Toyota GR Corolla Forum - Release Date, Specs, Pricing Discussion banner
101 - 120 of 158 Posts

·
Registered
Joined
·
55 Posts
Maybe I can rephrase. I'm just trying to understand if the GR-Four system will feel more like Haldex or a true full time AWD. Maybe the rear wheels will sense loss of grip fast enough that I couldn't even tell it was FWD based. I want a natural AWD feeling car on track, similar to how a subaru or evo might feel. I always strayed away from the Golf R, because of Haldex and the CTR because of FWD. The GRC is an incredible car, make no mistake, but I don't want a compromised AWD system.

As for pages 2-3 and throughout this thread, you've kept repeating your beliefs that the GR-four system is closely related to SH-AWD and certainly not a true full time AWD. Your reasoning makes complete sense to me, but I haven't read any other thread or article reach a similar conclusion. Even the in depth thread over at the GRY forum posted by OP doesn't mention it. Not to say you're wrong, but I usually like to hear from more than one forum member before considering something as factual.
Not sure what you mean by "compromised." But simply put, it's not a Haldex system. Haldex is compromised in a lot of ways in part of just the way you can't turn off the traction control system so it will always interfere. The electronic braking stability system will always kick in any why this system tends to eat rear brake pads. Compare this against the Ford Focus RS (GSK Twinster) or the VW 4Motion systems (new Mk8 Golf R and Audi RS3) if you want to remove the SH-AWD system. The Toyota JKEKT system just lacks the torque vectoring of those systems and instead relies on Torsen (if so equipped) LSD's to handle L/R grip which will retain a more 'natural' handling car vs the artificial torque vectoring overdrive which can feel electronic. It does incorporate the overdrive gear which Cammisa says is the best bandaid for the FWD based system to get the rear to rotate on power. But it is not the same as the Subaru (differential) or Mitsu (electronic clutch but no rear overdrive gear) or any differential or torque converter based system. Good on you for not blindly trusting the forum though, far too many times people just accept the easy answer like no one said the system isn't static, so it must be... Simply makes no sense to build it the way they did if that was the goal. Best resource all in once place I've found is this, but of course look for other answers. Unfortunately with any full time clutch based AWD system though, the clutchpack is an ingrained wear part and probably will need replacing more than a few times during the car's life BUT also note how many cars you see these systems on, so they can be reliable to a point.


However, in regards to driver feedback? Based upon the GR Yaris owners, it's a lot more of a driver's car than any Haldex. Put it on the same arena as the reviews for the TLX Type-S, Audi RS3/Mk8 Golf R, Ford Focus RS and now a bunch of others (but mainly used in more SUV applications). Just look up GKN Twinster as most of the designs are adopting their architecture. In general you'll see the feedback for their systems is very good with the main complaint being more about the torque vectoring aspect as a gimmick. But if you're looking for a RWD feeling car? None of these FWD based systems is it, it's the BMW xDrive and other RWD based systems that you're looking for.
 

·
Registered
2021 Civic Type R LE
Joined
·
15 Posts
I just realized almost all manufactures deleted the center diff probably to be more profitable and better MPG. It's annoying when it mostly 2wd cruising. and then kick on or off on icy roads and causing the tail to wag. I wish I kept my Lancer Evo for the snow. The AWD feels awesome and I dont' feel any issues. Just point and go.
 

·
Super Moderator
2011 FJ TT, 2001 IS300
Joined
·
1,544 Posts
You cannot use part time 4WD engaged (aka transfer case with no differential, front and rear driveshafts turn at same speed) on dry pavement . I mean you can, but it will result in extra strain on driveline components and tires…so you shouldn’t. When you force the front and rear to spin the same amount but they have less distance to travel, the extra “distance” has to go somewhere…on slippery surfaces the tires scrub it off. On dry surfaces you can experience tire hop or drivetrain bind.


View attachment 1925
Okay that was my misunderstanding. I thought you were saying part-time in general which had me confused. I know all about the binding on pavement😂. Thanks for the clarification!
 
