AWD Systems / Technologies Differences between Subaru and Toyota and Honda

[Ogg]

I'm curious about how other manufacturers AWD systems work(Mazda, Hyundai/Kia, GM, Ford etc.) It seems there is even less information available about those systems than Toyota and Honda. Subaru seems to be pretty open(proud?) about their tech. Other manufacturers seem willfully vague.

 

[François Pugh]

 

[François Pugh]

BTW, something folks seem to have forgotten from back in the day when "rocking" your car was a thing,
It takes torque to increase the rotation speed of a wheel. Useful to know if you have open diffs, or a system that makes torque on the traction wheel 4 or whatever times that on the slipping wheel (4 x 0 =0), provided you can turn off the traction control and spin up that slipping wheel. It only works when the wheel is increasing in rotation al speed.

Also applying brakes ( using a bit of parking brake in your old beater with open diffs. used to be a trick) provides a means of making that torque non-zero.

Of course these "tricks" have their limitations and costs.

 

[cantunamunch]

provided you can turn off the traction control

All of these AWD threads are incomplete without traction and stability control discussion. Case in point: the understeer to oversteer change situation @scott43 describes above absolutely triggers Honda VSA.

 

[scott43]

I'm curious about how other manufacturers AWD systems work(Mazda, Hyundai/Kia, GM, Ford etc.) It seems there is even less information available about those systems than Toyota and Honda. Subaru seems to be pretty open(proud?) about their tech. Other manufacturers seem willfully vague.

I don't think most people care. The AWD systems are practically invisible to the drivers and that's what they want. Couple that with the ABS, Vehicle Stability Control and really for 99% of their buyers, they're good to go. Subaru's shtick is the full-time symmetrical all wheel drive..and they are nice systems..but..for most people, they won't notice. I like to ask people if they read the owners manual of their vehicle. Most people by a large margin don't. They couldn't care less what AWD system is in their car or how it works. They just want french fries at 1am in a snow storm and as long as they get there, they're happy.

 

[scott43]

All of these AWD threads are incomplete without traction and stability control discussion. Case in point: the understeer to oversteer change situation @scott43 describes above absolutely triggers Honda VSA.

Those systems do not like differing wheel speeds or any yaw rate..and they're pretty good at getting rid of it.

 

[Dwight]

I have Lexus Rx350 and Subaru Impreza Sport. Both 2008s. In snow, have fun keeping up with me in the Subarau. Tires are fairly equal too.

 

[cantunamunch]

Those systems do not like differing wheel speeds or any yaw rate..and they're pretty good at getting rid of it.

A lot of them do body roll now too. As to how all that is weighted

 

[scott43]

A lot of them do body roll now too. As to how all that is weighted

Et voila. Le black box!

 

[Wilhelmson]

I have Lexus Rx350 and Subaru Impreza Sport. Both 2008s. In snow, have fun keeping up with me in the Subarau. Tires are fairly equal too.

About 20 threads ago it was decided that awd is pointless since going over 30 mph is dangerous and an aged 2wd truck with mismatched snow tires is the ultimate snow machine in the hands a capable driver.

 

[Snowfan]

Not sure why the link looks like Subie main...it actually goes to their awd info page.

Subaru: Go Where the Love Takes You

Love. It's what makes Subaru, Subaru.

www.subaru.com

 

[Philpug]

I have had about 20 AWD cars from Audi, VW, and Subaru...our current Alltrack is the best one I have driven.

 

[Dwight]

About 20 threads ago it was decided that awd is pointless since going over 30 mph is dangerous and an aged 2wd truck with mismatched snow tires is the ultimate snow machine in the hands a capable driver.

Yep, did that for years too. Talking to tow truck drivers here, they bail out more 4wd trucks than 2wd drive trucks.

 

[Andy Mink]

One of the biggest drawbacks with at least some of the Subaru systems is the need for tires that are within a small percentage of each other in diameter. Three good tires halfway through their life and one unrepairable flat? Four new tires.

 

[Ogg]

One of the biggest drawbacks with at least some of the Subaru systems is the need for tires that are within a small percentage of each other in diameter. Three good tires halfway through their life and one unrepairable flat? Four new tires.

This is something I do point out to anyone I know considering their first AWD car. I know my wife's boss was kind of shocked first time he got a flat in his A8.

 

[scott43]

One of the biggest drawbacks with at least some of the Subaru systems is the need for tires that are within a small percentage of each other in diameter. Three good tires halfway through their life and one unrepairable flat? Four new tires.

On the plus side, the tires wear almost exactly equally. But you make a good point.

 

[Philpug]

I believe the tire issue is the same with most AWD systems.

 

[dbostedo]

Yep, did that for years too. Talking to tow truck drivers here, they bail out more 4wd trucks than 2wd drive trucks.

If it's anything like here, that's because 4WD/AWD owners think that they have the the ability to drive as if there's no snow or ice, just because they have 4WD/AWD. I still remember driving down the snowy highway here in my little 2WD VW not long after I moved here, and seeing a Ford Expedition and a Cadillac Escalade crashed and locked together grill-to-grill off the side of the highway.

 

[Uncle-A]

I'm curious about how other manufacturers AWD systems work(Mazda, Hyundai/Kia, GM, Ford etc.) It seems there is even less information available about those systems than Toyota and Honda. Subaru seems to be pretty open(proud?) about their tech. Other manufacturers seem willfully vague.

I am curious about how they compair to Jeep 4 X 4?

 

[scott43]

I am curious about how they compair to Jeep 4 X 4?

Which Jeep 4x4.. they have multiple systems as well .