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Discussion Starter #1
I have been reading a lot on forums lately that the CVT AWD is FWD until needed then it sends some power to the rears. All of the "white papers" I see suggest it is 60% front and 40% rear "normally" (what I understand to be 0 slip coditions). Can anyone clarify this?

This site does not specify the "default front/rear distribution but says that up to 100% of power can be sent to rear.



Here is a page, which apparently used to explain the 60/40 split on the ATS AWD, but page no longer exists.


So I can't find any OFFICIAL page (not a dealer website, and not a 3rd party website) that references 60/40 normal split at this time. Can anyone help?
 

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2020 Ascent, 2011 WRX, 2001 Forester
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I always liked this guys video:

The CVT's you see which are FWD then go AWD with slip are NOT Subaru's....that's how other manufacturers claim AWD and its poor compared to Subaru's full-time AWD.

If you need actual Subaru documents beyond them saying "full-time active all-wheel-drive" then some others might have links to reference.
 

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Discussion Starter #3
I have seen that video and it is a good explanation. It would be nice to be armed with something official. There is a lot of misinformation being spread,

This is the best I have found, from subaru.ca:


This system employs a multi-plate transfer clutch that maintains a 60/40 front/rear torque split and uses a range of sensors to automatically adjust this split on-the-fly as conditions warrant, creating more predictable handling. The system that's linked to all Subaru models (excluding WRX) equipped with the Lineartronic® Continuously Variable Transmission (CVT), the Active Torque Split AWD places the focus on ease of operation, fuel efficiency and reliability.
 

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2021 Subaru Ascent Touring
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Discussion Starter #5
I also posed the question to subaru.com. I'd like to know the max available power that can go to either axle.
 

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The document starts boasting about LSDs and their "magic"
"Unlike other all-wheel drive systems, Subaru integrates its transfer case into the transmission, as opposed to a front wheel bias. The use of limited slip differentials (LSD) is key, as they combine the benefits of open and locked differentials. The torque split of a LSD is based on available grip, and makes it a great choice for daily driving."
and then tells - the diffs are open :)
"Active Torque Split (ATS)
The next most popular option is the Active Torque Split system. Included on all continuously variable transmission (CVT) models like the Forester, Legacy and Outback, this option splits torque in a 60/40 ratio between the front and rear wheels. This AWD system includes a multi-plate center clutch, not a differential, but does have an open differential in the front and rear like in the VCD engine. It is called an Active system because unlike other AWD systems, it doesn't wait for loss of traction to engage, so there's no delay."

Basically, it confirms that our Subarus got mechanical part that is very similar to other crossovers ( like KIA Sorento). e.g.
no "magic". They claim, that it is different - I hope so. Software certainly should be different...

 

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I also posed the question to subaru.com. I'd like to know the max available power that can go to either axle.
I believe the answer to that question is 100%. Here's an exerpt about the ATS AWD system:

An electronically managed continuously variable transfer clutch actively manages torque distribution in response to driving conditions, acceleration, deceleration and cornering. Slippage at the front or rear wheels causes torque to transfer (up to 100%) to the opposite set of wheels.

----------------------------------------

This type of question comes up a lot and the replies are always a mixed bag of facts and misinformation. Can we get a definitive sticky for this? It is fairly confusing, but I think Engineering Explained has one of the best explanations out there. Our Ascents are always in AWD by default (seems to be 60/40) and that can change instantaneously.

The Kia Sorento system, like many FWD based AWD systems out there is 100% FWD by default. Apparently this applies to 2011-2021.

 

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Discussion Starter #8
The document starts boasting about LSDs and their "magic"
"Unlike other all-wheel drive systems, Subaru integrates its transfer case into the transmission, as opposed to a front wheel bias. The use of limited slip differentials (LSD) is key, as they combine the benefits of open and locked differentials. The torque split of a LSD is based on available grip, and makes it a great choice for daily driving."
and then tells - the diffs are open :)
"Active Torque Split (ATS)
The next most popular option is the Active Torque Split system. Included on all continuously variable transmission (CVT) models like the Forester, Legacy and Outback, this option splits torque in a 60/40 ratio between the front and rear wheels. This AWD system includes a multi-plate center clutch, not a differential, but does have an open differential in the front and rear like in the VCD engine. It is called an Active system because unlike other AWD systems, it doesn't wait for loss of traction to engage, so there's no delay."

