What type of AWD system does the G70 use?

[Toddasaurus]

Okay, dug into things a bit more and this is what I found.

Magna supplies the hardware for some of Audi's applications, BMW, and Hyundai.

From what I can see, Magna designed a transfer case known as ActiMax. This has been used in most BMW's X-Drive systems, but last year (2017) they developed a new transfer case called EcoMax. The difference is that EcoMax is able to completely disable/disconnect the front wheels from the driveline, whereas the ActiMax transfer case is always connected to all four wheels, though it is able to shift the torque between front and rear up to 100% - however, the details of this are a bit sketchy. Evidently there is still some parasitic drag in place when this is occurring, as there is still some hardware spinning despite all the torque being shifted around. EcoMax is able to remove that drag during 2WD operation. Another feature is that it uses less gear oil than the ActiMax (10oz vs 24oz), as the EcoMax uses a dry clutch instead of a wet clutch, which removes even more drag during cruising. The new design improves fuel economy up to 4%.

Some of Audi's Quattro applications use a Magna supplied coupling, but only used in their cars that have a longitudinally positioned engine (transverse uses HALDEX). This system is called Flex4. Flex4 is able to completely disconnect the rear wheels, effectively making it a FWD vehicle; however, EcoMax disconnects the front two wheels instead. Since Flex4 refers to just the coupling, it is also used in EcoMax. Response times should be the same between Audi and BMW. The Flex4 coupling is advertised as taking 0.3 seconds to switch from 2WD mode to AWD mode and vise versa.

I am unsure about the weight of each of these systems.

HTRAC, sounds like a variation of ActiMax. Specifically, "The system deploys a newly developed right-hand drop version of Magna Powertrain's active transfer case, which enabled Hyundai to overcome challenging underbody packaging constraints." There is no mention of the system being able to completely disconnect from the front or rear wheels, thus may not be as efficient as Flex4/EcoMax. I don't know what style of clutch is used in the HTRAC's transfer case, but it is advertised as weighing "only 61kg." Again, I'm not sure if this is lighter than the other systems, but the articles I've read almost seem to imply that it's smaller and lighter...


Considering the above information, I gotta admit I was wrong. It sounds like HTRAC is essentially the same as last year's X-Drive, but the transfer case just may be lighter, smaller, and shaped differently; but, it works exactly the same.

[Edit: got some of my facts wrong, fixed now.]



[References:]
Why Hyundai has different AWD systems for different vehicles - Autofocus.ca
Magna AWD System Helps Hyundai Genesis Achieve New Levels of Driving Performance
Magna Connects With Disconnecting Axles

 

[PD705]

Close but not quite. HTRAC has had the capability of the "EcoMax" transfer case since its launch in the 2015 Hyundai Genesis. It has always had the capability of disconnecting the front driveshaft for fuel efficiency in steady highway cruising, even before this was added to BMW models. Further, in G70 the system was updated yet again, with different torque splits (default 50/50 off the line vs. 40/60, higher RWD bias) and the ability to go 100% RWD in select high-performance driving conditions.

 

[Beefer]

Close but not quite. HTRAC has had the capability of the "EcoMax" transfer case since its launch in the 2015 Hyundai Genesis. It has always had the capability of disconnecting the front driveshaft for fuel efficiency in steady highway cruising, even before this was added to BMW models. Further, in G70 the system was updated yet again, with different torque splits (default 50/50 off the line vs. 40/60, higher RWD bias) and the ability to go 100% RWD in select high-performance driving conditions.

I thought the best the G70 can do is 10/90?

 

[Toddasaurus]

Close but not quite. HTRAC has had the capability of the "EcoMax" transfer case since its launch in the 2015 Hyundai Genesis. It has always had the capability of disconnecting the front driveshaft for fuel efficiency in steady highway cruising, even before this was added to BMW models. Further, in G70 the system was updated yet again, with different torque splits (default 50/50 off the line vs. 40/60, higher RWD bias) and the ability to go 100% RWD in select high-performance driving conditions.

Like I said above, the ActiMax transfer case has the capability of applying 100% torque to the rear, it sounds like it just depends on the software, which I'm sure is different between BMW's and Hyundai, and I bet it's even different on the Stinger compared to the G70. Again, both X-Drive and HTRAC are based on ActiMax. EcoMax, as far as I know, is only used in the new BMW X3, where (I assume) they don't care as much about all-out performance. Personally, I'd rather not have that 0.3 seconds of delay for it to switch from 2WD to AWD while driving. But, maybe this wouldn't apply in something like sport mode..?

Can you show me where you got the info stating HTRAC can completely disconnect the front drive line? I'm not doubting you, I just couldn't find anything specifically clarifying that. There are definitely gaps in the information I've found so far.



Edit: dug up a bit more info, but still no real new information... Nor can I find anything specific to the G70. :c

Found more articles about HTRAC, this one states...

