Limits of Sport Differential

[S4Flyer]

Reading some of the material Audi put out about the sports differential, they claim that in Comfort mode, vehicle safety and stability are the top considerations, and that in that mode, the SD will never allow the vehicle to enter an understeer scenario. They also allude to the fact that the ESP will never be needed in this scenario because the SD won't allow its necessity to arise.

Has anyone found this to be true? Spent any time on a skid pad, or gone into an overrun while tracking with SD in Comfort and ESP engaged?

Just curious what happens at the limit of tire traction and SD effectiveness. Does the car throttle/ABS back, or will it let you go wide on the turn?

[LittleDozer]

Reading some of the material Audi put out about the sports differential, they claim that in Comfort mode, vehicle safety and stability are the top considerations, and that in that mode, the SD will never allow the vehicle to enter an understeer scenario. They also allude to the fact that the ESP will never be needed in this scenario because the SD won't allow its necessity to arise.

Has anyone found this to be true? Spent any time on a skid pad, or gone into an overrun while tracking with SD in Comfort and ESP engaged?

Just curious what happens at the limit of tire traction and SD effectiveness. Does the car throttle/ABS back, or will it let you go wide on the turn?

Why would anyone want to oversteer while in comfort mode? It's comfort mode, no one should ever be in it on these cars IMO.

The SD definitely lets you oversteer. I let that rear kick out quite often.


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[The Fat Kid]

Reading some of the material Audi put out about the sports differential, they claim that in Comfort mode, vehicle safety and stability are the top considerations, and that in that mode, the SD will never allow the vehicle to enter an understeer scenario. They also allude to the fact that the ESP will never be needed in this scenario because the SD won't allow its necessity to arise.

Has anyone found this to be true? Spent any time on a skid pad, or gone into an overrun while tracking with SD in Comfort and ESP engaged?

Just curious what happens at the limit of tire traction and SD effectiveness. Does the car throttle/ABS back, or will it let you go wide on the turn?

Do you mean oversteer? Understeering is the more controllable scenario, which is why new tires (if only two are installed) are supposed to go on the rear tires.

I was never in comfort mode, so no help regardless.

[SonnyDeez]

Reading some of the material Audi put out about the sports differential, they claim that in Comfort mode, vehicle safety and stability are the top considerations, and that in that mode, the SD will never allow the vehicle to enter an understeer scenario. They also allude to the fact that the ESP will never be needed in this scenario because the SD won't allow its necessity to arise.

Has anyone found this to be true? Spent any time on a skid pad, or gone into an overrun while tracking with SD in Comfort and ESP engaged?

Just curious what happens at the limit of tire traction and SD effectiveness. Does the car throttle/ABS back, or will it let you go wide on the turn?

I've run the car on a skid pad with tc off and it definitely can understeer quite a bit, so I'm not sure what they're talking about

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[bmoreS4]

Not sure why this would ever happen.

Why would anyone be intentionally driving aggressively in comfort mode?




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[S4Flyer]

To clarify- I'm talking about driving with the SD in Comfort mode specifically, not the entire car in Comfort mode.

For the first year I owned the car, I drove in "Individual" with this setup:

Engine/DSG - Dynamic
Suspension - Auto
Steering - Dynamic
Sports Diff - Dynamic

A short time ago, I read in an AZ thread (which I can't find again) that an Audi rep was talking about the SD, and said that the SD is actually most aggressive in Comfort mode, not Dynamic mode, as you'd expect.

With the SD in Comfort mode, it works to its maximum ability to keep the car stable and inline on turns. Putting the SD into Dynamic mode prevents it from getting too involved, and lets the driver do things with the car on a track that you wouldn't necessarily desire on a public road. It took a while to start thinking this way, as every other drive select component seems more performance-oriented in Dynamic than Comfort.

I've driven for a couple of weeks with my Individual setup the same as before, but the SD set to Comfort. There are a few onramps I hit everyday, and I've noticed that I can't get the back to slide around at all. There's hardly any tire noise either.

At this point, I agree that the SD in Comfort mode is more active than when in Dynamic mode, though the car is a little less interesting to drive in turns.

