What makes Subaru's AWD system 'better' than a Honda or Toyota implementation?

[fuzzybabybunny]

I thought these videos were excellent.

How Subaru's AWD system works:

https://youtu.be/Ny6AEPxLRC8

How SH-AWD works:

https://youtu.be/Yz9ol5zy5nk

Some key points:

Automatic Subarus are simply programmed to have their center differential clutch pack always engaged so power is always sent to the rear wheels. If the programming was changed it could easily be turned into a Honda/Toyota system that is 100% FWD in normal situations.

The SH-AWD system is superior to Subaru's system IMO, provided it has the right programming.

The regular Honda and Toyota AWD systems are simply programmed to not send much torque to the rear wheels, possibly to preserve the life of the light-duty center differential. IMO their system is useless. Not being able to make it up a 20% grade when both rear wheels have full traction is utterly pathetic. And the way the cars start to slide sideways downhill is dangerous at best in the hill climb video.

 

[Subyman]

Marketing!

Subarus use torsen limited slip differentials which means that if a single wheel goes airborne or looses all traction (ice), the entire system takes a dump and sends all the power to the wheel with no traction, which is the exact opposite of what you would want it to do. They are good in the snow with all four wheels grabbing something, but you can get stuck just trying to turn up a steep driveway in the dry.

https://www.youtube.com/watch?v=w4oAKOCRy9g

While older versions of Honda and Toyota's AWD systems have had varying levels of ability to react to front-wheel slippage in a timely manner and/or had limitations in torque distribution, Honda's current CR-V system is very advanced and will even send torque to the rear under normal, non-slip conditions to for the sole purpose of affecting suspension squat under acceleration. Pretty clever stuff. And that's not even getting into the SH-AWD torque vectoring magic stuff. Honda pioneered street-car active torque vectoring with the Prelude SH, years before Ferrari tried it.

The video of the CR-V not able to move up the incline with both front wheels on "ice" is a good case for real, lockable 4WD, but at least it takes two wheels on the same axle with no traction to strand a CR-V, instead of just one wheel anywhere for a Subaru.

Depends on the model and how it is equipped. Some models come with LSDs.

 

[Accord99]

the Audi looks like it could have made it though, the driver looks like he was hitting the brakes when it was gaining traction.

I'm not sure about that since the Audi kept on veering to the left when power was being applied and eventually leaving the iced section.