Toyota GR Corolla Forum - Release Date, Specs, Pricing Discussion banner
121 - 140 of 158 Posts

·
Super Moderator
Joined
·
414 Posts
Any way to data log and pull voltage on the coupling during normal driving? That would a) validate that it’s full time and b) I’m curious how much it varies during normal driving to allow turning without bind (since it has to act as the center differential)
A quick google search will also tell you it's full time AWD. Second result when searching "gr yaris full time awd"

I don't fully understand it, but my initial understanding is that it replaces a center diff with multiple clutch packs that allow it to modulate front to pack power, so it can adjust on the fly, alongside the front and rear diffs, to allow wheels to spin slower or faster
 

·
Registered
Joined
·
63 Posts
I own the GR Yaris. I know my own car. It's permanent AWD. That's why it annihilates anything that uses Haldex in the corners, Golf R's, RS3's etc... It's permanent AWD system is the reason it can achieve better track times than much more powerful cars, that can only make their time back up on the straights, and also why the GR dominates in Australian rally. You'd not get far in rally against Evo's, Impreza's if your car was reverting to a FWD all the time.
Well TimeRacer is saying its always AWD, but its actually 95/5 torque split (or thereabouts). Only when losing traction does it go 60/40, 50/50, 30/70…
 

·
Registered
Joined
·
101 Posts
Discussion Starter · #123 ·
A quick google search will also tell you it's full time AWD. Second result when searching "gr yaris full time awd"

I don't fully understand it, but my initial understanding is that it replaces a center diff with multiple clutch packs that allow it to modulate front to pack power, so it can adjust on the fly, alongside the front and rear diffs, to allow wheels to spin slower or faster
I included that link in the original post and thesre has been discussion as to how accurate that is.
 

·
Registered
Joined
·
55 Posts
I own the GR Yaris. I know my own car. It's permanent AWD. That's why it annihilates anything that uses Haldex in the corners, Golf R's, RS3's etc... It's permanent AWD system is the reason it can achieve better track times than much more powerful cars, that can only make their time back up on the straights, and also why the GR dominates in Australian rally. You'd not get far in rally against Evo's, Impreza's if your car was reverting to a FWD all the time.
1) Your GR Yaris isn't permanent AWD. In fact it has a mode programmed into the computer to go into 2WD mode when the rear clutchpack temps rise at the track. It's inherent to any clutch based system as they're not physically connected when the clutch plate isn't squeezed. In a center differential system, the rear drive is permanently attached.

2) Not sure why it's so difficult to understand the difference between static split AWD and full time AWD. No one has said it's not full time AWD. Just doesn't bias anywhere near 40% to the rear all the time. If it did, the system would be trying to crush the car all the time and destroying the rear tires all the time due to the overdrive gear trying to spin the rear tires faster than the front. With any torque that can't be dissipated through the tires due to the tire grip must be converted to heat in the clutch pack which will fry it with at a minimum of 40% of all power always going to the rear in a static split.

3) Every AWD system available with an overdrive gear constantly adjusts the power going around the system. Be it GKN Twinsters or Type SH-AWD the rear only receives full squeeze down on the clutch pack after the front sensors have detected slip.Type-SH AWD specifically states cruising defaults to 95/5 split for not only gas mileage (static split AWD has terrible gas mileage as shown by Subaru) but for the service life of the rear clutchpack.

4) The Toyota supported Rally car isn't the same engine or drivetrain as your GR Yaris. Don't use it as a terrible comparison point of "it can't do ____ if it reverts to FWD" BTW the Evo reverts to FWD during mid turn as the rears travel a shorter circle in any given turn and why the Subaru WRX always understeers.

5) Fully appears you don't understand how your system works either? A scan tool can tell you the rear clutch pack duty cycle. But again, full time static split AWD isn't what this system is. It physically isn't feasible due to the overdrive gear. The rears must turn more than the front with the overdrive gear. You'll have irregular wear on the rear tires as they're skipping all the time and constant frying of the center clutch pack to convert the torque that isn't expelled from the system into heat. It's simple gearing.