So the question I'm asking (in the original post) is what happens when you ask the car to exceed it's grip in a turn with SD is in Comfort, and the ESP is on?

[administerturbo]

To clarify- I'm talking about driving with the SD in Comfort mode specifically, not the entire car in Comfort mode.

For the first year I owned the car, I drove in "Individual" with this setup:

Engine/DSG - Dynamic
Suspension - Auto
Steering - Dynamic
Sports Diff - Dynamic

A short time ago, I read in an AZ thread (which I can't find again) that an Audi rep was talking about the SD, and said that the SD is actually most aggressive in Comfort mode, not Dynamic mode, as you'd expect.

With the SD in Comfort mode, it works to its maximum ability to keep the car stable and inline on turns. Putting the SD into Dynamic mode prevents it from getting too involved, and lets the driver do things with the car on a track that you wouldn't necessarily desire on a public road. It took a while to start thinking this way, as every other drive select component seems more performance-oriented in Dynamic than Comfort.

I've driven for a couple of weeks with my Individual setup the same as before, but the SD set to Comfort. There are a few onramps I hit everyday, and I've noticed that I can't get the back to slide around at all. There's hardly any tire noise either.

At this point, I agree that the SD in Comfort mode is more active than when in Dynamic mode, though the car is a little less interesting to drive in turns.

So the question I'm asking (in the original post) is what happens when you ask the car to exceed it's grip in a turn with SD is in Comfort, and the ESP is on?

Fascinating stuff. I also wonder what Auto really is. I don't ever really feel it adapt. Feels like a genuine medium setting to me.

I also noticed that I got a little better MPG on a long trip while the throttle was in Comfort and SD was in auto. Not a surprise about the comfort throttle map, but SD was a surprise. Call me crazy...

[whiped]

So the question I'm asking (in the original post) is what happens when you ask the car to exceed it's grip in a turn with SD is in Comfort, and the ESP is on?

Mine was a jerky unpleasant surprise...

I almost always turn ESP off when I get in my car as I don't like it nannying me.

It had just rained so the roads were wet. Went to make a left turn out of my work parking lot and hit the gas to slide the back end a bit.

Lost traction for a second, then my wheels all locked for a second and almost pulsed until I had traction again.

It was super awkward and not predictable. ESP is always off now unless there is snow/ice on the ground.

Might have just been my car misbehaving but that is the only time it has ever happened and it sucked.

[bmoreS4]

I normally drive around with ESP in sport mode.

Lets me get loose but not crazy lol.


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[S4Flyer]

Fascinating stuff. I also wonder what Auto really is. I don't ever really feel it adapt. Feels like a genuine medium setting to me.

Haha... agree.

[S4Flyer]

Mine was a jerky unpleasant surprise...

I almost always turn ESP off when I get in my car as I don't like it nannying me.

It had just rained so the roads were wet. Went to make a left turn out of my work parking lot and hit the gas to slide the back end a bit.

Lost traction for a second, then my wheels all locked for a second and almost pulsed until I had traction again.

It was super awkward and not predictable. ESP is always off now unless there is snow/ice on the ground.

Might have just been my car misbehaving but that is the only time it has ever happened and it sucked.

Interesting. I had a similar experience on a wet on-ramp when the factory conti's were due for replacement. Def not a comfortable feeling.

I normally drive around with ESP in sport mode.

Lets me get loose but not crazy lol.


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Cool. I'll have to give that a whirl.

[brianc21]

To clarify- I'm talking about driving with the SD in Comfort mode specifically, not the entire car in Comfort mode.

For the first year I owned the car, I drove in "Individual" with this setup:

Engine/DSG - Dynamic
Suspension - Auto
Steering - Dynamic
Sports Diff - Dynamic

A short time ago, I read in an AZ thread (which I can't find again) that an Audi rep was talking about the SD, and said that the SD is actually most aggressive in Comfort mode, not Dynamic mode, as you'd expect.