Basically, it confirms that our Subarus got mechanical part that is very similar to other crossovers ( like KIA Sorento). e.g.
no "magic". They claim, that it is different - I hope so. Software certainly should be different...


I think most of the mid price range cross overs are FWD by default which is one major difference if Subaru is sending 40% to the rear by default.
 

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The information shouldn't be so hard to find, but I'm not having much luck. I believe the ascent has a rear bias not front, so its probably a form of the VTD system such as is used on the WRX cvt since its a variant of that cvt. I'm sure @Robert.Mauro has the links or brochures with the info.

None of Subarus awd systems are on demand, they are all awd all the time.
 

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Hi Ruben Marin and pcampbell

The Ascent does not come with VTD, it uses Active Torque Split. What I find interesting is the link to Subaru USA's media page provided by pcampbell is a typo listing the 2015 WRX CVT as using ATS when it is really using the VTD system.

Also pcampbell is right, the Subaru global site has been reworked and Subaru looks like it is now putting less emphasis on AWD and more on responsible technologies (i.e. safety systems and environmental systems).

But there is a some interesting reads from revised Subaru global site...

Don't click on the English language version in the upper right corner as there is no information (unless you plan on being an investor) . Instead turn on Google Translate and read the Japanese version of the website. There some good stuff on Subaru's hybrid philosophy:
誰もがクルマを愉しめる未来を⽬指して – 知能化技術の活⽤で「SUBARU」らしさを極める | 株式会社SUBARU(スバル)
 

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Discussion Starter #15
The document starts boasting about LSDs and their "magic"
"Unlike other all-wheel drive systems, Subaru integrates its transfer case into the transmission, as opposed to a front wheel bias. The use of limited slip differentials (LSD) is key, as they combine the benefits of open and locked differentials. The torque split of a LSD is based on available grip, and makes it a great choice for daily driving."
and then tells - the diffs are open :)
"Active Torque Split (ATS)
The next most popular option is the Active Torque Split system. Included on all continuously variable transmission (CVT) models like the Forester, Legacy and Outback, this option splits torque in a 60/40 ratio between the front and rear wheels. This AWD system includes a multi-plate center clutch, not a differential, but does have an open differential in the front and rear like in the VCD engine. It is called an Active system because unlike other AWD systems, it doesn't wait for loss of traction to engage, so there's no delay."

Basically, it confirms that our Subarus got mechanical part that is very similar to other crossovers ( like KIA Sorento). e.g.
no "magic". They claim, that it is different - I hope so. Software certainly should be different...

I don't really trust the dealer websites because I think a lot of these are modified by the dealer employees perhaps. The reason I say that is because a lot of them vary slightly, and none of the text I find on dealer websites matches what I can find on subaru.com official literature.
 

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The document starts boasting about LSDs and their "magic"
"Unlike other all-wheel drive systems, Subaru integrates its transfer case into the transmission, as opposed to a front wheel bias. The use of limited slip differentials (LSD) is key, as they combine the benefits of open and locked differentials. The torque split of a LSD is based on available grip, and makes it a great choice for daily driving."
and then tells - the diffs are open :)
"Active Torque Split (ATS)
The next most popular option is the Active Torque Split system. Included on all continuously variable transmission (CVT) models like the Forester, Legacy and Outback, this option splits torque in a 60/40 ratio between the front and rear wheels. This AWD system includes a multi-plate center clutch, not a differential, but does have an open differential in the front and rear like in the VCD engine. It is called an Active system because unlike other AWD systems, it doesn't wait for loss of traction to engage, so there's no delay."

Basically, it confirms that our Subarus got mechanical part that is very similar to other crossovers ( like KIA Sorento). e.g.
no "magic". They claim, that it is different - I hope so. Software certainly should be different...

