[TurboGT]

To preface, this is a brake function discussion. Not another AWD discussion!

I've read the entirety of the "GR-FOUR AWD System Discussion" as well as the entirety of the GR Yaris AWD discussion linked on post 44 within.

In that Yaris discussion there was an article shared which mentioned something that's not entirely clear whether they were referring to the power application, or brake intervention

That being said, I'm looking for information on the brake vectoring of this vehicle. More specifically brake vectoring during acceleration.

What I'm trying to find out is if the Core model without the torsen diffs will have the "E-lsd" or brake-activated traction assistance.

Basically, I'll probably never track the car. I need the AWD because where I live the roads are always wet, then of course there's 5 months of winter. Acceleration into traffic is annoying most days. So if this system is in place, for my personal use, there's no reason for me to have torsen diffs.

If anyone has caught an explanation elsewhere or in one of these videos and can share, I'd appreciate it!

 

[Taroroot]

I think pretty much all modern cars in the US have traction control, including the GRC, which I think is pretty much doing what your're talking about. Applies brakes to a slipping wheel.

 

[Jeonsa]

To preface, this is a brake function discussion. Not another AWD discussion!

I've read the entirety of the "GR-FOUR AWD System Discussion" as well as the entirety of the GR Yaris AWD discussion linked on post 44 within.

In that Yaris discussion there was an article shared which mentioned something that's not entirely clear whether they were referring to the power application, or brake intervention


View attachment 2359


That being said, I'm looking for information on the brake vectoring of this vehicle. More specifically brake vectoring during acceleration.

What I'm trying to find out is if the Core model without the torsen diffs will have the "E-lsd" or brake-activated traction assistance.

Basically, I'll probably never track the car. I need the AWD because where I live the roads are always wet, then of course there's 5 months of winter. Acceleration into traffic is annoying most days. So if this system is in place, for my personal use, there's no reason for me to have torsen diffs.

If anyone has caught an explanation elsewhere or in one of these videos and can share, I'd appreciate it!

If you aren’t going to track it and it’s strictly a daily type thing, then getting the car without LSDs will save you cash.

 

[TurboGT]

If you aren’t going to track it and it’s strictly a daily type thing, then getting the car without LSDs will save you cash.

I'm the technical type. I'm specifically after a video or article covering the stability system. So I'd love to see some data points on the system and the amount of involvement it has in various drive modes. Etc.

I figure I'll have to wait until the car is released for this type of data (if this type of data is released at all) and maybe even early next year when a few guys have driven them through a winter to get actual real world feedback on the matter, and what their findings are.

But I'm patient, so hopefully I'll get the information I'm after in a few months.

 

[ryno9100]

I'm the technical type. I'm specifically after a video or article covering the stability system. So I'd love to see some data points on the system and the amount of involvement it has in various drive modes. Etc.

I figure I'll have to wait until the car is released for this type of data (if this type of data is released at all) and maybe even early next year when a few guys have driven them through a winter to get actual real world feedback on the matter, and what their findings are.

But I'm patient, so hopefully I'll get the information I'm after in a few months.

I tried doing some digging on the GR Yaris forums, but it almost seems like to be a member of the Yaris forums, you have to have LSDs. Lol

 

[Jeonsa]

I tried doing some digging on the GR Yaris forums, but it almost seems like to be a member of the Yaris forums, you have to have LSDs. Lol

There are a couple people that have no LSDs. Lol

 

[TurboGT]

@ryno9100 Thanks for putting some time into that! I didn't bother actually searching their forum beyond that topic because I would expect the Corolla to have a different stability control system than the Yaris, or at least different levels of involvement due to the size and weight differences between the two cars.

 

[Taroroot]

Theres youtube videos of the GR Yaris and other awd cars (focus i think) on rollers showing how it handles 0 traction in various combinations

 

[ryno9100]

Theres youtube videos of the GR Yaris and other awd cars (focus i think) on rollers showing how it handles 0 traction in various combinations

This is the one, I think.

 

[JimsGarageToys]

This is the one, I think.

The interesting thing from this is that the GRY has LSDs and the RS doesn't but they both seem to handle this test the same. I would have thought that the GRY would have still been able to get off the 3 rollers since it has the LSDs. Strange.

 

[ADent]

Well Torsen diffs are not true LSDs. The don't limit the slip (ie Limited Slip Differential).

They are 'torque sensing' and split the torque. So the wheel with grip can get say 4 times the torque of the slipping wheel. But if the slipping wheel is in the air or on ice or on good rollers - 4 x 0 = 0.

You can apply braking to raise the minimum torque and transfer some over.

So in a scenario with one wheel on each axle with no friction a GR-C or GR-Y could get stuck. In the video you see there is some friction in the system, so it gets off on all the two roller cases. Even with three wheels on rollers they get off most of the time - there just isn't much torque getting the that one wheel.

BTW clutch pack LSDs have issues too, just different ones.

 

[JimsGarageToys]

Well Torsen diffs are not true LSDs. The don't limit the slip (ie Limited Slip Differential).

They are 'torque sensing' and split the torque. So the wheel with grip can get say 4 times the torque of the slipping wheel. But if the slipping wheel is in the air or on ice or on good rollers - 4 x 0 = 0.

You can apply braking to raise the minimum torque and transfer some over.

So in a scenario with one wheel on each axle with no friction a GR-C or GR-Y could get stuck. In the video you see there is some friction in the system, so it gets off on all the two roller cases. Even with three wheels on rollers they get off most of the time - there just isn't much torque getting the that one wheel.

