copse and Becketts with its V10 screaming through its open exhausts at top power. Initially, the car found a home at the DAF museum in Eindhoven, where the above picture was taken, before it moved to VDT's head office in Tilburg. Here you can also see the transmission without its natural surroundings.

As a sensory experience it was far removed from anything we had ever heard before. Perhaps that is why CVT will never make a breakthrough – it needs just too much getting used to.

Book and Web references

The pictures with this article were mirrored from the above sites.
The Jack Brabham picture is courtesy of the GP Library. The Williams CVT pictures were taken by Kevin Smeekens and are kindly reproduced here.