Intrusive DSC

[deeldoo]

What does it mean when people say that the F8X DSC is so intrusive that it hinders the diff from allowing the car to be agile/handle well.

How does this work?

What differences can i see driving with dsc on vs dsc fully off at 5/10.

Are the differences only apparent when you are full sending it?

[maddmatth]

It's just restricting you from doing anything that would result in wheelspin or slides.

The instant there will be any wheelspin it cuts power. If you're accelerating hard in a sharp bend it's restricting power so you can't kick the back end out.

But in the process it can often restrict power more than necessary.

Try MDM mode for a taste as that allows a bit of slip before intervening, but make sure you have a little room for error (IE, not a narrow street, no cars in the oncoming lane, just to be safe). Best if you have the software up to date as the MDM and diff behaviour is improved in the latest software.

[CanAutM3]

At 5/10th, you won't feel any intrusion. It is more when you get over ~8/10th that it becomes overly intrusive.

[IVM3]

As an easy test with warm summer tires on, try flooring it in first gear and shift into second with DSC on. You'll feel it cut power as it shifts into second. If you do this again with DSC off, you may get some tire spin but it won't cut any power.

[deeldoo]

Originally Posted by IVM3

As an easy test with warm summer tires on, try flooring it in first gear and shift into second with DSC on. You'll feel it cut power as it shifts into second. If you do this again with DSC off, you may get some tire spin but it won't cut any power.

No i get that as i primarily drive with DSC fully off, i am talking about cornering ability, is there a major difference in how the diff behaves in the 2 modes?

Does the car rotate much easier with DSC off?

[IVM3]

Originally Posted by deeldoo

No i get that as i primarily drive with DSC fully off, i am talking about cornering ability, is there a major difference in how the diff behaves in the 2 modes?

Does the car rotate much easier with DSC off?

Yes you will oversteer and spin the car easily if you go full throttle mid turn with DSC off. I wouldn't try it on the street.

[bsmf8x]

Originally Posted by deeldoo

No i get that as i primarily drive with DSC fully off, i am talking about cornering ability, is there a major difference in how the diff behaves in the 2 modes?

Does the car rotate much easier with DSC off?

Day and night difference

If you can lose control around a corner in US MDM (dry and decent tires) you're either drunk driving or on crack. You can slide for like a split second max

Meanwhile dsc off feels dangerous af to me when you're cornering, I wouldn't ever give throttle cornering with it off unless I'm on a track

[deeldoo]

Originally Posted by murdrdf82

Day and night difference

If you can lose control around a corner in US MDM (dry and decent tires) you're either drunk driving or on crack. You can slide for like a split second max

Ya see this is what i mean, i typically drove the car with DSC off completely and noticed recently as the weather is cooling down in toronto that with MDM on i don't feel the back end is as agile.

The car does not want to turn at all, it almost understeers a bit, so this is a complete revelation to me.

I have yet to really throw it around with DSC on but even with MDM the car is having trouble actually turning in hard

[bsmf8x]

Originally Posted by deeldoo

Ya see this is what i mean, i typically drove the car with DSC off completely and noticed recently as the weather is cooling down in toronto that with MDM on i don't feel the back end is as agile.

The car does not want to turn at all, it almost understeers a bit, so this is a complete revelation to me.

I have yet to really throw it around with DSC on but even with MDM the car is having trouble actually turning in hard

Yeah MDM feels awd with rear bias to me , under steery but the back has slight rotation

[maddmatth]

Originally Posted by deeldoo

Ya see this is what i mean, i typically drove the car with DSC off completely and noticed recently as the weather is cooling down in toronto that with MDM on i don't feel the back end is as agile.

The car does not want to turn at all, it almost understeers a bit, so this is a complete revelation to me.

I have yet to really throw it around with DSC on but even with MDM the car is having trouble actually turning in hard

Code Euro MDM if you want more fun

Also get it updated to the latest version. Even Euro MDM was crap on the 2015 SW, but in the current version it lets you do some decent little drifts and power-slides.

[McBobby Jr]

Originally Posted by deeldoo

What does it mean when people say that the F8X DSC is so intrusive that it hinders the diff from allowing the car to be agile/handle well.

How does this work?

What differences can i see driving with dsc on vs dsc fully off at 5/10.