With the SD in Comfort mode, it works to its maximum ability to keep the car stable and inline on turns. Putting the SD into Dynamic mode prevents it from getting too involved, and lets the driver do things with the car on a track that you wouldn't necessarily desire on a public road. It took a while to start thinking this way, as every other drive select component seems more performance-oriented in Dynamic than Comfort.

I've driven for a couple of weeks with my Individual setup the same as before, but the SD set to Comfort. There are a few onramps I hit everyday, and I've noticed that I can't get the back to slide around at all. There's hardly any tire noise either.

At this point, I agree that the SD in Comfort mode is more active than when in Dynamic mode, though the car is a little less interesting to drive in turns.

So the question I'm asking (in the original post) is what happens when you ask the car to exceed it's grip in a turn with SD is in Comfort, and the ESP is on?

Isn't this the exact opposite of how the sport diff actually works??

If it's in dynamic your going to get more action from the diff creating more power to the rear. In comfort there's less use of the diff creating less power to the rear....

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[rtmeikle]

Isn't this the exact opposite of how the sport diff actually works??

If it's in dynamic your going to get more action from the diff creating more power to the rear. In comfort there's less use of the diff creating less power to the rear....

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Close. If the sport diff is in dynamic, it's most active, and it pushes more power to the outside rear wheel in a turn. This serves to rotate the rear of the car better, eliminating under-steer and creating some over-steer.

Think of how a tank turns. The outside track spins faster than the inside track, turning the tank.

I do think the OP has it exactly backwards though. The diff is most active in the Dynamic mode, giving the car an almost RWD feel when accelerating through corners. Perhaps the car is more stable in comfort or automatic mode; I'm not sure. But the car is definitely more fun to drive with the diff in dynamic mode. It's a very noticeable effect.

[brianc21]

Close. If the sport diff is in dynamic, it's most active, and it pushes more power to the outside rear wheel in a turn. This serves to rotate the rear of the car better, eliminating under-steer and creating some over-steer.

Think of how a tank turns. The outside track spins faster than the inside track, turning the tank.

I do think the OP has it exactly backwards though. The diff is most active in the Dynamic mode, giving the car an almost RWD feel when accelerating through corners. Perhaps the car is more stable in comfort or automatic mode; I'm not sure. But the car is definitely more fun to drive with the diff in dynamic mode. It's a very noticeable effect.

Right. Just more detailed then I cared to get. He said it was most active in comfort mode. Which is inaccurate.

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[skiptowncat]

In sport mode it lets me get the back end pretty far out, which it won't in comfort...which one is the fastest way around a corner though?

[rtmeikle]

Right. Just more detailed then I cared to get. He said it was most active in comfort mode. Which is inaccurate.

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Yep. Only difference from what you said is that you suggested it put more power to the rear. It actually modulates power from side to side, not front to rear.

[S4Flyer]

Right. Just more detailed then I cared to get. He said it was most active in comfort mode. Which is inaccurate.

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I think we are saying the same thing, but differently. When the SD is "most active" (in Dynamic), it uses its full torque vectoring ability, and will let you get some oversteer into the mix by really sending power to the outside wheel. When in Comfort, its goal is to provide the safest and most stable turning. So it more actively interferes with aggressive driving habits, reducing the fun/danger.

In sport mode it lets me get the back end pretty far out, which it won't in comfort...which one is the fastest way around a corner though?

Exactly. Which is why when in Comfort, the SD interferes most with your "fun". Maybe it's not vectoring to its greatest ability, but it's definitely doing everything it can to keep the car stable and inline while turning.

So my questions stands: What happens when you push the car to its limit when your SD and ESP settings dictate that it be on its best behavior? Does it pull throttle? Activate ABS?

[skiptowncat]

The previous S4 was labelled as dull because of its neutral balance. I think with that in mind, Audi decided to make it more "fun" by inducing oversteer. It sometimes feels a bit too loose and carefree in sport, especially when you plant the throttle mid corner.

[darkstarghost]

I only use comfort when in traffic to lessen the throttle response interested to give you setup a try hmmm. and i normally run everything dynamic and ESP off.

[SwankP3RF3ct10n]

So my questions stands: What happens when you push the car to its limit when your SD and ESP settings dictate that it be on its best behavior? Does it pull throttle? Activate ABS?

