Could you live without the Adaptive Chassis Control?

[drkaos]

When VW released the rocco, 2 cars were tested on a track here in Norway. The 1,4 160hp(without acc/dcc) vs 200hp (with acc/dcc)

The 200hp was a bit faster overall, but totally nuked the 160hp version in the corners due to acc/dcc. I also noticed that fifth gear really enjoyed the acc/dcc, especially in the combination with dsg.
If you are to slam the car (using coilovers/gewinde), there's no point in acc/dcc (unless you want the steering and throttle response set-up). I ordered my car WITH this option, because I won't lower it anymore than 35mm or so with H&R or Eibach springs.
So far the combination of 35mm lowering and acc/dcc-option looks great for track and road-use.

[Andy-GTI]

Nice write up David, but you miss a few hings. . . .

You ignore the fact that you are not changing the spring rate, so the 'stiffness' of the suspension remains the same (as it is the springs that take the load, not thew dampers), all you are changing is the compression (and possibly the rebound - but i'm not 100% sure) damping rate

So in effect all you are incresing is the resitance to roll, not the actual amount the car will roll, given a long enough corner (to allow the dampers to move) the car will get to a point with the weight transfer onto the springs to the same point regardless if its in sport or comfort.

There also factors such as the camber, toe and castor change during steering and suspension movement that affect the contact patch of the tyre, which directly affect the grip available.

Basically there are a whole heap of factors involved, So blanketly saying that a softer suspension setup is beter is mis-information. IMO

If you find a setting on the scirocco that suits your dirving style then thats the best setup for you, someone else will want something different


Note: You also lower cars to get the roll centre closer to the centre of gravity, by reducing the distance you reduce the turning moment induced, that actually reduces the cars 'want' to roll. (lowering too much can actually go past the sweet point and make it worse)

[DavidH]

Well, i couldn't exactly write a whole book on vehicle dynamics, in a thread. The fact is i explained a fundamental, root part of it is that an excellent way to begin to understand what we observe when we make setup changes, in a concise way and i wrote it in my own words. There is no misinformation in that post. Confusing the matter with other variables at this stage doesn't alter this fundamental and important concept that must become second nature.

Saying that geometry changes with suspension movement (we all know that) doesn't change the way we need to understand load transfer across an axle and how it relates to roll stiffness, and how that affects grip. It lets us understand grip in a comprehendable way. It gives an explaination for the observations we see.

So of course what i wrote is incomplete, there's more to learn than that, but it's a very good introduction, and you can use that info alone to make affective adjustments to the handling balance of a car, by thinking in terms of relative roll stiffness. I even explained why we see this phenomenon, that it's due to a fundamental way that tyres behave, that there is this net loss as load is transfered, that's the way to think about it. Then a lot of things become less of a mystery, including when you begin think about roll centres.

Changing the damping does in fact change the extent to which the car rolls, in fact if you go out in the 'rocco with ACC you can demonstrate this for yourself. (the force required to overcome the damping and move the suspension further becomes limiting)

[wigit]

so the question is jphealy are your going to tike the box or not?

decisions, decisions

[DavidH]

I vote yes, come on man, it's a wicked toy, and gives you a choice of settings to suit your mood, road suface or whatever. It incerases the enjoyment of the car (atleast it does fror me) and that's the bottom line. Tick it i says!

[Andy-GTI]

Well, i couldn't exactly write a whole book on vehicle dynamics, in a thread. The fact is i explained a fundamental, root part of it is that an excellent way to begin to understand what we observe when we make setup changes, in a concise way and i wrote it in my own words. There is no misinformation in that post. Confusing the matter with other variables at this stage doesn't alter this fundamental and important concept that must become second nature.

Saying that geometry changes with suspension movement (we all know that) doesn't change the way we need to understand load transfer across an axle and how it relates to roll stiffness, and how that affects grip. It lets us understand grip in a comprehendable way. It gives an explaination for the observations we see.

So of course what i wrote is incomplete, there's more to learn than that, but it's a very good introduction, and you can use that info alone to make affective adjustments to the handling balance of a car, by thinking in terms of relative roll stiffness. I even explained why we see this phenomenon, that it's due to a fundamental way that tyres behave, that there is this net loss as load is transfered, that's the way to think about it. Then a lot of things become less of a mystery, including when you begin think about roll centres.

Changing the damping does in fact change the extent to which the car rolls, in fact if you go out in the 'rocco with ACC you can demonstrate this for yourself. (the force required to overcome the damping and move the suspension further becomes limiting)

By ingnoring the other contirbuting factors you CANNOT say that there is always a net loss in grip with stiffer suspension - that is simply not true. Certain setups may indeed be worse for stiffer suspension. Can you prove this is the case for the Scirocco? Have you got any evidence?