Are the differences only apparent when you are full sending it?

No traction control any day of the week, assuming you're in good conditions. MDM cuts power by quite a bit, and can feel strange when taking corners at high speeds and will feel wobbly. The chassis is phenomenal, but if you don't know what you're doing it'll step out on you easy. My M4 is tuned and spins through third but still is relatively controllable. To answer your question, it is very intrusive. It feels like a completely different car to me as mine is tuned and cuts power instantly. Just have fun behind the wheel and burn some tires.

[jmg]

Originally Posted by deeldoo

Ya see this is what i mean, i typically drove the car with DSC off completely and noticed recently as the weather is cooling down in toronto that with MDM on i don't feel the back end is as agile.

The car does not want to turn at all, it almost understeers a bit, so this is a complete revelation to me.

I have yet to really throw it around with DSC on but even with MDM the car is having trouble actually turning in hard

Turn in is a function of front end grip. DSC isn't going to cause too much understeer here. Sounds like your are just going too fast for the conditions and you don't have enough weight on the front for traction.

[deeldoo]

Originally Posted by jmg

Turn in is a function of front end grip. DSC isn't going to cause too much understeer here. Sounds like your are just going too fast for the conditions and you don't have enough weight on the front for traction.

It isn't really a matter of the front end not biting it is a matter really of the back end feeling like it can't swing and rotate around.

Does that make sense?

[jmg]

Originally Posted by deeldoo

It isn't really a matter of the front end not biting it is a matter really of the back end feeling like it can't swing and rotate around.

Does that make sense?

You can't rotate a car without front end grip. Imagine you are on ice and your front end is completely loose and steering inputs have no effect so the car continues to slip straight across the ice. How do you make the car rotate? Shift the weight to the front with slight brake application, then turn. Your rear end should now come out.

Is the DSC light flashing on turn in? Then DSC is intervening because is senses slip in your front tires. It doesn't want you to oversteer. In order for you to allow for rotation is to make sure you don't induce slip in the front wheels. Shift the weight to the front.

Is DSC not flashing on turn in? Then it's not DSC that's causing understeer. It's the driver.

DSC is a bit intrusive on the F80. The GTS and CS maps help a lot. MDM on my CS allows for some more rotation than my civic F80... but the advantage I feel is mid corner to exit. The car loves to rotate mid corner in MDM. That being said, I tend to be hard on brakes leading up to turn in to maximize front end grip since the front end is where all the steering is on corner entry.

I don't track with DSC on anymore, but when I did, I used it as a guide. If DSC is flashing on turn in and I was experiencing understeer, I did something wrong.

[CanAutM3]

Originally Posted by jmg

Turn in is a function of front end grip. DSC isn't going to cause too much understeer here. Sounds like your are just going too fast for the conditions and you don't have enough weight on the front for traction.

Originally Posted by jmg

You can't rotate a car without front end grip. Imagine you are on ice and your front end is completely loose and steering inputs have no effect so the car continues to slip straight across the ice. How do you make the car rotate? Shift the weight to the front with slight brake application, then turn. Your rear end should now come out.

DSC can in fact alleviate understeer by applying the rear inside brake, inducing a yaw moment in the direction of the turn.

Originally Posted by jmg

Is the DSC light flashing on turn in? Then DSC is intervening because is senses slip in your front tires. It doesn't want you to oversteer. In order for you to allow for rotation is to make sure you don't induce slip in the front wheels. Shift the weight to the front.

Is DSC not flashing on turn in? Then it's not DSC that's causing understeer. It's the driver.

DSC is a bit intrusive on the F80. The GTS and CS maps help a lot. MDM on my CS allows for some more rotation than my civic F80... but the advantage I feel is mid corner to exit. The car loves to rotate mid corner in MDM. That being said, I tend to be hard on brakes leading up to turn in to maximize front end grip since the front end is where all the steering is on corner entry.

I don't track with DSC on anymore, but when I did, I used it as a guide. If DSC is flashing on turn in and I was experiencing understeer, I did something wrong.

The DSC system can make quick interventions without flashing the light in the cluster. I have witnessed this on multiple occasions.

[deeldoo]

I primarily drive with DSC off and mid corner the car feels good, it likes rotating it likes turning in.

