A popular engineer explains in simple terms and with great examples why Toyota has made a lot of progress with its all-wheel-drive (AWD) system called GR-Four. It’s the first new such system made from the ground up by the Japanese automaker after a 20-year hiatus. As you may have guessed already, it was important for the company to get it right. Here’s how they’ve done it.
Jason Fenske runs the popular YouTube channel Engineering Explained. He talks about different types of cars and tries to go beyond the usual stuff we see presented on traditional media outlets. For those who want to understand cars better, it’s a good source of information that’s both easy to follow and comprehensive at the same time.
Fenske now decided to talk about Toyota’s AWD system, and he provides us with great insights about what has been achieved. The GR-Four is installed on the GR Corolla and GR Yaris. This decision was meant to spearhead the launch of the Gazoo Racing (GR) brand – Toyota’s high-performance division.
After having a lengthy talk with Naoyumi Sakamoto, who is the Chief Engineer for the GR Corolla, Fenske took it to YouTube to show his whiteboard drawing skills and tell followers and others why the GR-Four AWD system is, as he calls it, “brilliant.”
But before exploring the YouTuber’s claims, you should know that Toyota’s GR AWD system uses a rather simple recipe – it has an open or Torsen differential at the front (customers can choose what they want), an electronically-controlled, electromagnetic multi-plate clutch pack installed in front of the rear axle where there’s another open or Torsen differential.
The three driving modes (Normal, Sport, or Track) can split torque 60/40, 30/70, and 50/50. The thing that surprises many is that this system allows for speed differentiation between the axles while the torque is split evenly or, better yet, 30/70 without a center differential.
The short answer that clears all the confusion is the JTEKT-supplied clutch pack known as the Intelligent Torque Controlled Coupling (ITCC). It makes use of a diamond-like coating (DLC) applied on 12 pairs of clutch plates that give it durability. This unit makes sure that the rear differential is always geared approximately 1% faster than the front differential. Slightly different gear ratios allow for much more drive force to be directed to the rear wheels, even when there’s no slip detected at the front wheels.
But Fenske takes it from the very beginning and explains everything you need to know with good visuals. Watch the video and find out why Toyota's GR-Four AWD system is simple and smart, and it even has the potential to be reliable long-term.
Car shows on TV and his father's Fiat Tempra may have been Florin's early influences, but nowadays he favors different things, like the power of an F-150 Raptor. He'll never be able to ignore the shape of a Ferrari though, especially a yellow one. Full profile
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