Tech Briefs
Ricardo's durable motorsports transmission
 Cutaway illustration of Ricardo's transmission shows all internal features, with the semi-automatic selector system on the top. |
The Audi R8 racing car employs a Ricardo transmission capable of 8000 rpm and 600 N•m (440 lb•ft) input torque. The "problem-free" transmission worked through more than 50,000 gearshifts without a single malfunction in 2000. The scenario has repeated itself in 2001, a feat that bodes well in the American Le Mans Series (ALMS) of endurance racing. "Reliability is the single most important target because you've got to finish every race and finish every race in the fastest time possible," said Mark Barge, Director of Motorsport for Ricardo Motorsport in Leamington Spa, UK.
Ricardo designed and developed the six-speed sequential transmission—which forms an integral part of the R8 structure—by applying all aerodynamic and suspension loads to the rear of the car. To meet Audi's objective of reducing its 1999 transmission's mass by 20 kg (44 lb), Ricardo engineers achieved a 20% smaller package with the aid of structure optimization software tools and a high-strength magnesium alloy (MSR-B). "This allowed the optimum distribution of material with the smallest wall thickness to be achieved," said Barge.
For the 2000 season, Ricardo improved the torsional stiffness of the transmission casing design using topology optimization and FEA modeling, and replaced a mechanical gearshift configuration with a semi-automatic gearshift system similar to those used in Formula 1 racing cars. "There are no manual shifts," said Barge. "It isn't a driver-assisted shift in any way." Ricardo's pneumatic shift system, which uses a processor and specific software algorithms, essentially evaluates an upshift or downshift as indicated by the driver triggering a steering wheel switch. "The shift system is not there to take the driver's place, but to eliminate errors," said Barge. "The shift system makes sure that every one of the driver's shift commands can be executed safely and efficiently."
 Computer models of the transmission's gear sets, final drive, and differential arrangement. |
Compared to conventional manual gearshifts, which take about 100 ms, the pneumatic gearshifts take about 25 ms. But the 65-kg (143-lb) fully dressed transmission seen in the 2001 race season is targeted for quicker gearshifts.
"We genuinely believe we've reached the limit on structural optimization, but we will be focusing on even faster gearshift times," said Barge. "We're working on how to continue to reduce shift speed time and how to dissipate the load that's generated from the engine during a gear change." Consider that in the 2000 season, there were 54 gearshifts each lap of the 368 laps—translating to 19,872 gearshifts—at the 24 Hours of Le Mans. By reducing gearshift time by 5 ms (going from 25 ms to 20 ms), the result would equal faster lap times. "You'd see the difference on the track," said Barge. "If it took approximately 4 min for one lap, going from 25 to 20 ms would represent 40% of a lap by the end of a race. Gearshift time savings could also impact tire and refueling strategy."
- Kami Buchholz
ALMS tidbits
Sanctioning body: In 2002, all American Le Mans Series (ALMS) races will be officiated and sanctioned by the International Motor Sports Association, formerly known as Professional Sports Car Racing.
Series background: ALMS features sports car endurance races based on the famed 24 Hours of Le Mans. The 2002 season marks the fourth year for ALMS.
Classes: Le Mans Prototype 900 (LMP 900), which includes the Audi R8; Le Mans Prototype 675 (LMP 675); Grand Touring Sport (GTS); and Grand Touring (GT).
ALMS prototype chassis manufacturers: Audi, BMW, Panoz, Lola, Reynard, Cadillac, Ferrari, Riley & Scott, Debora, and Courage.
ALMS prototype engine manufacturers: Audi, BMW, Elan Power Products, Judd, Rafanelli, Cadillac, Ford, Porsche, Nissan, Volkswagen, Ferrari, and Peugeot.
Schedule: The 10-race schedule in 2002 opens with the 50th running of the Mobil 12 Hours at Sebring (Florida) and ends with Audi Presents Petit Le Mans at Road Atlanta in Braselton, GA. Petit Le Mans runs whichever comes first—1600 km (1000 mi) or 10 hours. The 2002 schedule includes a special invitational race in Kuala Lumpur, Malaysia.
Audi recap: In 2000 and 2001, Audi won the three long-distance classics: Sebring, Petit Le Mans, and Road Atlanta. Manufacturer and Team championships were won by Audi in 2001.