The few times i have tried it with MDM mid corner is where i keep having to turn the wheel in to make the car turn properly at the same speed.

Not sure how it behaves to be perfectly honest.

A lot of the time coming into corner i will trail brake which easily rotates the car but mid corner if i am into the throttle DSC off the car corners well, MDM on it struggles it constantly seems like i have to keep putting it into the corner.

[jmg]

Originally Posted by CanAutM3

DSC can in fact alleviate understeer by applying the rear inside brake, inducing a yaw moment in the direction of the turn.

Yes, but I don't think it will directly cause more understeer if you are already experiencing it.

The ice example was meant to show what needs to happen to get the car to rotate during loss of traction. DSC applying rear inside braking is accomplishing pretty much the same conditions as I presented, slight braking to shift weight to produce rotation except we can't apply brakes to only one side or one wheel. It's basically like putting an oar in the water.

Originally Posted by CanAutM3

The DSC system can make quick interventions without flashing the light in the cluster. I have witnessed this on multiple occasions.

Interesting, I've never seen it, but then again, I just figured it blinked so quickly that I just didn't notice it on the cluster.

Either way, I think the logic still stands. If the DSC is flashing, then DSC is definitely intervening

If it's NOT flashing and the driver is experiencing understeer... it's still driver error!

[CanAutM3]

Originally Posted by jmg

Yes, but I don't think it will directly cause more understeer if you are already experiencing it.

The ice example was meant to show what needs to happen to get the car to rotate during loss of traction. DSC applying rear inside braking is accomplishing pretty much the same conditions as I presented, slight braking to shift weight to produce rotation except we can't apply brakes to only one side or one wheel. It's basically like putting an oar in the water.



Interesting, I've never seen it, but then again, I just figured it blinked so quickly that I just didn't notice it on the cluster.

Either way, I think the logic still stands. If the DSC is flashing, then DSC is definitely intervening

If it's NOT flashing and the driver is experiencing understeer... it's still driver error!

I meant that DSC has the ability to reduce understeer when it detects it and that you can in fact pivot the car without increasing front grip. It is not about "shifting the weight", it is really about inducing more yaw, ie pivoting the car, by applying the brakes to only one side. Brake torque vectoring in other words.

[jmg]

Originally Posted by deeldoo

I primarily drive with DSC off and mid corner the car feels good, it likes rotating it likes turning in.

The few times i have tried it with MDM mid corner is where i keep having to turn the wheel in to make the car turn properly at the same speed.

Not sure how it behaves to be perfectly honest.

A lot of the time coming into corner i will trail brake which easily rotates the car but mid corner if i am into the throttle DSC off the car corners well, MDM on it struggles it constantly seems like i have to keep putting it into the corner.

I see you have a 2016. I had a 2016 prior to my CS and yes, MDM and DCT are indeed more intrusive in that MY. People have coded their MDM with the GTS and CS map like I mentioned. I can get much more rotation in MDM in my CS than I did in my 2016 F80. Its allows for a little more fun on a public road without putting myself or others at additional risk. Personally, I don't run DCT off on public roads and MDM is more than enough freedom.

[deeldoo]

Originally Posted by jmg

I see you have a 2016. I had a 2016 prior to my CS and yes, MDM and DCT are indeed more intrusive in that MY. People have coded their MDM with the GTS and CS map like I mentioned. I can get much more rotation in MDM in my CS than I did in my 2016 F80. Its allows for a little more fun on a public road without putting myself or others at additional risk. Personally, I don't run DCT off on public roads and MDM is more than enough freedom.

I will be getting the steering and diff for CS coded on to my car as once again i don't want to risk driving continuously with DSC off but with DSC on i feel if i go too hot into a corner the car gets super unsettled and cuts power and just makes handling it an absolute mess.

I don't want to be relegated to fighting the car every time but i also don't want to be putting people or myself at risk, because at the end of the day no matter how confident one might feel, shit happens and that one time mdm is needed i want to have it.

[jmg]

Originally Posted by CanAutM3

I meant that DSC has the ability to reduce understeer when it detects it and that you can in fact pivot the car without increasing front grip.

Agreed, but in essence DSC is increasing front end grip (albeit biased towards the inside wheel). So whether or not it is directly induced by the driver or the DSC, that is what needs to happen.