6) The GR Yaris forum post simply doesn't account for the bare basics of how an overdrive system must operate to go 50 mph down a dead straight piece of road. When the rears must spin 1% faster than the front physically, how do you remove that torque from the system when all tires are at less than 5% maximum grip capacity? He has no solution for it and why it's such a limited understanding. At the limit when everything is slipping, sure you can drive the rears faster than the front as having some of the torque loss via the tire slip angles? Sure, it's how you get the rear to step out in a RWD car normally. But the understanding just doesn't work for 90% of the driving people do everyday as the car simply isn't crushing itself anytime it's on the road.
 

·
Registered
Joined
·
45 Posts
1) Your GR Yaris isn't permanent AWD. In fact it has a mode programmed into the computer to go into 2WD mode when the rear clutchpack temps rise at the track. It's inherent to any clutch based system as they're not physically connected when the clutch plate isn't squeezed. In a center differential system, the rear drive is permanently attached.

2) Not sure why it's so difficult to understand the difference between static split AWD and full time AWD. No one has said it's not full time AWD. Just doesn't bias anywhere near 40% to the rear all the time. If it did, the system would be trying to crush the car all the time and destroying the rear tires all the time due to the overdrive gear trying to spin the rear tires faster than the front. With any torque that can't be dissipated through the tires due to the tire grip must be converted to heat in the clutch pack which will fry it with at a minimum of 40% of all power always going to the rear in a static split.

3) Every AWD system available with an overdrive gear constantly adjusts the power going around the system. Be it GKN Twinsters or Type SH-AWD the rear only receives full squeeze down on the clutch pack after the front sensors have detected slip.Type-SH AWD specifically states cruising defaults to 95/5 split for not only gas mileage (static split AWD has terrible gas mileage as shown by Subaru) but for the service life of the rear clutchpack.

4) The Toyota supported Rally car isn't the same engine or drivetrain as your GR Yaris. Don't use it as a terrible comparison point of "it can't do ____ if it reverts to FWD" BTW the Evo reverts to FWD during mid turn as the rears travel a shorter circle in any given turn and why the Subaru WRX always understeers.

5) Fully appears you don't understand how your system works either? A scan tool can tell you the rear clutch pack duty cycle. But again, full time static split AWD isn't what this system is. It physically isn't feasible due to the overdrive gear. The rears must turn more than the front with the overdrive gear. You'll have irregular wear on the rear tires as they're skipping all the time and constant frying of the center clutch pack to convert the torque that isn't expelled from the system into heat. It's simple gearing.

6) The GR Yaris forum post simply doesn't account for the bare basics of how an overdrive system must operate to go 50 mph down a dead straight piece of road. When the rears must spin 1% faster than the front physically, how do you remove that torque from the system when all tires are at less than 5% maximum grip capacity? He has no solution for it and why it's such a limited understanding. At the limit when everything is slipping, sure you can drive the rears faster than the front as having some of the torque loss via the tire slip angles? Sure, it's how you get the rear to step out in a RWD car normally. But the understanding just doesn't work for 90% of the driving people do everyday as the car simply isn't crushing itself anytime it's on the road.
I

Toyota's own words:

"Every aspect of the car has a performance focus: an all-new platform and engine, new suspension, lightweight construction, aerodynamic styling and a new GR-FOUR permanent all-wheel-drive (AWD) system.
With high power and low weight, it has all the credentials for competition success, and for delivering exhilarating performance as a super-hot hatch for the road.".

Maybe you should take them to court for lying...
 

·
Registered
Joined
·
55 Posts
I

Toyota's own words:

"Every aspect of the car has a performance focus: an all-new platform and engine, new suspension, lightweight construction, aerodynamic styling and a new GR-FOUR permanent all-wheel-drive (AWD) system.
With high power and low weight, it has all the credentials for competition success, and for delivering exhilarating performance as a super-hot hatch for the road.".