To maximize efficiency, the system directs available torque to the rear wheels during steady-state highway cruising, improving fuel economy and NVH.

Magna AWD System Helps Hyundai Genesis Achieve New Levels AUTO MOTORES

It doesn't specifically state that the front wheels/drivetrain actually disconnects from the transfer case.



Another article mentions variations on torque split, depending on driving mode....

In Normal, torque split is 40:60 front to rear, which is also the default setting. In slippery conditions, 90 per cent of torque goes to the front wheels or up to 100 per cent to the rear wheels at higher speeds. When climbing hills, the torque split is 30:60.

Switch to Sport and the system sends torque back and forth as required to counteract under or oversteer. That split can vary from 20:80 to 10:90 per cent.

2015 Hyundai Genesis AWD Review – WHEELS.ca

....but again, doesn't clarify if it actually has a disconnect coupling. Though "100% to the rear wheels" almost implies such a thing!

 

[YEH]

It was named HTRAC when the 2015 Hyundai Genesis (DH generation) launched, and it was unique to that vehicle. Only recently did Hyundai adopt HTRAC for their mechanically-different system. Genesis will transition to a different name in the near future.

Yeah, previously Hyundai was using a Haldex system (assuming their new HTRAC is also being sourced from Magna).

 

[g_315712]

Magna also makes the 4matic system for Benz

 

[NLJ]

I thought the best the G70 can do is 10/90?

If you have the AR app, check out the Canadian Brochure on the Htrac.
Apparently on Comfort mode, it can decouple entirely for 0:100 for fuel savings.
On Sport, it always maintains AWD in varying torque splits for maximum performance. But mostly 20:80 and 10:90.
In slippery conditions, it can do 80:20 to pull you out.
In off-road and non pavement rough surfaces, it will maintain a 50:50 split.

 

[Slip_Angle]

Got this in an email from Genesis Canada...

 

[NLJ]

Got this in an email from Genesis Canada...

View attachment 16883

That's pretty cryptic. What does Normal mean?
Also there is no way it can send 100% to the front unless it has an active front differential. Even then it is impossible cause the power has to be routed from the back since it is not a transaxle!

 

[Toddasaurus]

That's pretty cryptic. What does Normal mean?
Also there is no way it can send 100% to the front unless it has an active front differential. Even then it is impossible cause the power has to be routed from the back since it is not a transaxle!

I agree, they could've made this more clear. Hah. I assume "Normal" means anything but Sport (ie comfort, eco, etc)...?

Some food for thought, the Magna transfer case is seated between the propshaft and the tranny. In theory it could completely disconnect the rear wheels, or the front wheels, and route power accordingly. This slide certainly makes it look like it might do just that. Eco mode (or F/E mode, I think?) looks like it sends all the power to the rear if you're just cruising. And likewise, escape mode (I think engaged when rear wheels are slipping badly) the front wheels take all the power...

All of this confirms what you and @PD705 have been saying all along!!

This is an awesome find. Thanks!

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[NLJ]

 

[EdP]

That's pretty cryptic. What does Normal mean?
Also there is no way it can send 100% to the front unless it has an active front differential. Even then it is impossible cause the power has to be routed from the back since it is not a transaxle!

That depends on your definition of 100%. There are power losses in the transfer through the systems so in reality, you are correct that it will never achieve 100%. OTOH if one set of wheels gets all available power and the other gets none, you can say it is getting 100% of available power after losses.

 

[NLJ]

That depends on your definition of 100%. There are power losses in the transfer through the systems so in reality, you are correct that it will never achieve 100%. OTOH if one set of wheels gets all available power and the other gets none, you can say it is getting 100% of available power after losses.

You can say that however that is inaccurate if you leave out "after losses", ESC, braking etc.
The Mazda guy on YouTube just did that with the Mazda 3 AWD saying 100% of the torque goes to the rear if the front has no grip!
What is really happening is that it get 100% of the torque split that is allowable to the rear wheel while the front is being braked. Basically just 50% of total torque cause the other 50% is slipping or being braked!
Now it is different if there are active differentials but that is not what we're talking about here.

 

[Slides]

You can say that however that is inaccurate if you leave out "after losses", ESC, braking etc.
The Mazda guy on YouTube just did that with the Mazda 3 AWD saying 100% of the torque goes to the rear if the front has no grip!
What is really happening is that it get 100% of the torque split that is allowable to the rear wheel while the front is being braked. Basically just 50% of total torque cause the other 50% is slipping or being braked!
Now it is different if there are active differentials but that is not what we're talking about here.

Does any car in this class have an "active" differential for front and rear? I have an Audi S5 Quattro (torsen) with the sports rear differential and I'm not sure if even it has this active front to rear differential. It does have an active left to right rear differential though.

That's my understanding anyways. Not an expert.

 

[NLJ]

Does any car in this class have an "active" differential for front and rear? I have an Audi S5 Quattro (torsen) with the sports rear differential and I'm not sure if even it has this active front to rear differential. It does have an active left to right rear differential though.