Also the only effect the dampers have on how far the car rolls is dependant on the duration of time the suspension sees the load - given sufficient time (depending on the load applied and damper rate) the dampers will move exactly the same distance beacuse it is the spring which compresses to balance the forces, the damper fluid does not take the load, it merely controls the rate at which the load is taken up by the spring.

[CTRnutter]

To cut a long story short and without going into the science behind grip! Ask yourself a very simple question, why have the VAG group gone to so much trouble and money to design and fit this sytem if it doesnt work?

I for one have noticed its advantages, I prefer flatter cornering and I find that softer suspension with more rebound can unsettle the car whereas a tighter setup allows me to enter and exit a bend at greater speed, body roll doesnt necessrily mean loss of traction, but the shift in weight will cause understeer to a degree, which unfortunately the Rocco suffers from.

Now the disadvantage of the sport setting is that the ride quality drops, not by a great deal but on a long journey it would become noticable, which is why its a great joy to be able to put it into comfort mode.

Without ACC you wont get the extreme of sport and the extreme of comfort, you'll have a half measure of both! Yes you can get aftermarket adjustable suspension, but I dont have to get out a spanner each time I want to set it up lol and yes you can get an aftermarket electronic solution albeit not available for the roc yet and it will cost more than 1k,

[DavidH]

Well, i couldn't exactly write a whole book on vehicle dynamics, in a thread. The fact is i explained a fundamental, root part of it is that an excellent way to begin to understand what we observe when we make setup changes, in a concise way and i wrote it in my own words. There is no misinformation in that post. Confusing the matter with other variables at this stage doesn't alter this fundamental and important concept that must become second nature.

Saying that geometry changes with suspension movement (we all know that) doesn't change the way we need to understand load transfer across an axle and how it relates to roll stiffness, and how that affects grip. It lets us understand grip in a comprehendable way. It gives an explaination for the observations we see.

So of course what i wrote is incomplete, there's more to learn than that, but it's a very good introduction, and you can use that info alone to make affective adjustments to the handling balance of a car, by thinking in terms of relative roll stiffness. I even explained why we see this phenomenon, that it's due to a fundamental way that tyres behave, that there is this net loss as load is transfered, that's the way to think about it. Then a lot of things become less of a mystery, including when you begin think about roll centres.

Changing the damping does in fact change the extent to which the car rolls, in fact if you go out in the 'rocco with ACC you can demonstrate this for yourself. (the force required to overcome the damping and move the suspension further becomes limiting)

By ingnoring the other contirbuting factors you CANNOT say that there is always a net loss in grip with stiffer suspension - that is simply not true. Certain setups may indeed be worse for stiffer suspension. Can you prove this is the case for the Scirocco? Have you got any evidence?

Also the only effect the dampers have on how far the car rolls is dependant on the duration of time the suspension sees the load - given sufficient time (depending on the load applied and damper rate) the dampers will move exactly the same distance beacuse it is the spring which compresses to balance the forces, the damper fluid does not take the load, it merely controls the rate at which the load is taken up by the spring.

I've already expalined it man. Just assume that geometry is constant for a minute in order to grasp the concept (we really need to understand this before anything else- or it's like trying to run before we can walk). I'm not going to reiterate a million times, go back and read it if you're interested in this stuff. What i'm not claiming is what it seems you're suggesting, that the 'rocco will always have more grip in the softer mode, you're right there are more factors, and we don't necessarily know without testing it (we can have a bloody good guess that it will though). Changing suspension geometry as the suspension cycles being one (although you claim this doesn't change with dampin i can assure you it does-like i said it becomes limiting, it doesn't only affect speed- even if like you say it doesn't limit roll in the end, it does for a long enough time to have an effect on grip,no? ) . The ride height is fixed so you can't reduce load transfer by lowering it, the only way to increase grip is to soften off the car to allow increased roll, therefore reducing load transfer and increasing grip as we have less net loss. ( this can indeed be achieved with damping). You're right that there are other factors (namely changing geometry affecting the contact patch) that may prevent this from coming to fruition, the the theory is sound and very important to understand, these are the fundamentals.

I tell you what we need man, something to measure roll. and a G-meter That might actually be a pretty cool experiment, don't ya think If you want to see it proven ,that would be a cool thing to do.