Maybe you should take them to court for lying...
:rolleyes: Tell that to every GR Yaris owner whose AWD system shut off... It's not permanently attached, it's literally a clutchpack designed to vary engagement. In normal operation modes, sure, you can call it 'permanent' as it should be engaged to some degree but permanence has a different meaning to me. But I see you fall for marketing speak every single time so nothing technical will actually get through.
 

·
Registered
Joined
·
45 Posts
:rolleyes: Tell that to every GR Yaris owner whose AWD system shut off... It's not permanently attached, it's literally a clutchpack designed to vary engagement. In normal operation modes, sure, you can call it 'permanent' as it should be engaged to some degree but permanence has a different meaning to me. But I see you fall for marketing speak every single time so nothing technical will actually get through.
Do you own a Golf R by any chance? I've never seen anybody try to discredit a car's permanent AWD system as much as this, with as much passion...
 

·
Registered
Joined
·
55 Posts
Do you own a Golf R by any chance? I've never seen anybody try to discredit a car's permanent AWD system as much as this, with as much passion...
How defensive do you need to get over a technical issue? Does resorting to personal attacks make you think those will change the underlying mechanical system? :eek: You are a marketer's dream though. Believe everything they say, ignore understanding any of it, because - magic. Funny you're making this about Haldex/Golf R when I've never praised the system once but shows to how complete of an understanding you have before resorting to attacking.

You can read all you like about the base system the GR-Four is designed from here:

Watch the Hagerty video posted on page 3 if you want some semblance of understanding. Just comical this is what you joined the forum seemingly for by your posts.
 

·
Registered
Joined
·
63 Posts
I

Toyota's own words:

"Every aspect of the car has a performance focus: an all-new platform and engine, new suspension, lightweight construction, aerodynamic styling and a new GR-FOUR permanent all-wheel-drive (AWD) system.
With high power and low weight, it has all the credentials for competition success, and for delivering exhilarating performance as a super-hot hatch for the road.".

Maybe you should take them to court for lying...
This is a technicality, anyways. 95/5 is technically permanent AWD. The clutch just disengages when overheating. Under typical usage it is permanent, just not static. Permanent until overheat is the caveat, and definitely not static.

So its 95/5 or whatever it officially is, and then 50/50 when it wants (mid corner, accel, you name it) but it wont be static 50/50 when you’re on the highway going 75 for three hours.
 

·
Registered
Joined
·
45 Posts
How defensive do you need to get over a technical issue? Does resorting to personal attacks make you think those will change the underlying mechanical system? :eek: You are a marketer's dream though. Believe everything they say, ignore understanding any of it, because - magic. Funny you're making this about Haldex/Golf R when I've never praised the system once but shows to how complete of an understanding you have before resorting to attacking.

You can read all you like about the base system the GR-Four is designed from here:

Watch the Hagerty video posted on page 3 if you want some semblance of understanding. Just comical this is what you joined the forum seemingly for by your posts.
Could you please explain to me how I have personally attacked you?

I can't see anything in my wording to you that is a personal attack?
 

·
Registered
Joined
·
63 Posts
Honestly this is great info that @MCG1983 is convinced its always 60/40, 50/50, or 30/70. I was wondering how obvious the torque split transition would be. It means the system is well calibrated to not be obvious.
 

·
Super Moderator
Joined
·
1,274 Posts
How defensive do you need to get over a technical issue? Does resorting to personal attacks make you think those will change the underlying mechanical system? :eek: You are a marketer's dream though. Believe everything they say, ignore understanding any of it, because - magic. Funny you're making this about Haldex/Golf R when I've never praised the system once but shows to how complete of an understanding you have before resorting to attacking.

You can read all you like about the base system the GR-Four is designed from here:

Watch the Hagerty video posted on page 3 if you want some semblance of understanding. Just comical this is what you joined the forum seemingly for by your posts.
I get what you’re saying, but he wasn’t insulting/attacking you or anybody.
 

·
Registered
Joined
·
55 Posts
Could you please explain to me how I have personally attacked you?