That's my understanding anyways. Not an expert.

That's an Active Rear Differential. Ala SH-AWD.
Mitsubishi has an Active Front Differential on the Outlander XLS/GT S-AWC from 2007-2013. Not sure about the generation after that since they diluted the S-AWC term. Mitsubishi also had an Active Rear Differential on the EVO called S-AYC and an Active Center Differential which they didn't give a name to and just called ACD.
Their ACD was a lot more sophisticated than other FWD based AWD systems. I believe the STI had a pretty sophisticated ACD as well which allowed you to manually set the front to rear distribution!

 

[Slides]

That's an Active Rear Differential. Ala SH-AWD.
Mitsubishi has an Active Front Differential on the Outlander XLS/GT S-AWC from 2007-2013. Not sure about the generation after that since they diluted the S-AWC term. Mitsubishi also had an Active Rear Differential on the EVO called S-AYC and an Active Center Differential which they didn't give a name to and just called ACD.
Their ACD was a lot more sophisticated than other FWD based AWD systems. I believe the STI had a pretty sophisticated ACD as well which allowed you to manually set the front to rear distribution!

Yeah, that's what I meant. The rear differential on my S5 is superior to the LSD, but the front and rear distribution on the G70 seems to be fairly standard for it's class in the entry luxury sedan segment. Especially the Germans.

Mitsubishis aren't not exactly luxury cars though.

 

[Toddasaurus]

View attachment 16895View attachment 16896View attachment 16897View attachment 16898View attachment 16899View attachment 16900View attachment 16902

I'm right there with you, but just trying to make sense of the slide that @Slip_Angle posted.. The pics you posted, as far as I understand, are for HTRAC in general. There is a possibility that the G70 has a revised version of it, allowing said configurations to take place? Maybe? To me, it seems like the Magna supplied transfer case should be able to do it. In fact, Magna themselves state that the ActiMax transfer case can apply 100% of torque to either the front or rear end of the drivetrain. It uses an electronically controlled wet clutch to do this.

Does any car in this class have an "active" differential for front and rear? I have an Audi S5 Quattro (torsen) with the sports rear differential and I'm not sure if even it has this active front to rear differential. It does have an active left to right rear differential though.

That's my understanding anyways. Not an expert.

I'm no expert either, but I have done a lot of work on cars, including AWD cars - but still, not an expert. According to the articles I found in my first post of this thread there are some Audi and BMW models that use a system (be it transfer case or coupling) that can completely disconnect the front and/or rear wheels for fuel economy. I'm not exactly sure which models have said systems, though.

 

[Slides]

I'm no expert either, but I have done a lot of work on cars, including AWD cars - but still, not an expert. According to the articles I found in my first post of this thread there are some Audi and BMW models that use a system (be it transfer case or coupling) that can completely disconnect the front and/or rear wheels for fuel economy. I'm not exactly sure which models have said systems, though.

Looking through what I know from my Audi S5, I don't think the torsen differential can do 100%-0% split. It will be interesting to know what the real split is for the Hyundai/Genesis system.

 

[Toddasaurus]

Looking through what I know from my Audi S5, I don't think the torsen differential can do 100%-0% split. It will be interesting to know what the real split is for the Hyundai/Genesis system.

You're right - torsen, or any mechanical helical type differential is always going to be sending some power in both directions. Engineering Explained on YouTube gives a really helpful explanation of how it all works, but it can still be hard to visualize.

 

[Toddasaurus]

That's an Active Rear Differential. Ala SH-AWD.
Mitsubishi has an Active Front Differential on the Outlander XLS/GT S-AWC from 2007-2013. Not sure about the generation after that since they diluted the S-AWC term. Mitsubishi also had an Active Rear Differential on the EVO called S-AYC and an Active Center Differential which they didn't give a name to and just called ACD.
Their ACD was a lot more sophisticated than other FWD based AWD systems. I believe the STI had a pretty sophisticated ACD as well which allowed you to manually set the front to rear distribution!

A lot of that is just advertising, unfortunately. Not all of those systems are created equal. Some brake-based torque vectoring systems have the words "active" in it, despite being inferior to a clutch type system.

The WRX STi's center diff is essentially an electronically controlled clutch type coupling mated to a mechanical LSD. This allows their software to control some of the power transfer between front and rear, but it is unable to send all the power in either direction, as even if the clutch is fully locked the mechanical differential will still allow for some slip (ie front or rear wheels to spin at slightly different speeds, relative to each other).

Hyundai's HTRAC is different. The power is sent through a transfer case, which acts more like a welded differential (ie running fully locked), but it has an elaborate electronically controlled clutch system that allows all power to be sent it either direction, or even a perfect 50/50 distribution. The difference here is that it is ALL electronically controlled, there is NO mechanical differential or passive power transfer dictated by a differential - every bit of power transfer is controlled by the computer. Nothing analog about it.