Tesla Finalizes Single-Speed Transmission, Ups Output, Range

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The thorn in Tesla's side, the troubled single-speed transmission for its all-electric Tesla Roadster, has finally been approved for production, and with it comes an announcement of more power and better range. After durability problems with the original single-speed transmission, Telsa was forced to used a two-speed cog swapper for production. But now, after re-sourcing the business to transmission mega-star Borg Warner, the redesigned single-speed is ready to go and offers big benefits. Because of the additional capability in the transmission, the peak torque has been raised from 211 lb-ft to 280 lb-ft; a heady number considering peak torque arrives at zero rpm with an electric motor. Despite the higher output, the EPA estimates show a 10% increase in range. That's a pretty neat trick. Complete details below.

Tesla Motors Selects BorgWarner for Production of New Gearbox for Tesla Roadster Deliveries of 27 Roadsters Completed to Date, Production and Delivery of Roadsters To Accelerate With Final Powertrain Solution San Carlos, CA – Tesla Motors Inc. has selected BorgWarner Inc. for the production of a single-speed gearbox for the Tesla Roadster and is initiating a ramped-up production rate. So far, 27 customers have taken delivery of Roadsters. Tesla engineers developed the specifications for the new gearbox and provided them to BorgWarner. The new gearbox is an integral part of an enhanced powertrain with significant performance and efficiency improvements. The new powertrain delivers about 30% higher motor torque on a single gear ratio, and it achieves a 10% higher EPA combined range. “Last December, when the two-speed transmission designed by a previous supplier proved not to be durable, we announced we would modify our approach,” said JB Straubel, Chief Technology Officer of Tesla Motors. “By using a more powerful inverter and an enhanced motor design, we were able to implement a single-speed gearbox and still achieve our original performance goals. In fact, the new setup is superior in almost every way.” The new gearbox is designed for the higher peak torque levels of the new Roadster powertrain, which has increased from 286 Newton-meters (211 foot-pounds) to 380 Newton-meters (280 foot-pounds). The new powertrain achieves an EPA combined range of 244 miles on a single charge, up from Tesla’s previously announced EPA range of 221 miles. Production of Tesla Roadsters began in March, and the first vehicles were built with an interim transmission design. Customers who own Roadsters with the interim transmission can have their powertrain upgraded free of charge. Tesla Motors starts production of 10 new Roadsters each week. Customers typically take delivery four to six weeks after production begins. The company expects production to ramp up to at least 20 vehicles per week within a few months and 40 per week by early 2009. “Successfully implementing the new gearbox in less than a year was an incredible technical challenge and huge accomplishment for Tesla’s engineers,” said Ze’ev Drori, Chief Executive Officer of Tesla Motors. “Now that we have a final powertrain design, in a matter of months there will be hundreds of Tesla Roadsters across the country. We’re heralding nothing less than a new era of the automobile.”