  • Like
Reactions: kazoobaru

·
Super Moderator
2011 FJ TT, 2001 IS300
Joined
·
1,544 Posts
I guess it varies. IIRC the 4th gen 4Runner V6 you're supposed to be stopped. My old coworkers 2012(?) F150 you had to be stopped and it was sloooooow.
That's so odd. The FJ's, of course, have the same setup as the 4th gen V6 but all my warnings and manual say as long as you're under 50mph no matter if it's auto or manual
 

·
Registered
☆ 1991 Celica GTFour RC ☆ 2000 Grand Cherokee ☆
Joined
·
213 Posts
I might be misremembering then, it was 6 or 7 years ago now that I was looking into it. Is the change pretty instant or does it take a while?
 

·
Registered
2021 Civic Type R LE
Joined
·
15 Posts
So the GRC is a full time AWD car which is like a haldex but isn't since it always connected (full time)? Only con's would be overheating? If the awd is always engaged I'm still interested. I just hate the part time AWD system like the Haldex where you get the strange on and off awd feel when losing traction.
 

·
Registered
Joined
·
63 Posts
Not sure what you mean by "compromised." But simply put, it's not a Haldex system. Haldex is compromised in a lot of ways in part of just the way you can't turn off the traction control system so it will always interfere. The electronic braking stability system will always kick in any why this system tends to eat rear brake pads. Compare this against the Ford Focus RS (GSK Twinster) or the VW 4Motion systems (new Mk8 Golf R and Audi RS3) if you want to remove the SH-AWD system. The Toyota JKEKT system just lacks the torque vectoring of those systems and instead relies on Torsen (if so equipped) LSD's to handle L/R grip which will retain a more 'natural' handling car vs the artificial torque vectoring overdrive which can feel electronic. It does incorporate the overdrive gear which Cammisa says is the best bandaid for the FWD based system to get the rear to rotate on power. But it is not the same as the Subaru (differential) or Mitsu (electronic clutch but no rear overdrive gear) or any differential or torque converter based system. Good on you for not blindly trusting the forum though, far too many times people just accept the easy answer like no one said the system isn't static, so it must be... Simply makes no sense to build it the way they did if that was the goal. Best resource all in once place I've found is this, but of course look for other answers. Unfortunately with any full time clutch based AWD system though, the clutchpack is an ingrained wear part and probably will need replacing more than a few times during the car's life BUT also note how many cars you see these systems on, so they can be reliable to a point.


However, in regards to driver feedback? Based upon the GR Yaris owners, it's a lot more of a driver's car than any Haldex. Put it on the same arena as the reviews for the TLX Type-S, Audi RS3/Mk8 Golf R, Ford Focus RS and now a bunch of others (but mainly used in more SUV applications). Just look up GKN Twinster as most of the designs are adopting their architecture. In general you'll see the feedback for their systems is very good with the main complaint being more about the torque vectoring aspect as a gimmick. But if you're looking for a RWD feeling car? None of these FWD based systems is it, it's the BMW xDrive and other RWD based systems that you're looking for.
Appreciate the response and patience with my questions. Unless I am misunderstanding, all that I'm left wondering is how the car actually feel at the limit, or even at 7/10ths. I've also heard the praises of the GR Yaris, some of which is owed to the GR Four system. But, say, under a track session, does the driver feel 50/50 at all times, or will they feel some understeer for a fraction of a second and then the rear kick in to 50/50... That's where I see a subaru or evo system having a clear cut answer: It feels like a static torque split. Understeer or not, that can be dialed out with camber, aero, etc.

If the system truly feels like 50/50 or even 60/40 in normal mode, and not 95/5 until it finally decides to go to 50/50, then this system really is the answer. We'll be getting all the benefits of a predictable awd system and not sacrificing MPGs. GR Yaris has mpgs at 30+ if you're not beating the shit out of it, while a subaru might be lucky to see 24.

I'm skeptical of new electronic based innovations in enthusiast cars is all. Take a look at electric power steering, throttle by wire, rev hang, to name a few.
 

·
Registered
'13 FR-S, '09 Yaris 5 Dr, '88 Celica All-Trac, '87 FX16, '83 FJ40, '69 Datsun 510, Suzuki XL-7
Joined
·
364 Posts
All the reviewer rave about the GRY driving and handling, and watching the videos of it driven by competant drivers on the Nurburgring where it hangs with Porsche's in the curves seems to indicate the rear drive system works well and predictably.
 

