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Dread man , truly dread
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Discussion Starter #1 (Edited)
Hello from a newcomer to the forum . I have a technical question I was wondering if anyone had the answer to .
It is regarding the brake steer and lack of a limited slip differential .
I understand how the bs can work on the way into a corner , braking the inside rear wheel a touch to assist turn in is very logical . What is less clear is on the way out when you are accelerating , my understanding is the process is used on the way out also ( as confirmed by mcl London just now ) its seems counterproductive to use brakes to aid acceleration but I can let that slide . The confusion is , now that you can turn traction control etc completely off , when you have turned everything off is the brake steer still doing the job of a limited slip differential on the way out or are you in effect now driving a car with an open differential ? Mcl london is looking into it for me , I thought it may be interesting to you all and someone may actually have the answer .
One more thing I presume there is a form of torque vectoring working in combination to the active roll bars and brake steer , can anyone confirm this ?
 

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Hello from a newcomer to the forum . I have a technical question I was wondering if anyone had the answer to .
It is regarding the brake steer and lack of a limited slip differential .
I understand how the bs can work on the way into a corner , braking the inside rear wheel a touch to assist turn in is very logical . What is less clear is on the way out when you are accelerating , my understanding is the process is used on the way out also ( as confirmed by mcl London just now ) its seems counterproductive to use brakes to aid acceleration but I can let that slide . The confusion is , now that you can turn traction control etc completely off , when you have turned everything off is the brake steer still doing the job of a limited slip differential on the way out or are you in effect now driving a car with an open differential ? Mcl london is looking into it for me , I thought it may be interesting to you all and someone may actually have the answer .
One more thing I presume there is a form of torque vectoring working in combination to the active roll bars and brake steer , can anyone confirm this ?
The Brake Steer system is essentially the torque vectoring system. Yes, it seems counter-intuitive to use the brakes while accelerating, but to have both wheels driving equally is not efficient as the car will push excessively to the outside of the track and therefore you will need to get off the throttle to get the car turned. Whether you use Brake Steer or a more conventional torque vectoring diff, the end result is the same - the outside wheel is allowed to drive while the inside wheel is limited in relation. That is my understanding, at least. I believe that Brake Steer remains functional with traction control disabled.
 

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Dread man , truly dread
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Discussion Starter #3 (Edited)
The Brake Steer system is essentially the torque vectoring system. Yes, it seems counter-intuitive to use the brakes while accelerating, but to have both wheels driving equally is not efficient as the car will push excessively to the outside of the track and therefore you will need to get off the throttle to get the car turned. Whether you use Brake Steer or a more conventional torque vectoring diff, the end result is the same - the outside wheel is allowed to drive while the inside wheel is limited in relation. That is my understanding, at least. I believe that Brake Steer remains functional with traction control disabled.
thanks for the answer .
I understand having both wheels driving equally is not ideal , that's what prompted my curiosity in the first place . Your answer leads me to ask if the bs is operational with driving aids turned off , are they truly off ? Or is there more to the traction / stability management than that ?Are you getting excessive brake pad wear ?
 

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thanks for the answer .
I understand having both wheels driving equally is not ideal , that's what prompted my curiosity in the first place . Your answer leads me to ask if the bs is operational with driving aids turned off , are they truly off ? Or is there more to the traction / stability management than that ?Are you getting excessive brake pad wear ?
Hmm, I can't find any specific reference to whether Brake Steer remains on with the rest of the systems off, so not sure about that. I would imagine that yes, Brake Steer does contribute to pad and rotor wear.
 

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The pad and rotor wear is very minimal,it might at first seem that the rear rotors are wearing at a similar rate as the fronts,but this is more to do with the airbrake allowing the use of the rear brakes more than on a normal braking system.Also the amount of times you use brakesteer is probably not more than 5% the total everyday usage and as far as im aware its more a feathering than full braking ,so its nothing to be worried about.
Im not totally sure the BS is switched off when you shut off the TC,but track mode is about right for most people,and driving with everything off with this power does seems a little rash,even though we have all tried it once:D
 

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Dread man , truly dread
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Discussion Starter #6
Hmm, I can't find any specific reference to whether Brake Steer remains on with the rest of the systems off, so not sure about that. I would imagine that yes, Brake Steer does contribute to pad and rotor wear.
Thanks mate
The pad and rotor wear is very minimal,it might at first seem that the rear rotors are wearing at a similar rate as the fronts,but this is more to do with the airbrake allowing the use of the rear brakes more than on a normal braking system.Also the amount of times you use brakesteer is probably not more than 5% the total everyday usage and as far as im aware its more a feathering than full braking ,so its nothing to be worried about.
Im not totally sure the BS is switched off when you shut off the TC,but track mode is about right for most people,and driving with everything off with this power does seems a little rash,even though we have all tried it once:D
Regarding the brake steer my interest is more for track driving rather than on the road .
The tc and sm questions are for when i want some hooliganism and want to play with the cars angle , hence my interest .
Thanks for the replies , I'm getting closer to wanting one of these even though it's nothing like the cars I usually go for .
 