[CTRnutter]

Well, i couldn't exactly write a whole book on vehicle dynamics, in a thread. The fact is i explained a fundamental, root part of it is that an excellent way to begin to understand what we observe when we make setup changes, in a concise way and i wrote it in my own words. There is no misinformation in that post. Confusing the matter with other variables at this stage doesn't alter this fundamental and important concept that must become second nature.

Saying that geometry changes with suspension movement (we all know that) doesn't change the way we need to understand load transfer across an axle and how it relates to roll stiffness, and how that affects grip. It lets us understand grip in a comprehendable way. It gives an explaination for the observations we see.

So of course what i wrote is incomplete, there's more to learn than that, but it's a very good introduction, and you can use that info alone to make affective adjustments to the handling balance of a car, by thinking in terms of relative roll stiffness. I even explained why we see this phenomenon, that it's due to a fundamental way that tyres behave, that there is this net loss as load is transfered, that's the way to think about it. Then a lot of things become less of a mystery, including when you begin think about roll centres.

Changing the damping does in fact change the extent to which the car rolls, in fact if you go out in the 'rocco with ACC you can demonstrate this for yourself. (the force required to overcome the damping and move the suspension further becomes limiting)

By ingnoring the other contirbuting factors you CANNOT say that there is always a net loss in grip with stiffer suspension - that is simply not true. Certain setups may indeed be worse for stiffer suspension. Can you prove this is the case for the Scirocco? Have you got any evidence?

Also the only effect the dampers have on how far the car rolls is dependant on the duration of time the suspension sees the load - given sufficient time (depending on the load applied and damper rate) the dampers will move exactly the same distance beacuse it is the spring which compresses to balance the forces, the damper fluid does not take the load, it merely controls the rate at which the load is taken up by the spring.

I've already expalined it man. Just assume that geometry is constant for a minute in order to grasp the concept (we really need to understand this before anything else- or it's like trying to run before we can walk). I'm not going to reiterate a million times, go back and read it if you're interested in this stuff. What i'm not claiming is what it seems you're suggesting, that the 'rocco will always have more grip in the softer mode, you're right there are more factors, and we don't necessarily know without testing it (we can have a bloody good guess that it will though). Changing suspension geometry as the suspension cycles being one (although you claim this doesn't change with dampin i can assure you it does-like i said it becomes limiting, it doesn't only affect speed- even if like you say it doesn't limit roll in the end, it does for a long enough time to have an effect on grip,no? ) . The ride height is fixed so you can't reduce load transfer by lowering it, the only way to increase grip is to soften off the car to allow increased roll, therefore reducing load transfer and increasing grip as we have less net loss. ( this can indeed be achieved with damping). You're right that there are other factors (namely changing geometry affecting the contact patch) that may prevent this from coming to fruition, the the theory is sound and very important to understand, these are the fundamentals.

I tell you what we need man, something to measure roll. and a G-meter That might actually be a pretty cool experiment, don't ya think If you want to see it proven ,that would be a cool thing to do.

I'm game if you guys can get the meter, give me a fast bend and I'm there ha ha but I reckon we need a few consecutive bends, long sweepers, chicanes, on and off camber, to really prove that the ACC works

[krn1]

I'm sure I read in Performance VW that the ACC is actually continuously adjustable, that the 3 settings are just there for ease of use and a whole new area of suspension tuning by the likes of Revo etc could open up in the future

[DavidH]

I'm sure I read in Performance VW that the ACC is actually continuously adjustable, that the 3 settings are just there for ease of use and a whole new area of suspension tuning by the likes of Revo etc could open up in the future

Yeah, it's active, that's what's so cool about it. There's a couple of videos here that explain what it's doing http://www.volkswagen.com/vwcms/master_ ... n/dcc.html

The three different modes result in three different sets of output/control data, so while it's active you still have different damping rates in the different modes for the same input data. That wasn't the greatest explanation but just watch the videos.

[jphealy]

so the question is jphealy are your going to tike the box or not?

decisions, decisions

I certainly want to tick the box, but the question is - how much is a reasonable amount to spend on extras? It'll be the 1.4 160, which is €29k, and I want to add Interlagos wheels, Sport Pack (includes Catch-Up Alcantara/leather/cloth upholstery, metal pedals, tinted rear windows, mats, black roof lining, front fog lights), parking sensors, light pack (auto lights, coming home etc. and rain sensor) RCD510 with Dynaudio (RCD310 is standard), tyre monitor, multifunction steering wheel, and then maybe ACC. With all those options, it comes to about €35k. That's €6k on extras! Surely that's a bit mad??