·
Registered
☆ 1991 Celica GTFour RC ☆ 2000 Grand Cherokee ☆
Joined
·
213 Posts
But, say, under a track session, does the driver feel 50/50 at all times, or will they feel some understeer for a fraction of a second and then the rear kick in to 50/50...
Modern systems are incredibly responsive though, I highly doubt you'd ever be able to notice the delay if there even is one. Totally different system I know, but I set up lights to monitor the eLSDs in my 3rd gen Grand Cherokee and they were adjusting lock levels incredibly quickly, certainly far before I noticed anything, and that was just in a crappy old Jeep. A brand new sports car is going to be way beyond that.
 

·
Registered
Joined
·
55 Posts
Appreciate the response and patience with my questions. Unless I am misunderstanding, all that I'm left wondering is how the car actually feel at the limit, or even at 7/10ths. I've also heard the praises of the GR Yaris, some of which is owed to the GR Four system. But, say, under a track session, does the driver feel 50/50 at all times, or will they feel some understeer for a fraction of a second and then the rear kick in to 50/50... That's where I see a subaru or evo system having a clear cut answer: It feels like a static torque split. Understeer or not, that can be dialed out with camber, aero, etc.

If the system truly feels like 50/50 or even 60/40 in normal mode, and not 95/5 until it finally decides to go to 50/50, then this system really is the answer. We'll be getting all the benefits of a predictable awd system and not sacrificing MPGs. GR Yaris has mpgs at 30+ if you're not beating the shit out of it, while a subaru might be lucky to see 24.

I'm skeptical of new electronic based innovations in enthusiast cars is all. Take a look at electric power steering, throttle by wire, rev hang, to name a few.
Simply put, no. If you are looking for a static torque split between the F/R you can't have the overdrive gear connecting to the rear drivetrain. The Mitsubishi ACD system is a clutch based system which connects and disconnects the rear of the car depending on steering angle and other sensors but can be a generally 50/50 split because it doesn't have the overdrive gear in the rear. In general though because the Mitsubishi system has the ability to go basically entirely FWD mid turn it handles better than the full time differential based Subaru system which is prone to understeer and because of the design, to be fast the Subaru system has to understeer near the limit by the drivetrain design. Trying to make it more neutral to oversteer biased only makes you slower. I've mentioned some cars with similarly designed systems to the GR-Four system, go see if you can catch a drive in one of those as keyboard driving isn't going to do you much good if really don't understand the technical system under it - you'll just have to drive it.
 

·
Super Moderator
2011 FJ TT, 2001 IS300
Joined
·
1,544 Posts
All the reviewer rave about the GRY driving and handling, and watching the videos of it driven by competant drivers on the Nurburgring where it hangs with Porsche's in the curves seems to indicate the rear drive system works well and predictably.
That Porsche driver had no idea what he was doing 😂
 
  • Haha
Reactions: Jeonsa

·
Registered
Joined
·
45 Posts
Thanks for the link, if that's the system that's installed on the GR Yaris/Corolla then that's not a full time AWD system. Though that specific link (I didn't dive down JTEKT's product offerings) doesn't mention an overdrive version. You can see on Page 3 this specific system only becomes AWD when it detects slip.
It's 100% permanent AWD. This aint no Golf.
 

·
Registered
Joined
·
45 Posts
I agree the difference in speed between the front and rear wheels has to scrub some where…either into the clutches or off on the tires. So you’re saying the GR-FOUR system is not full time 4WD and is normally FWD …everything I’ve read and heard so far indicates different…I’ll be really disappointed if that’s the case

i also want to say that everyone loves saying “open differentials send all the power to the slipping wheel/path of least resistance “…this is incorrect. It transmits equal torque to both sides but allows for different speeds. It can only however transmit as much torque as the least resistive (least grip) side can handle
The GR-Four system is permanent AWD.

Ignore anybody that tells you otherwise, they are getting themselves confused.
 

·
Registered
Joined
·
45 Posts
Source???
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.
 

·
Registered
Joined
·
101 Posts
Discussion Starter · #120 ·
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)
 
101 - 120 of 158 Posts
Top