ESP/TCS behaves the same way on the car whether you have an SD or not. It'll limit power by taking throttle control from you or it'll independently brake each corner of the car in order to regain it's composure. SD is there to help rotate the car or not. If you have your SD in Comfort, you're basically driving around with the car behaving very close to that of an S4 without SD (not really, but for the sake of the discussion, let's say this is the simplest way to explain how it'll feel). With the SD in Auto, it'll remain on the Comfort side of the scale, but it'll flip to the Dynamic side if it seems enough throttle angle and abruptness from the driver input. With it in Dynamic, it'll always be trying to help rotate the car. This is why if you have the SD is Comfort or Auto, if you're coming into a corner and braking hard, you won't feel the back end get light as if to try to rotate you when you actually start turning and applying throttle, you'll get a feeling like the car is staying straight or pushing a bit. In those two settings, the SD requires that you tell it your intention to want it to start rotating you by giving it ample throttle, then it'll kick to Dynamic and you'll feel it. With the SD in Dynamic, in the same scenario, as you're coming to the point where you want to turn and you're kinda trail braking or braking hard and then lifting, you will feel the back end feel a little lighter or looser (depending on how the driver describes that feeling) and when you turn the wheel and get off the brake and shift power, the back end will feel like it's more eager to snap around on you. With all this said, I feel that if you want the car to be most predictable and still be able to quickly dictate better turn or action from it's body, keep the SD in Auto. This is the reason why I ride around with Engine/Trans in Comfort and SD in Auto. With this combo, I can still get come slight oversteer out of it if I lay into the throttle if need be, but I don't have to worry about it looking too crazy should I want to whip around a corner quick and not make it look like I'm a hooligan with my ass hanging out too much. For the times I need Dynamic all around, it's a single button click in front of the shifter from Individual to Dynamic. BTW, steering for me is always in Dynamic.. Auto or Comfort is way too easy and loose and just lends itself badly to when you need to do steering corrections, but that's just my opinion.

[skiptowncat]

+1 for steering always in dynamic, feels like you're steering a canal barge otherwise

[SwankP3RF3ct10n]

+1 for steering always in dynamic, feels like you're steering a canal barge otherwise

Yep...

[absolutarin]

My idea is, rather was, that the Sport Diff is the most aggressive/responsive in the Dynamic Mode. I currently have everything set to Dynamic except for the throttle (I don't like the harsh downshifts ). A while ago I read that setting the ESP on Sport Mode also increased the "fun factor" in driving so I followed suit and set my ESP to Sport Mode every time I drive.

On my way to the office I have two consecutive road bends/turns (approx. 60 degrees and 30 deg respectively). One sunny day I felt too excited and wanted to give the Sport Diff a try so I went in at ~58-60 mph. Although I moved a bit inside on the seat, the car seemed to hold it very vERY well. BUT I did feel that I hit the limit with my existing ContiSportContact tires and my Adaptive Suspension set to Dynamic.
I am almost 100% sure that my car would have handled the turn way better if only it had F/R sway bars and the AK brace. Well, and obviously, coilovers too!

Now that you mention the SD works best/active on Comfort Mode, I will give it a try tomorrow and let you know if I had to call my insurance...

[SportVier]

So my questions stands: What happens when you push the car to its limit when your SD and ESP settings dictate that it be on its best behavior? Does it pull throttle? Activate ABS?

Both and more. In full "Comfort" mode, ESP will reduce power and apply brakes individually at each wheel earlier (versus Dynamic) as it detects slip. The SD will be less aggressive in shifting torque to the outside rear wheel when cornering, and will reduce torque to the outside wheel earlier.

[S4Flyer]

Thanks to all for the input. Interesting conversation.

Would love to find an autocross course to test all this out.

[whiped]

Thanks to all for the input. Interesting conversation.

Would love to find an autocross course to test all this out.

There are lots of empty parking lots around...

[S4Flyer]

There are lots of empty parking lots around...

Yeah, and it's super easy to measure performance of identical turns in an empty unmarked parking lot.