I can't see anything in my wording to you that is a personal attack?
I get what you’re saying, but he wasn’t insulting/attacking you or anybody.
I cut him off early as there's only one way this goes. As he's offering nothing on the technical side of understanding as now he's trying to equate one's personal cars as a basis for discrediting how an AWD system works. This is only going to downward spiral now that the subject of his posts is not about the AWD system, but me. His posts have nothing to do with the GR Corolla or the AWD system, it's now about what car I drive and being consistent about how the system works as a negative. If you need wait until it spirals into name calling and all that... sure if we need to wait that long.
 

·
Registered
Joined
·
1 Posts
From the JTEKT technical documentation:

At the core of this torque management is JTEKTs electronically controlled AWD coupling, ITCC.*I
Capable of responding instantaneously, safe and controllable, ITCC offers continuous control of the
driving force delivered to the front and rear wheels, from 100:0 (front:rear) to 50:50 (front:rear).
When you are cruising down the highway with no turning or change in throttle I would be surprised if any power was going to the rear. Per the above quote the system can engage nearly instantly - faster than you can turn the wheel and notice a change, and faster than the engine can respond to any throttle changes. The system can engage faster than your senses, so for all intents and purposes it will always feel AWD when it needs to. Its a brilliant system.
 

·
Registered
Joined
·
63 Posts
From the JTEKT technical documentation:



When you are cruising down the highway with no turning or change in throttle I would be surprised if any power was going to the rear. Per the above quote the system can engage nearly instantly - faster than you can turn the wheel and notice a change, and faster than the engine can respond to any throttle changes. The system can engage faster than your senses, so for all intents and purposes it will always feel AWD when it needs to. Its a brilliant system.
Great info! The comment on that the AWD will react faster than the result of any input makes a lot of sense, and is what I was really looking to hear.
 

·
Registered
Joined
·
55 Posts
From the JTEKT technical documentation:



When you are cruising down the highway with no turning or change in throttle I would be surprised if any power was going to the rear. Per the above quote the system can engage nearly instantly - faster than you can turn the wheel and notice a change, and faster than the engine can respond to any throttle changes. The system can engage faster than your senses, so for all intents and purposes it will always feel AWD when it needs to. Its a brilliant system.
Keep in mind this is the 'base' system. There's known differences between the system listed on JTEKT's public website and the system installed on the GR Yaris and subsequently GR Corolla. In the overdrive gear and giving Toyota the benefit of the doubt when they state it's "permanent AWD." So natively I don't think the system goes 100:0 Front:Rear, but that's part of not knowing the specifics of the system and only the publicly available system from Toyota's manufacturing arm which we know isn't in the GR Yaris or GR Corolla in the exact form shown.

Great info! The comment on that the AWD will react faster than the result of any input makes a lot of sense, and is what I was really looking to hear.
The system runs at 120hz or faster... Meaning sample rate is 120x per second. The computer system's reaction time is going to be a lot quicker than human reaction time, however, it is all dependent upon what sensors need to trip before the system starts moving power around and how quickly the system can trigger the clutchpack to go from cruise to full clamp. You can basically see how quick this is on the roller tests posted earlier. Initiation of wheel movement starts at the front but in order to push off the roller it takes a few tenths of a second to send power rearward and get the car moving when the front wheels are on rollers shown in post #48.


So much of this has already been covered in the first 3 pages of this thread.
 

·
Registered
Joined
·
45 Posts
I cut him off early as there's only one way this goes. As he's offering nothing on the technical side of understanding as now he's trying to equate one's personal cars as a basis for discrediting how an AWD system works. This is only going to downward spiral now that the subject of his posts is not about the AWD system, but me. His posts have nothing to do with the GR Corolla or the AWD system, it's now about what car I drive and being consistent about how the system works as a negative. If you need wait until it spirals into name calling and all that... sure if we need to wait that long.
I'm a grown man. I'm not a child. I have no intentions of personally insulting anybody or name-calling on here and you have no evidence suggest such things. Unless of course you class somebody disagreeing with you as a personal insult? In which case, life is going to be extremely difficult for you going forward...

