There's no shame in not knowing what a limited slip differential is. After all, every budding car guy has a first time trying to parse Brian Beckman's The Physics of Racing. (And many of us still don't understand the entirety of it after multiple perusals.)

So if you're trying to wrap your mind around just what this Torsen thing is, there's no excuse for not watching this new video from Scion. While it's basic, it does explain the rudimentary physics behind a limited slip in just two minutes. If nothing else, it should get you started in looking for some more comprehensive information.

Scroll down to watch the video.


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    • 1 Second Ago
  • 23 Comments
      Gorgenapper
      • 2 Years Ago
      Interesting, but I would have liked to see the inner workings of the Torsen (TORque SENsing) diff when it takes corners.
      Jason Parry
      • 2 Years Ago
      This is actually incorrect and misleading, I'm surprised this got out there especially with the cheesy music and 50s narration. all cars have a DIFFERENTIAL like they are talking about (wheels spin at DIFFERENT speeds such as going around a corner) what makes it LIMITED SLIP is difference (SLIP) between the two is LIMITED. That way the wheel that is SLIPPING (vs the road) still gets power which lets you slide. A normal differential would give no power to a slipping wheel and you cant drift. this video is about a differential and has no bearing on the performance benefits of an LSD for the FRS. Oh and its cheesy.
        iraceastationwagon
        • 2 Years Ago
        @Jason Parry
        I disagree. The video is pretty much correct. The limited slip feature is very briefly mentioned; although I agree the explanation of it could be better. It seems most of the video's emphasis was placed on explaining the torque biasing feature of the Torsen differential. This is understandable since that's what sets this type of differential apart from the other types of LSD's. Also, a minor correction to your comment - A normal open differential sends almost ALL the power to the wheel that's spinning. Even so, it's not impossible to drift/slide with an open diff, its just more difficult to hold it.
          EXP Jawa
          • 2 Years Ago
          @iraceastationwagon
          Not a bad video, simple concise. No animation (or mention) of the helical gearing though. Here's what an open diff does: it split available torque 50/50 ALL the time. Note the use of "available torque". That has nothing to do with flywheel torque and everything to do with tire traction. When conditions are ideal, the open diff will allow an equal amount of torque to both tires, up to the limit of what tire traction allows. Thus, "available" torque. It's when an imbalance of traction occurs between the left and right side that things get murky. The differential will be limited by which ever tire has less traction. Essentially, it will only allow the high traction tire to have an equal amount of torque to the low traction. Consequentally, the 50/50% split is maintained. Any extra "power" that might be applied is lost in wheelspin, further torque cannot be supported, so it's never developed. That's why people say an open diff sends all power to the tire with less traction. That's a crude summary of what happens, but it doesn't really describe what's actually going on. This is where LSD's come into play. Specifically, an LSD is designed to allow and support an imbalance of traction from left to right without spin occuring. The ratio that this occurs is often, but not always, refered to as the torque bias ratio (TBR). The video makes a brief tangential reference to this toward the end. This imbalance is created by generating internal friction - friction within the diff resists wheel spin, thus allowing the imbalance to be supported. Clutch plate diffs do this with - surprise - clutches. A helical gear diff does it by generating internal thrust forces on the gearing that pushes them under load against the case interior. The net result in both is that friction is created to generate slip resistance. But the two different methods lead to significantly different characterists with regards to how the traction imbalance support, or biasing ability, comes into play and interacts with the chassis. That, however, is a whole different discussion that I'm not getting into. This post is already too long. Anyway, if it sounds like I've rehearsed this speach before, I have. I work for JTEKT Corp, the company that makes Torsen (trademark) diffs, though I didn't have anything to do with this application...
        wilkegm
        • 2 Years Ago
        @Jason Parry
        Mostly correct, but.... A normal (open) diffential sends power to both wheels, all the time. The difference is the response: the wheel with no traction takes this power to spin uselessly, while he other wheel provides a tiny amout of drive. I was really hoping to see a nice animation of a Torsen diff, but alas...
      Alex Arndt
      • 2 Years Ago
      i can feel the diffrence in my Boss 302. Good job on Toyobaru for including a mechanical LSD. I wouldn't want a sports car without one.
      mnoswad1
      • 2 Years Ago
      worst description of a limited slip axle I've ever heard. I know how they work, whether torsen or clutch, but I have no idea what that video was talking about Seemed like they tried to dumb down the description for the "average" consumer,but actually made it worse. Any youtube animation of a ltd slip diff will explain it better than this video does.
        EXP Jawa
        • 2 Years Ago
        @mnoswad1
        They weren't explaining how the diff actually functioned, but rather how it impacted the driver. An it was reasonably accurate in what characteristics it imparted on the car. Frankly, that's all the average buyer will care about.
      eyalny
      • 2 Years Ago
      how do they know what subaru did in this car? this is a subaru sold by toyota, toyota or scion in the case got nothing to do with this car
        Drakkon
        • 2 Years Ago
        @eyalny
        Measurably untrue, but never let facts stand in the way of a good story!
        Wyrmdog
        • 2 Years Ago
        @eyalny
        I'm fairly sure English isn't your first language, so you get a pass on the awful sentence structure. But like Drakkon says, you're flat wrong.
      Greg
      • 2 Years Ago
      That video doesn't explain how it works.
      Hazdaz
      • 2 Years Ago
      I think these type of videos are great. More of them should be made (from any automaker) to help explain some of the rather technical aspects of modern cars to people that just might not understand what is happening. Its easier to link to a video, than trying to explain what Direct Injection is exactly, or how a turbocharger works to someone that is not familiar with these technologies.
      Drakkon
      • 2 Years Ago
      this article needs a sticky! the point is to tell potential buyers of this car WHY Torsen and limited slip improve the driving experience. NOT to tell you how it's made and such. Relax! If you know the differences between diffs (diffs between diffs) then this little piece of markets is not for you.
      Schadenfreude
      • 2 Years Ago
      Why no Subaru BR-Z articles? Why is it always the Scion FR-S?
        Drakkon
        • 2 Years Ago
        @Schadenfreude
        Because the Scion marketing department is paying to put the article out there. They create the content, and Autoblog posts it. If the Subaru marketing department is not willing to spend the money, they message won't get out.
        Jeremy Pennini
        • 2 Years Ago
        @Schadenfreude
        Toyota/Scion has done more marketing. Maybe because they have more cars to sell. Autoblog reports when automakers do something. Toyota/Scion made a video series on their new car.
        wilkegm
        • 2 Years Ago
        @Schadenfreude
        When Subaru disperses cute press-kits you'll hear about it. Toyota and Subaru have an agreement that coordinates their marketing of the respective cars, right now is just Toyota's turn.
      Stephen
      • 2 Years Ago
      It would've been cooler if they showed the car breaking into a drift in the middle of the info graphic. haha. Good on them for attempting to educate their customers though.
      pblcsrvce
      • 2 Years Ago
      this is nothing new. audi and other manufacturers have been doing this for a minute.
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