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The clash between the diesel Peugeot (Ricardo) in the foreground and Audi (Xtrac) at this year's Le Mans 24 Hours highlighted the need for transmissions to withstand increasing amounts of torque.

EuroAuto: Gearboxes and the Challenges of Racing

Although they were once not thought about much, the abilities, functions, and packaging of transmissions are key in racing today.

Although the gearbox in a race car and a road car serves the same function—acting as the link between the engine and the driving wheels—otherwise there is very little in common between gearboxes in each. Where automotive engineers seek refinement and ultimate smoothness, their motorsport counterparts want as quick a shift as possible. Noise and refinement are simply not part of their considerations. For many years, the gearbox has been given less attention than other aspects of race cars. Lately, however, it has moved far more center stage and is now very much on the radar of a team’s technical director or chief engineer. According to Iain Wight, director of motorsport development at engineering consultancy Ricardo (http://www.ricardo.com/engineeringservices/motorsport.aspx), this change has occurred for a number of reasons, one being the change of characteristics of the modern race engine, and another being the recent awareness of just how important the transmission can be in a racing car. “What we are currently seeing is an increase in torque levels,” he says, adding, “The customers are changing quite dramatically in that teams and manufacturers are far more aware of what they want from transmissions now compared to 10 years ago, when even for the top teams it was more or less a commodity that could be bought off the shelf.”

This has now changed quite dramatically, says Wight, with the bespoke gearbox de rigueur across the board. “The way that we’ve been working recently has meant that customers come to us very much with ideas on how they want the transmission to be packaged and arranged within the vehicle, and we help them accomplish that by working with them. We obviously provide a suitable design for the transmission, but there is far more emphasis from the manufacturer on how the layout is going to suit the packaging with regard to the engine, the aerodynamics, ensuring that the underbody temperatures are kept in check, and that the suspension layout is correct. We regularly have torsional stiffness targets from companies that we have to achieve.” Development proceeds in partnership with the customers, and is one part computer-based analysis and one part experience.

In circuit cars, aerodynamics and engines will always take priority over the transmission, says Wight. Suspension layout is generally secondary to the aero and the engines but is still a primary concern of the vehicle packaging. The transmission generally fits in the space that is left. “From our point of view it makes it very interesting because we have to design different solutions for different applications all the time. This year alone we have designed four new transmissions and we’ve modified an additional two transmission housings to suit what the manufacturers wished to do going into 2008. Two years ago, we were maybe doing one transmission a year, so the higher demands on us are mainly driven by the customer as they are becoming more demanding and know more of what they want.”

A case in point was the work Ricardo did for Audi Sport in the development of the sports racing R8. The German team was adamant that it wanted a quick-change rear end in the event of any problems during the race, especially the 24 Hours of Le Mans, but Ricardo had the self-belief that it could make a gearbox that would last the distance. “There is obviously an established base for supply within motorsport, and we were quite new to the game with the Audi R8 in 2000,” says Wight. “Audi Sport realized that the transmission could be a weak area so the car was designed so that the rear end could be changed in about four minutes. We designed the transmission to last 24 hours, without compromise—we didn’t design it to have a quick-change cluster. They used the quick changeability of the rear end to assist them in serviceability of the vehicle itself. We’ve carried that philosophy over the last seven or eight years to all the transmissions and while easy access for mechanics is always a priority, we will endeavor not to compromise the design by building in ease of access and therefore compromising the overall efficiency of the design.”

There are a number of considerations in the design, from light weight to performance longevity. Wight says, “With any mechanical device, whether it’s an engine, suspension piece or gearbox, the more parts you have, the higher the risk of unreliability with greater possibility of parts failing. If you look at any Ricardo transmission, they are very simple and very elegant in design with a minimal number of parts. It’s enabled us to produce lightweight transmission systems that operate very simply but fulfill all the requirements of packaging, weight and longevity. This is one of the reasons why six of the current sports racing car manufacturers use our transverse gearbox for long distance races and why the diesel powered Peugeot 908 HDI FAP has a bespoke Ricardo unit.”

When it came to the diesel-powered Audi R10, though, it was Xtrac Inc. (www.xtrac.com) that won the contract. As a specialist transmissions manufacturer for the last 27 years, it has carved out for itself a dominant position in the motorsport market, producing the Xtrac “100” transmission, its first Formula One customer gearbox, in 1990. It now has an involvement in one form or another with all 11 teams on the Formula One grid. However, there is more to this company than providing transmissions to the top end. At the end of last year it introduced the 516, a high-performance front-wheel drive gearbox that had been designed specifically for cars competing in the World and British Touring Car Championships. It was immediately successful and was the transmission of choice on the British championship’s winning Vauxhall Vectra.

Winner of the Most Innovative New Motorsport Product of 2007 award at the end of November, this new transmission competed in all 30 rounds of the British Touring Car Championship races this year with no mechanical failures and achieved consistent success on the podium with cars equipped with the gearbox winning 15 races with 14 second places and 14 third places for a total of 43 podium finishes.

Another specialist transmissions company is Hewland Engineering (http://www.hewland-engineering.co.uk) that, like Ricardo and Xtrac, is based in the U.K., but unlike the other two it does not have any U.S. operations. However, the company has built up a good business in the country and is the sole supplier to ChampCar of its purpose-made gearbox and semi-auto system. Next year will see further strengthening of its partnership with Elan Motorsport Technologies of Atlanta, Georgia (www.elanmotorsports.com), which is supplying the chassis for the forthcoming 2009 Superleague Championship, with the introduction of a new semi-auto, paddle-shift transmission. “Our outlook for 2008 is still to provide tailor-made solutions or off-the-shelf ones,” says William Hewland, the company’s CEO. “The market leans toward one-make racing where ‘spec’ transmissions are required together with semi-automatic paddle shift control. These series need a certain skill set to be managed well, of which Hewland has unparalleled experience.”

Looking to the future, though, it seems to be one filled with diesel racing cars, not only following Audi’s success at Le Mans and in the American Le Mans Series but also SEAT Sport’s successful entrée into the World Touring Car Championship midway through this season which saw it take the fight to all-conquering BMW. Ricardo, Hewland and Xtrac amongst others are gearing up for this growing new market in Europe. “We already have wider cluster versions of the previous touring car gearboxes suitable for diesel applications,” says Hawkins, “and we see the advent of more diesel cars as an opportunity for us as we do have product that is suitable.”  

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