No disrespect, but you're talking about a car that you've never even driven yet.

I've been driving the GR-Four system for nearly a year now and I've not once had the system over-heat. I've not once had power distributed to the front wheels only.

You're basing all of your research from what you read on the internet with a couple of documented isolated cases where the aWD system has over-heated (extremely rare), with no personal experience.

If you want to believe that GR-Four is only temporary AWD, then suit yourself, but don't accuse me of future name calling via a none existent crystal ball to try and discredit me.

I'm sorry if asking you whether you owned a Golf hit a sore spot, that was not my intention.

I'm just here to chat about the GR brand as it's awesome.
 

·
Registered
Joined
·
55 Posts
I'm a grown man. I'm not a child. I have no intentions of personally insulting anybody or name-calling on here and you have no evidence suggest such things. Unless of course you class somebody disagreeing with you as a personal insult? In which case, life is going to be extremely difficult for you going forward...
Well, if we gotta go though the paces. Now even inferring how difficult my life will be for trying to stop this kind of silliness before it starts.

No disrespect, but you're talking about a car that you've never even driven yet.
One must operate a mechanical device to understand how a system works. Only by driving the specific car will I be able to unlock any knowledge of said car. Gotcha.

I've been driving the GR-Four system for nearly a year now and I've not once had the system over-heat. I've not once had power distributed to the front wheels only.
Great, you don't spend much time on the track then most likely. I've never said that in normal operation the car is a FWD car, simply that it's not a permanent attachment. As for thinking the car has NEVER, even for a millisecond went heavy FWD biased like 80%+? You don't know that. Only datalogging will give you that ability. Just by driving? Not a chance. This is the kind of data you can datalog and is the only way to know what exactly the system is doing.


You're basing all of your research from what you read on the internet with a couple of documented isolated cases where the 4WD system has over-heated (extremely rare), with no personal experience.
Yep, it's so rare there are aftermarket parts developed for the specific problem and numerous posts about it on the GR Yaris forums, youtube and reddit. Is it less than 10% of users? Yes. But less than 10% of users actually use their car on the track as well. No one is saying it's a common problem. Same to say the Civic Type-R doesn't heat soak for most users as well. But is it a problem at the track? Definitely. Just because your limited use case hasn't experienced it doesn't mean it's a non-issue but we see the narrow of a viewpoint you operate within - your experience only. But it was enough of an issue Toyota did something about it. They moved the exhaust pathing further away and added a vent to allow for more airflow. Again, this is just what it is. No idea why it's creating such an issue.

If you want to believe that GR-Four is only temporary 4WD, then suit yourself, but don't accuse me of future name calling via a none existent crystal ball to try and discredit me.
It literally attaches the driveshaft to the rear via a clutch pack. It functions just like the clutch you use to detach the engine from the transmission to shift the car. No amount of whatever you want to call this changes the functionality of what a clutch does. You've offered zero technical information as to how the system can work with an overdrive rear gear and have 40%+ of the torque always going to the rear without cooking the clutchpack - not even a theory. We know how the GKN Twinster works, we know how the Type-SH AWD system works, we get to see how the publicly available JTKET system this is likely based off of works. ALL the systems go heavy biased FWD to not burn up the clutchpack in order to cruise and improve gas mileage down a freeway. Honestly don't know why you're so threatened by this - it's just how these systems work and no amount of bickering changes their functionality. If you think they work differently, offer something tangible, it's not like most of these systems are new innovations. Even the roller tests show that the impulse of movement is the front wheels in sport mode. If it was 70% torque to the rear the initiation of movement would of been the entire car moving forward and not starting by spinning the front tires first. So you have technical information, comparable systems and practical testing... what else do you need? Let's hear your working theory.

I'm sorry if asking you whether you owned a Golf hit a sore spot, that was not my intention.
I don't own a Golf, never have owned a VW product, don't like the Haldex. It's simply the fact you're fishing to try and use that as leverage for your view now even trying to infer it's a sore spot... it's all early trolling stages.