Originally Posted by CanAutM3

It is not about "shifting the weight", it is really about inducing more yaw, ie pivoting the car, by applying the brakes to only one side. Brake torque vectoring in other words.

I understand completely and I don't mean to sound like I'm contradicting you at all, because I am not. In the post I was replying to the OP stated that his DSC is causing more understeer on turn in.

Technically, brake vectoring (ie brake based torque vectoring) is a function of weight distribution. Anytime the car is decelerating, the weight distribution shifts along the vector axis of force and velocity. When DSC is applying inside braking to allow the car to rotate, the force and velocity is increased upon the inside braking wheel. The weight distribution, therefore, shifts away from the outside corner and the rear (Newton's 3rd law)

In contrast, with DCT off, the driver can only apply the brakes to the wheels at once, so the vector of forces is distributed more evenly between left and right wheels (but not perfectly if the car was not in a state of lateral even g forces when the brakes were applied). In this way, the DCT can be more efficient, applying the braking on a single side which distributes the forces more towards the relevant wheel to induce yaw.

However, in both scenarios, the idea is almost the same: shift more weight towards the front where grip is need to allow the front wheels to induce rotation.

So, in applying this to the OP's problem: turn in understeer. If DSC is on, then it can apply inside brake to rotate the car. If DSC is off, then the driver needs to apply brakes to rotate the car.

In his last post, he also stated mid-corner understeer, which is totally different scenario for the DSC to deal with since the weight bias is now on the outside front wheels and the driver wants to apply throttle. DSC in this case, will cut the throttle to reduce mid-corner oversteer because it senses wheel slip in the rear, as opposed to applying brakes to reduce turn-in understeer where it senses slip in the front.

edited for clarity

[CanAutM3]

Originally Posted by jmg

Agreed, but in essence DSC is increasing front end grip (albeit biased towards the inside wheel). So whether or not it is directly induced by the driver or the DSC, that is what needs to happen.



I understand completely and I don't mean to sound like I'm contradicting you at all, because I am not. In the post I was replying to the OP stated that his DSC is causing more understeer on turn in.

Technically, brake vectoring (ie brake based torque vectoring) is a function of weight distribution. Anytime the car is decelerating, the weight distribution shifts along the vector axis of force and velocity. When DSC is applying inside braking to allow the car to rotate, the force and velocity is increased upon the inside braking wheel. The weight distribution, therefore, shifts away from the outside corner and the rear (Newton's 3rd law)

In contrast, with DCT off, the driver can only apply the brakes to the wheels at once, so the vector of forces is distributed more evenly between left and right wheels (but not perfectly if the car was not in a state of lateral even g forces when the brakes were applied). In this way, the DCT can be more efficient, applying the braking on a single side which distributes the forces more towards the relevant wheel to induce yaw.

However, in both scenarios, the idea is almost the same: shift more weight towards the front where grip is need to allow the front wheels to induce rotation.

So, in applying this to the OP's problem: turn in understeer. If DSC is on, then it can apply inside brake to rotate the car. If DSC is off, then the driver needs to apply brakes to rotate the car.

In his last post, he also stated mid-corner understeer, which is totally different scenario for the DSC to deal with since the weight bias is now on the outside front wheels and the driver wants to apply throttle. DSC in this case, will cut the throttle to reduce mid-corner oversteer because it senses wheel slip in the rear, as opposed to applying brakes to reduce turn-in understeer where it senses slip in the front.

edited for clarity

I believe you might be overthinking all this. DSC system operation is much simpler than this. The simple fact of braking a wheel on only one side of the car will induce a yaw moment on the car (think free body diagram). The DSC uses the tire on the axle that has most grip, rear axle to correct understeer and front axle for oversteer. To alleviate understeer it applies the rear inside brake to increase rotation. In a similar manner, in case of oversteer, it will apply the front outside brake to stop the rotation. Remember, not all oversteer is caused by too much throttle, you either have trailing throttle oversteer or power oversteer. Cutting power on trailing throttle oversteer will just make the situation worse. It is the application of the front outside brake that brings the car back. So the "stability" portion of a DSC system uses the brakes to point the car in the right direction. The "traction control" portion of the DSC system uses throttle to maintain forward traction.