BTW clutch pack LSDs have issues too, just different ones.

So I would like to see how a GRC without the LSDs would handle the rollers.

 

[fredzy]

To preface, this is a brake function discussion. Not another AWD discussion!

I've read the entirety of the "GR-FOUR AWD System Discussion" as well as the entirety of the GR Yaris AWD discussion linked on post 44 within.

In that Yaris discussion there was an article shared which mentioned something that's not entirely clear whether they were referring to the power application, or brake intervention


View attachment 2359


That being said, I'm looking for information on the brake vectoring of this vehicle. More specifically brake vectoring during acceleration.

What I'm trying to find out is if the Core model without the torsen diffs will have the "E-lsd" or brake-activated traction assistance.

Basically, I'll probably never track the car. I need the AWD because where I live the roads are always wet, then of course there's 5 months of winter. Acceleration into traffic is annoying most days. So if this system is in place, for my personal use, there's no reason for me to have torsen diffs.

If anyone has caught an explanation elsewhere or in one of these videos and can share, I'd appreciate it!

I believe GRC does have brake-based torque vectoring, they just don't bang on about it like OEMs used to. The GRC owners manual talks a little bit about an "Expert Mode" TC/VSC setting:

Expert mode disables the TRAC and VSC systems but the engine and brakes may be controlled depending on the vehicle behavior.

Guarantee this is essentially the brakes tapping that inside wheel when it unloads and spins.

I dug this up because OF COURSE I end up being that guy (and there aren't many so far) who got a non-LSD allocation. LSD was not a must have for me because I will never track the car, but once their price was revealed I felt a little different about it. For $1200, why not? I'll keep this car long term so resale isn't a concern but I can't kid myself, it will always bug me that I didn't have the true GR-4 system as god intended it.

My experience with my WRX (open diffs F/R) was that there is no way in hell to get that car to show me it has open diffs outside of a track. Hitting the limits and exposing that weakness on public roads is simply reckless. Subaru touted the brake-based torque vectoring as a big deal with this car back in 2013/2014 when it came out.. it's just traction control lol. It was never clear whether tuning TC/DSC all completely OFF also stopped the car from using brakes to torque vector. I experimented with it but couldn't tell.

 

[ADent]

My experience with my WRX (open diffs F/R) was that there is no way in hell to get that car to show me it has open diffs outside of a track. Hitting the limits and exposing that weakness on public roads is simply reckless. Subaru touted the brake-based torque vectoring as a big deal with this car back in 2013/2014 when it came out.. it's just traction control lol. It was never clear whether tuning TC/DSC all completely OFF also stopped the car from using brakes to torque vector. I experimented with it but couldn't tell.

It doesn’t snow where you live, right?

Love the three wheel drive on the wife’s Outback in the snow.

But I agree the non PP GRC will drive perfectly fine in a sunbelt state.

PS You can’t turn off the VDC, but you can turn off the TC on our Subaru. The VDC is not super effective at times, esp if snow covered at low speeds.

 

[fredzy]

It doesn’t snow where you live, right?

Love the three wheel drive on the wife’s Outback in the snow.

But I agree the non PP GRC will drive perfectly fine in a sunbelt state.

PS You can’t turn off the VDC, but you can turn off the TC on our Subaru. The VDC is not super effective at times, esp if snow covered at low speeds.

Oh no, massive snow where I'm at. Snow tires + Subaru AWD with open diffs is plenty for day to day, never once left me wanting more in almost 9 years now. I've pulled multiple cars/trucks out of the ditch on our road when it was basically solid icy packed snow. I turn TC/DSC off when the wheels need to spin but I believe the torque vectoring still tries to keep wheel speeds matched up, which tends to split the torque when there's slip.

My bigger concern with open diffs and the GRC is cornering on pavement, any slip sucking fun from driving. Kneecapping the cars cornering attitude. I've seen some pretty damning GR Yaris comparisons but that was all-out track situation and the tires and suspension were 2 additional variables in those tests that were affecting behavior. It was the same concern I had with the WRX and it's probably as dumb of a thing to worry about now with GRC as it was for the WRX.

 

[TurboGT]

Well @fredzy, I'll definitely be looking forward to hearing your input and comparison to the Subaru in the snow after this winter. I appreciate you giving your 2 cents worth so far.

 

[ADent]

Yeah the track guys in Australia were much happier with the diffs in the GRY - less understeer at track speed IIRC.

I can tell the rear diff in the Outback works as I can get it sideways in the snow - fun for me, annoying for the wife. It’s a rocket ship in the snow on all seasons - even compared to my FWD Volvo with snows.

 

[TurboGT]

So to update this thread, another member here did some digging in Toyota's new model features and found that there is indeed some level of "E-LSD". Of course until we get these cars out in the snow, we won't know how effective it really is. However, I'm glad to hear that it's a thing.

I was perusing parts of the "New car features" section on TIS, just out of curiosity. ........... It's also interesting to note that even the ones without performance package still have a limited slip differential! It's just not designed to be quite as" affirmative action" as the torsen type limited slip diff, but it is a limited slip diff just the same.

I

 

[noogie]

The Performance Pack for 1,800 is a no brainer to me. It’s also going to be easier to sell since most people will want the LSDs.

 

[TurboGT]

The Performance Pack for 1,800 is a no brainer to me. It’s also going to be easier to sell since most people will want the LSDs.

Seeing as we don't have a choice on what we get, it isn't like some people will have the option to get one with the performance pack.

I do agree with you, but I'd like to keep discussion on topic just for the torque vectoring