I don’t know if you’ve seen the internet lately, but the 2023 Toyota GR Corolla is causing quite an uproar. With all-wheel drive, a manual transmission and a 300 horsepower three-cylinder engine, how could it not? But those headline figures only tell part of the story.
There’s a lot of cool technology at work behind the scenes that makes this hot hatch so rad, and luckily for us, Engineering Explained’s Jason Fenske is around to help break down some of that tech. This time, he’s giving us the lowdown on how the GR Corolla’s brand new (and very cool) all-wheel drive system works. Spoiler alert: It’s kind of complicated.
So, the tl;dr is this: the GR Corolla uses an active clutch pack on the input shaft of its rear axle to manage the torque bias between the front and rear wheels. This clutch pack acts as a brake on the front axles, and the more braking force the clutch pack applies, the more torque the rear axle sees. Following so far?
So, this braking force method works because the rear axle is geared just an eensy bit lower (0.7 percent, to be exact) than the front axle. This means that the rear axle is always trying to turn faster than the front, which means that in order for the wheels to all turn at the same speed (in a straight line), that clutch pack on the rear axle has to slip a little. That slip gives the vehicle’s computers something to work with when calculating adjustments to the torque split.
The GR Corolla has three basic torque splits from which a driver can select. The front-biased mode sends 60 percent of torque to the front wheels, with 40 percent going to the back. Track mode makes that 50/50, while rear-biased mode sends 70 percent of the available torque to the rear axle, allowing you to do silly stuff. These targets change based on grip levels and road conditions, but you get the idea.
Seriously though, Jason’s explanation is much better than mine, and it would behoove you to watch it. Also, he has a very cute cat named Bucket, and Bucket’s gotta eat, so give Jason the views.