No, it's considerably different, and here's how.
  1. Front differential is inside the CVT (and manuals), with zero directional changes (one shaft goes to the front differential, and in the opposite direction, the output shaft goes to the rear differential). There's no 2, 3, or 4 90° turns. There's no separate gear box. That allows more power to be transmitted to the wheels, less stress points in the drivetrain, and easier ability to control where power goes.
  2. The system is designed to put higher amounts of power to the rear end continuously (and we have a beefy rear end designed to handle it - even beefier in the Premium, Limited and Touring). Honda, for instance, does not, because their system is a part time system. People who decided to push the system, forcing it to be engaged for a little more than their "part time" plans, ended up with burned out rear differentials. Honda's solution to that was to have the computer limit power to the rear even more.
  3. Subaru's system is symmetrical. That means the system isn't fighting torque steer like all the rest. Instead, it only has AWD chores to deal with. It makes it more able to deal with shuttling power to retain tire grip, and, because it's ALWAYS on AWD, proactive in helping prevent vectoring based slip from ever starting.
  4. Subaru's system is ALWAYS on. While systems like Nissan's are 100% front, 0% rear for most driving, and Hyundai's are 80-100% front, 20-0% rear, Subaru's is 60/40 under normal driving. Anyone who's driven on the beach with a 2WD/4WD vehicle knows that the same amount of power that makes a 4WD vehicle move, can be the same amount of power to make that same vehicle spin wheels in 2WD mode. NOT breaking grip is considerably better than losing grip and a system trying to correct it.
  5. Subaru has spent decades building and learning how to make what's arguably one of the best AWD systems on the market, while most other systems are 2WD systems with tacked on components to shuttle some power to the rear.
And in the case of our TR690, there's more. Besides the chain based CVT nature of the system, we don't have the normal collection of gears. We've got primary and secondary reduction gears, a transfer gear, and that's virtually it. Heck, even forward and reverse are not done with gears. Power transfer from engine to differentials is very simple with very few parts.

There's a reason Subaru's system continuously beats the rest in test after test. For instance, other cars do flat ground roller tests, Subarus get tested on inclines.

Jason at Engineering Explained does a good job explaining Subaru's current four AWD systems. TR690 based configurations (eg: WRX automatic, Ascent, OB XT) come in two configurations.

Hyundai likes to think they have one of the best systems, but, truthfully, they've got nothing special, expect in advertising-speak. Watch 16m20s mark.... and remember this horrible performance with the Telluride, for when you get to the last video.


Compare to the Ascent driving up a far steeper incline, coming to a near dead stop, then powering up and over with ease (2m20s, 7m,26s)



Or to this (3m48s, 7m40s)...

https://youtu.be/jt8vm9BXViU?t=461

OR, Ryan doing the same trail with the Ascent (as he did with the Telluride), except in the snow (10m58).

All AWD systems are not equal. Not even remotely.
 

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Discussion Starter #17
Just adding a little fuel... in this video he says 80/20 under normal circumstances, and says that the info was confirmed with Subaru engineers.


 

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Just adding a little fuel... in this video he says 80/20 under normal circumstances, and says that the info was confirmed with Subaru engineers.


Ryan is incorrect. He and I discussed this after the video was made. Subaru's old systems started at 90/10, then progressed to 80/20, and now finally 60/40 since 2009. Subaru's engineers have confirmed that, countless times.


This quote is from Subaru Global's AWD page from 2012, which is no longer up. FHI (now "Subaru Corp") in Japan is who designed and makes the TR690, TR580 and our AWD system.

6756
 

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Discussion Starter #19
Ryan is incorrect. He and I discussed this after the video was made. Subaru's old systems started at 90/10, then progressed to 80/20, and now finally 60/40 since 2009. Subaru's engineers have confirmed that, countless times.


This quote is from Subaru Global's AWD page from 2012, which is no longer up. FHI (now "Subaru Corp") in Japan is who designed and makes the TR690, TR580 and our AWD system.

View attachment 6756
Thanks, the still-up canada.ca website has similar info as the Fuji site used to display, with the 60/40 split info.
 

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@Robert.Mauro what WAS that clunk in the 3rd video at 5:14?
I have to say the palisade just looks out of its element on a bumpy gravel road. I'm sure their engineers are correct that its designed for a wheel to spin like that but it certainly doesnt make that a better system lol
 
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