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Thanks mate


Regarding the brake steer my interest is more for track driving rather than on the road .
The tc and sm questions are for when i want some hooliganism and want to play with the cars angle , hence my interest .
Thanks for the replies , I'm getting closer to wanting one of these even though it's nothing like the cars I usually go for .
I'm assuming you've watched Chris Harris' latest video. What I'm seeing from the hooliganism side of things is that the car will do sideways, but you can tell that it still wants to make forward progress at a massive rate. I noticed this from Goodwin's hooligan laps at Fontana, too. He is getting the car all out of shape, but the thing is still getting round the track faster than many cars would be while driving smoothly and quickly. Some of this is probably down to having to first overcome the car's inherent cornering grip, which is very high, so that the speeds are already elevated.
 

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Brake steer is used to control the open diff and reduce under-steer. It is indeed working with ESC off. If it wasnt then the inside wheel would spin on exit and you would have no acceleration out of the turns, no fun slides and too much understeer.

From the manual.

Brake-steer
Brake steer offers the benefits of a torque
vectoring differential, but is integrated into the
braking system reducing weight and providing
excellent speed of response.
If the system detects that the car is starting to
understeer through a corner, the inside rear
brake is gently applied. This helps to increase
the yaw rate of the car, making the car feel
more resistant to understeer. The lateral ‘g’
force is also increased giving better handling
characteristics.
If the driver uses too much throttle exiting a
corner, the inside rear wheel increases speed,
which without brake steer could cause the car
to become unstable. In this situation, brake
steer will again gently apply the brake on the
inside rear wheel, thereby restoring traction
and stability.
 

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Dread man , truly dread
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1,183 Posts
Discussion Starter #9 (Edited)
Brake steer is used to control the open diff and reduce under-steer. It is indeed working with ESC off. If it wasnt then the inside wheel would spin on exit and you would have no acceleration out of the turns, no fun slides and too much understeer.

From the manual.

Brake-steer
Brake steer offers the benefits of a torque
vectoring differential, but is integrated into the
braking system reducing weight and providing
excellent speed of response.
If the system detects that the car is starting to
understeer through a corner, the inside rear
brake is gently applied. This helps to increase
the yaw rate of the car, making the car feel
more resistant to understeer. The lateral ‘g’
force is also increased giving better handling
characteristics.
If the driver uses too much throttle exiting a
corner, the inside rear wheel increases speed,
which without brake steer could cause the car
to become unstable. In this situation, brake
steer will again gently apply the brake on the
inside rear wheel, thereby restoring traction
and stability.
Indeed mclaren london confirmed this today . Brake steer is on with stability and traction off .
 

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Dread man , truly dread
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1,183 Posts
Discussion Starter #10 (Edited)
I'm assuming you've watched Chris Harris' latest video. What I'm seeing from the hooliganism side of things is that the car will do sideways, but you can tell that it still wants to make forward progress at a massive rate. I noticed this from Goodwin's hooligan laps at Fontana, too. He is getting the car all out of shape, but the thing is still getting round the track faster than many cars would be while driving smoothly and quickly. Some of this is probably down to having to first overcome the car's inherent cornering grip, which is very high, so that the speeds are already elevated.
Yes the car does ( now ) do slides , I was interested in how exactly the systems work . Liking this car more and more now .
 

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Dread man , truly dread
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Discussion Starter #12
Have you driven it yet?
Yes but not hard enough to slide it around . Im thinking of buying one and mclaren are being fantastic , I'm getting closer all the time you saying yes .
I'm trying a car on track soon though I won't be using it much on track .
 

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Yes but not hard enough to slide it around . Im thinking of buying one and mclaren are being fantastic , I'm getting closer all the time you saying yes .
I'm trying a car on track soon though I won't be using it much on track .
I bet you bring it to Spa in May.....
 
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