I'm just here to chat about the GR brand as it's awesome.
This chatting about the GR brand being awesome consists of a single self serving sentence in your entire series of posts. Cool if that's your actual intent moving forward.
 

·
Registered
Joined
·
45 Posts
Well, if we gotta go though the paces. Now even inferring how difficult my life will be for trying to stop this kind of silliness before it starts.


One must operate a mechanical device to understand how a system works. Only by driving the specific car will I be able to unlock any knowledge of said car. Gotcha.


Great, you don't spend much time on the track then most likely. I've never said that in normal operation the car is a FWD car, simply that it's not a permanent attachment. As for thinking the car has NEVER, even for a millisecond went heavy FWD biased like 80%+? You don't know that. Only datalogging will give you that ability. Just by driving? Not a chance. This is the kind of data you can datalog and is the only way to know what exactly the system is doing.



Yep, it's so rare there are aftermarket parts developed for the specific problem and numerous posts about it on the GR Yaris forums, youtube and reddit. Is it less than 10% of users? Yes. But less than 10% of users actually use their car on the track as well. No one is saying it's a common problem. Same to say the Civic Type-R doesn't heat soak for most users as well. But is it a problem at the track? Definitely. Just because your limited use case hasn't experienced it doesn't mean it's a non-issue but we see the narrow of a viewpoint you operate within - your experience only. But it was enough of an issue Toyota did something about it. They moved the exhaust pathing further away and added a vent to allow for more airflow. Again, this is just what it is. No idea why it's creating such an issue.


It literally attaches the driveshaft to the rear via a clutch pack. It functions just like the clutch you use to detach the engine from the transmission to shift the car. No amount of whatever you want to call this changes the functionality of what a clutch does. You've offered zero technical information as to how the system can work with an overdrive rear gear and have 40%+ of the torque always going to the rear without cooking the clutchpack - not even a theory. We know how the GKN Twinster works, we know how the Type-SH AWD system works, we get to see how the publicly available JTKET system this is likely based off of works. ALL the systems go heavy biased FWD to not burn up the clutchpack in order to cruise and improve gas mileage down a freeway. Honestly don't know why you're so threatened by this - it's just how these systems work and no amount of bickering changes their functionality. If you think they work differently, offer something tangible, it's not like most of these systems are new innovations. Even the roller tests show that the impulse of movement is the front wheels in sport mode. If it was 70% torque to the rear the initiation of movement would of been the entire car moving forward and not starting by spinning the front tires first. So you have technical information, comparable systems and practical testing... what else do you need? Let's hear your working theory.


I don't own a Golf, never have owned a VW product, don't like the Haldex. It's simply the fact you're fishing to try and use that as leverage for your view now even trying to infer it's a sore spot... it's all early trolling stages.


This chatting about the GR brand being awesome consists of a single self serving sentence in your entire series of posts. Cool if that's your actual intent moving forward.
Ok, thank you. I respect your opinion on what constitutes as permanent AWD. Your opinion is just as valid as anybody else's, including mine.

I'm very excited for this car, because I think America is going to really enjoy it.

Enjoy your day.
 

·
Registered
Joined
·
55 Posts
Ok, thank you. I respect your opinion on what constitutes as permanent 4WD. Your opinion is just as valid as anybody else's, including mine.

I'm very excited for this car, because I think America is going to really enjoy it.

Enjoy your day.
Just like many things you've went into, it was covered earlier in this thread. One of those is what 4WD is, the GR Yaris or Corolla don't have the locking differential(s) that makes 4WD a thing. It's AWD. One thing that boggles my mind though your entire series there seems to be some confusion as to whether someone's opinion influences how a system works. It doesn't. It's simply how it works - physics, engineering, math and the computer programming within the system don't function any differently because your or my opinion agrees with it. But looks like we're not going to get the theory about how the GR Four system manages to have an overdrive rear gear and can transfer 50%+ of the torque to the rear wheels all the time and not fry or wear something from an owner who's unlocked the ability to understand such things? Oh well, our loss then. Have a good one.
 
121 - 140 of 158 Posts
Top