Overview of AWD Systems

Not all Audi's have Torsen, the top tier do.
And even quattro/4Motion branding is confusing. From what I understand, MLB/B-platform based Audi/VWs will use a ZF transmission with an integrated Torsen center diff and a front diff with AWD. MQB/A-platform cars with AWD will use a PTO and a Haldex(now Borg-Warner) or GKN AWD system. Honda, Subaru and maybe Toyota developed their AWD systems in-house, with Honda using Borg-Warner for VTM-4/SH-AWD and Toyota using in-house or BW transfer cases on their trucks. GKN and BW/Haldex are to thank for everyone else.
 
Not all Audi's have Torsen, the top tier do.
Transverse engine are Haldex. Longitudinal are Torsen.

I have one of each! 2003 VW Passat W8 wagon has Torsen. 2018 VW Golf Sportwagen has Haldex.
 
Haldex Gen 5 slow-mo snow launch. The "it only works when the front wheel slips" is not accurate. I have logged mine many times while driving (Haldex clutch activity) and it's basically active any time you give it gas. Obviously this will vary on need so front slip will increase this need and cruising will take it down to close to zero. I really like it...my wagon is v. sure-footed with traction for days on the street or track.



 
By contrast....Torsen (Quattro) in my W8 Passat wagon...four wheel snow donuts!

 
Also...folks always turn awd posts into a discussion about snow, snow tires, drivers, etc. I'll take an awd car (Haldex or otherwise) for dry or wet road performance driving any day.
 
Mitsubisi Monteros had super select 4x4, which was basically an ordinary transfer case (2h 4h 4l) but it had a viscous coupling of some sort and a awd position on the shifter. no traction control. awd worked pretty good and helped me climb some boulders. i always ran it in 2h, and eventually swapped the lockable awd case for a traditional case that was only part time AWD. the super select case had 2h, 4h, (same as awd) and 4h lock and 4l lock were solid center dif.

jeep grand Cherokee 2006 has an awd center dif that isn't just clutches but it's advertised as true 4x4 and I don't think it locks so it's just a good awd system IMO. old Chevy trucks have 4x4 that is a normal transfer case and then electronic clutches to the front driveshaft so if you get stuck and the clutches slip you only have rwd.
 
Also...folks always turn awd posts into a discussion about snow, snow tires, drivers, etc. I'll take an awd car (Haldex or otherwise) for dry or wet road performance driving any day.
I would own an AWD performance car if I lived in the desert. So many corners my AWD pushes me through corners, even in a fwd bias car, or it lets me be far more confident at nearing the limit. Rain swept corners having all four corners laying down power allows for more traction over all because a tire can only grip 100% and if a fwd car has to put power down and steer you lack in both.If a rwd. car has to put down 100% power down in a rain swept corner it will allow too easy of an oversteer situation.
 
Not all Audi's have Torsen, the top tier do.
The Modern Audi's used Torsen, until they shared platforms with the VW Golf, then Haldex was introduced, something as low as A4 had Torsen for a long time, starting at the B5 generation.

But Torsen died out, and replaced by Audi's own Crown Gear Differential.

And, to chase fuel economy, partnering with Magna, came Ultra Technology which worked like a Haldex on a longitudinal chassis, including the rear axle disconnect for full FWD for fuel efficiency, but can transfer more torque to the rear than Haldex.
 
Nope:




Most AWD drives suck if you need them the most. Unless you got 3 locks, you are on your own.

That's 1st gen Highlander.

The highlanders are explained here until the 2020+

As the 2020+ on higher end trims (XSE, Limited and Platinum) had 2 additional clutches on the rear axle for torque vectoring.

Go to about 9:00 and she will trigger the Subaru faithful
 
The S-AWC in the Evo has a pretty complex AWD system and is still probably one of the most advanced AWDs you can get in a road legal car now. It's super fun to read about and when I left the scene in 2015, the only ones who were able to adjust [tune] the S-AWC was Bosch with their own unit, requiring you renting out an entire track for the day and paying for the services which if I recall correctly, started no lower than $20,000. I don't think that has changed.

  • 3 hydraulic diffs: front, center, rear. All functionally open diffs. The center and rear diffs are active.
  • System is always 50:50 front/rear power split
  • 3 known sensor inputs: wheel speed, yaw sensor, and steering angle sensor
  • When the power starts to bias towards front/rear more than the other, the center diff will start locking
  • The rear diff can send 100% of it's given power to either side - so essentially up to 50% of the car's total power can be sent to either rear wheels (torque vectoring, also known as AYC-active yaw control for Mitsu.)
  • There are 3 AWD settings, tarmac, gravel, snow.
    • Tarmac allows the center diff to stay open the longest but will clamp the hardest once limits are reached
    • Snow will lock the center diff the earliest but the clamping force is much more gradual than tarmac, essentially allowing smoother locking operations. This was a favorite with drag racers.
    • Gravel is in the middle. Usually this was also a favorite when racing in wet conditions.
  • The traction control and stability had 3 settings.
    • Completely on - TC will disable engine power (horrific feeling I might add.) SC will operate the rear brakes as a way to help the rear rotate.
    • TC off, SC on
    • TC and SC off. Recommended for the track as leaving SC on will burn up the rear brakes

- Fun fact: There were high failure rates for the pump due to corrosion. The pump for the system was located behind the passenger rear wheel covered by nothing more than the body panel and wheel liner. If you lived in the salt belt, it wasn't a matter of if your pump failed but when and often before the car reaches 100K.

I realize I'm replying to post from two years ago but I just want to say Mitsubishi's S-AWC is heavily underrated by A LOT of people as they don't want to take the time to read and understand how it works. It is by far one of the best in the world. S-AWC still lives on in the Outlander but only on the front wheels and not the rear.
 
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I believe many AWD models are the equal of Subaru these days. The CRV is not one of those..lol
I doubt any are better though
 
I believe many AWD models are the equal of Subaru these days. The CRV is not one of those..lol
I doubt any are better though
Subaru sells a lot of AWD. Cheaply.

Doesn’t mean that what they sell is the best, or even good.

McDonalds sells a lot of burgers. Cheaply.

But there are better burgers.
 
Subaru sells a lot of AWD. Cheaply.

Doesn’t mean that what they sell is the best, or even good.

McDonalds sells a lot of burgers. Cheaply.

But there are better burgers.
Well I would not keep buying them (on my 5th) if I didn't feel they were the best value for the Dollar. Just take safety. They have ALWAYS been up front. The year the small overlap test came out ALL their carlines passed. Very few vehicles let alone ALL carlines of a brand of vehicles passed.. Their Global Platform, that they invested a billion$ on is supposedly an improvement. I can't say that its true.
 
Well I would not keep buying them (on my 5th) if I didn't feel they were the best value for the Dollar. Just take safety. They have ALWAYS been up front. The year the small overlap test came out ALL their carlines passed. Very few vehicles let alone ALL carlines of a brand of vehicles passed.. Their Global Platform, that they invested a billion$ on is supposedly an improvement. I can't say that its true.
They’re a great value. I’m sorry, I should’ve said that.

I just don’t think they have the best AWD system.

I should‘ve been more clear, and, frankly, more positive. Subaru makes a very good car. I’ve recommended them to others. I think you’ve made a good choice.

My previous post was unreasonable. I apologize.
 
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