• Apr 16, 2008
Birthing a car is always difficult, and Tesla has seen its share of problems. The biggest hurdle to getting its all-EV Roadsters in customers' garages has been the transmission. Initially the company wanted to have a two-speed unit, but the unit from its first supplier, X-Trac, wasn't durable enough. Tesla then contracted Magna to help build a tranny, before a final try at designing its own transmission also ended abortively. In the end, to get cars rolling out the door, changes were made to the motor so that a single-speed transmission could be fitted.

Magna doesn't seem upset that it was just a stepping stone – that's business. What the company would like, however, is to get paid for the work it performed. Magna is also telling Tesla "told you so" by claiming to have suggested a single-speed unit back in 2006. To recover its $5.6 million, Magna has filed suit in San Mateo to force the issue, which coincidentally comes not long after Tesla filed suit against Fisker, which it initially hired to designs its next product, the WhiteStar sedan. What goes around comes around, we guess. The legal wranglings haven't yet made a dent in Tesla's operations, but Magna's lawsuit could bolster the case of frustrated buyers who have yet to receive their cars, should those customers decide to also take to the courts.

Update: Tesla VP Darryl Siry contacted us to clarify the issue with the original X-Trac gearbox. Apparently the problem was not one of actual durability of the transmission itself. Tesla evidently spec'ed out a two speed unit with no clutches. The design intent was to do clutch-less shifting and manage the torque output of the motor during the shifts. Unfortunately the rotational inertia of the motor made this plan unworkable as the torque output couldn't be changed fast enough. According to Siry there were never actually any mechanical failures of the X-Trac transmission, it was simply a matter of Tesla not being able to get their control strategy to work adequately with the hardware. Subsequently Tesla contracted Magna to develop a dual clutch two speed gearbox. Unfortunately, this is the design that had durability issues leading to Tesla's ultimate decision to revise the motor for more power and go with a single speed unit for production. The vehicles running with the interim single speed gearbox are actually using the original X-Trac box with the lower gear locked out (for prototypes) or removed entirely (early production cars). - Sam


[Source: Autoblog Green]


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  • 12 Comments
      • 6 Years Ago
      oh, that suing culture....
      • 6 Years Ago
      Be a shame to see this beautiful car die because of legal squabblings.
      • 6 Years Ago
      pretty crazy that x-trac couldnt get a tranny to work. being such a big racing company.

      i understand that the electric motor is at full torque when they change gears. but you would figure that with x-trac's racing background they could of come up with something.

      unless its just not possible to build a multispeed tranny with such a powerful electric motor in a performance car.


        • 6 Years Ago
        x-trac, Magna, Ricardo (who made transmission for veyron, ford gt) were tried by Tesla. I mean these aren't second rate transmission builders, they all have lots of experience and reputation, but somehow it didn't work out.
        I'm hoping maybe in the future, when Tesla actually gets going on the sales, recovering the initial development costs and start making profit, then maybe they should have another go at the 2 speed. The only thing holding them back from a higher top speed is the single speed transmission. It's probably harder to make one given the instant torque and high peak rpm for Tesla's motor, but I don't think it's an engineering impossibility to build a 2 or more speed transmission for a high performance EV.
      • 6 Years Ago
      Give it up Tesla...
        • 6 Years Ago
        You work for Generally Malevolent huh? Go stick yer head in a toilet. I hear thats how you guys come up with designs and "innovative breakthroughs" anyway.
      • 6 Years Ago
      Interesting that the Fisker car is named "Karma" that Tesla alleges is using "stolen" intellectual property. Not saying Fisker didn't do what he's accused of, but it's funny how what went around is apparently coming back around. I wonder if Tesla sued Fisker to repay Magna in the first place.
        • 6 Years Ago
        He's busy solving some case studies on the American car industry.
      • 6 Years Ago
      Nice car.
      • 6 Years Ago
      One error in the article (and others): The Xtrac transmission never had reliability issues. It has proven rock solid over the years and for that reason we are using an Xtrac box for our interim transmission. The reason we moved away from that design was that we had originally tried to design the gearbox to have clutchless shifting and to accomplish the shifts entirely through motor control but this proved difficult on our end due in part to the time it takes to spin down a heavy rotor that is rotating very quickly.

      The reliability issues were with the Magna unit only. We’ve established the fact that the units delivered were not working well so that led to a disagreement between the parties as to what was owed on the contract. These types of disagreements sometimes end up in court.
        • 6 Years Ago
        While you're here, would it be possible to show us a picture of the White Star sedan that's causing all the contoversy, Please?