By the way, €35k converts to £31,400. To get the same (or as near as possible - no Catch-Up, so swap for leather) in the UK costs about £22k. So I'm paying about £10k more for the same car here. It hurts when I put it like that. Just thought I'd let you Brits know how sweet you had it.

So anyway, I haven't figured out my budget yet, and it could be a while before I can afford it at all (as you can see - it ain't quite so cheap for us). But how mad should I be going on the extras???

Thanks for all the great help so far, btw.

[wigit]

jpheally i know you guys have some great roads over there to try it out, just had a danish supplier say the same thing about new car costs in denmark

[silver130]

I like it and use all the time but. Over £1000 option. Now i am not so sure i would tick the box..
On another related point. is it just me or does the exhaust note seem to make a bit more growl in sport mode ??

[drkaos]

That might be due to the changes in throttle-response.

[heavymetalmayhem]

so the question is jphealy are your going to tike the box or not?

decisions, decisions

I certainly want to tick the box, but the question is - how much is a reasonable amount to spend on extras? It'll be the 1.4 160, which is €29k, and I want to add Interlagos wheels, Sport Pack (includes Catch-Up Alcantara/leather/cloth upholstery, metal pedals, tinted rear windows, mats, black roof lining, front fog lights), parking sensors, light pack (auto lights, coming home etc. and rain sensor) RCD510 with Dynaudio (RCD310 is standard), tyre monitor, multifunction steering wheel, and then maybe ACC. With all those options, it comes to about €35k. That's €6k on extras! Surely that's a bit mad??

By the way, €35k converts to £31,400. To get the same (or as near as possible - no Catch-Up, so swap for leather) in the UK costs about £22k. So I'm paying about £10k more for the same car here. It hurts when I put it like that. Just thought I'd let you Brits know how sweet you had it.

.

I don't understand why you don't buy in the UK given the better spec and favourable exchange rate?

[heavymetalmayhem]

I was about to say the same it makes no difference to throttle well at least I didnt think it did!?

I thought sport sharpened the throttle response. I find that with DSG in sport mode it can be quite difficult to accelerate quickly and smoothly in the wet without wheel spin where as in comfort I find it easier to balance and prevent wheel spin. Also I find in-gear acceleration is sharper in sport mode and the DSG will change down where as in comfort it will hold a gear longer.

[jphealy]

so the question is jphealy are your going to tike the box or not?

decisions, decisions

I certainly want to tick the box, but the question is - how much is a reasonable amount to spend on extras? It'll be the 1.4 160, which is €29k, and I want to add Interlagos wheels, Sport Pack (includes Catch-Up Alcantara/leather/cloth upholstery, metal pedals, tinted rear windows, mats, black roof lining, front fog lights), parking sensors, light pack (auto lights, coming home etc. and rain sensor) RCD510 with Dynaudio (RCD310 is standard), tyre monitor, multifunction steering wheel, and then maybe ACC. With all those options, it comes to about €35k. That's €6k on extras! Surely that's a bit mad??

By the way, €35k converts to £31,400. To get the same (or as near as possible - no Catch-Up, so swap for leather) in the UK costs about £22k. So I'm paying about £10k more for the same car here. It hurts when I put it like that. Just thought I'd let you Brits know how sweet you had it.

.

I don't understand why you don't buy in the UK given the better spec and favourable exchange rate?

I haven't ruled that out yet, but I wouldn't save all that much after the taxes payable in Ireland. The way it works is you pay the ex VAT price in UK, then you pay VAT (at the Irish rate, 21.5%) on the Euro equivalent of whatever you paid the UK dealer. Then you have to pay VRT (vehicle registration tax - an extra tax on all cars sold or brought into Ireland). The VRT rate depends on the emissions level of a car. For the 1.4 it's 20% (28% for the 2.0TSI). So you pay 20% of the Irish retail price of the car (it's also payable on any extras).

So it work out like this: Nicely specced 1.4 ex VAT for about £18,500. That's about €20,800. VAT on that at 21.5% is €4,472. VRT comes to about €6,500. Add these up and you get €31,772 (£28,300). So the saving from buying in UK and importing is about €3k or so, depending on the exchange rate you get at the time.

I'm not sure if it's worth the hassle. I'd have to sell my current car privately, as a UK dealer wouldn't take it as a trade in. Selling used cars at the moment is a nightmare - I might end up getting next to nothing for it, while a dealer in Dublin has actually offered me a reasonable price for it as trade in.

I just dunno what to to!

[heavymetalmayhem]

Blimey I didn’t realise you were taxed so heavily! Thanks for explaining.

[easybreeze]