XTRAC INDY GEARBOX
Indy gear
Better, cheaper, longer lasting and approved by everyone. That was the brief, this is the result
BY LAWRENCE BUTCHER
the outgoing IR07 chassis, with the intention of reducing costs to teams, increasing safety and provide exciting racing for the fans. Incorporated in the DW12 package is a new, six-speed, sequential transmission that will be produced by UK-based manufacturer, Xtrac. The company was the logical choice as it previously supplied a transmission to the series, in the form of the Xtrac 295, which provided reliable service for the best part of a decade. The new gearbox is the
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product of a coordinated effort between everybody involved, which made for an unusual development programme, as Richard Billyeald, principal engineer at Xtrac, explains: ‘It was a very interesting project because it was not just us and Dallara. It involved the teams and IndyCar as well. So the teams obviously have their own wish list and some things we could do and others we couldn’t. You ask 12 teams what they want and you will usually get 12 different answers back. IndyCar were obviously setting the spec with Dallara too, so there was a good relationship with them, too. However, the budget
012 sees the debut of the Dallara DW12, the all-new IndyCar racer, designed to replace
for the transmission was considerably tighter, thanks to IndyCar’s cost-saving intentions, so incorporating all of the improvements [we wanted] was challenging.’ The new transmission,
designated the 1011, has minimal carry-over parts from the old unit, though it is not an entirely new design. ‘We had a number things we wanted to change from the original 295 ’box, and some features we wanted to retain,’ highlights Billyeald. ‘It was a well regarded ’box and the guys working on it liked it and liked working on it. We wanted to maintain serviceability, with the gear cluster coming out of the back [so] you can change it mid-race, which has been done! But there were some improvements, such as changing the overall ratio without breaking the ’box off the car, that we also wanted to incorporate.’
CLOSE COMMUNICATION The working relationship with chassis manufacturer, Dallara, was a close one by necessity, with modern communications making occasions such as daily conferences a simple matter. This close working partnership was vital as the transmission forms an integral part of the chassis, to an even greater
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www.racecar-engineering.com • May 2012
extent than it did on the outgoing chassis. This is thanks to factors such as the location of suspension components. On the previous Dallara IR07 chassis, the suspension rockers were mounted on the bellhousing, whereas on the DW12 they are integral to the gearbox casing. The result is a gearbox that has grown in length and a bellhousing that has shrunk. Considerable collaboration was also required in relation to the design of the rear crash structure and the attendant tests. ‘The side push off and rear crash tests were very important. The rear crash structure was
initially tested on its own and then attached to the gearbox and re-tested as a whole,’ explains Billyeald. Xtrac’s F1 knowledge and experience gained with series such as A1GP meant that accommodating the impact requirements was a relatively straightforward task. The close sharing of CAD and
simulation data with Dallara, combined with the company’s own extensive FEA abilities, also
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