EvilBevel

2.5 G is defo downforce related (and car weight), but even cars with a small front/rear lift at 200 km/h(like an Impreza MY00) can corner upto 1.2 G in the dry (see Sport-Auto tests).

Should look it up as it's explained in "Drive to Win", but wasn't this to do with the fact there's not only mechanical but also chemical locking ?

Claudius

This is just plain wrong! You dont get any front grip in a RWD and if you would accelerate as early as with an AWD, you would go straight!

ex-webby

Hi Claudius

Is that your entire argument / basis of understnading as to why they are not more efficent / performant in any other circumstances?

What ABOUT understeer? Are you saying that putting power to the fronts will reduce understeer? I hope not.

Just because of the weather, lack of experience on a bend and that the road may not be clean, does that mean that you drive your AWD car as though you are on a rally? Remember that I said AWD is probably better / easier for the inexperienced driver in real world conditions.

Is that the only reason? Are you honestly trying to tell me that the cream of all performance cars are reduced in weight enough (meaning stripping everything on the car that is not necessary) that they would even reduce the performance of the car (which is what you are saying it would do) by making them RWD instead of AWD just so it can be lighter?

If so, are you saying that this therefore makes it faster? If so, are you saying only in a straight line? If so, are you saying that the likes of Lotus, Ferrari, McLaren, etc are only interested in straight line performance?

Come on Claudius, put a bit of weight behind your arguments rather than taking pot shots at me from behind my statements.

All the best

Simon

ex-webby

claudius

Unfortunately, you clearly just do not understand what's going on. Could you give us some idea of what experience / expertise you have to bring you to this conclusion?

Some of the most respected and successful vehicle manufacturers and motorsport companies in the world will be VERY interested to hear this revelation.

Can you explain WHY this will happen, rather than just stating that it will?

Cheers

Simon

Claudius

Hi Simon

What I'm saying is that given the same entry speed into a corner, if I floor my former M3 before the apex, it will understeer.
If I do the same thing in my Evo, the front diff locks up and pulls me into the direction I indicate.

roee

I reckon that when you corner, you're using all the available grip of the front tires, and only part of the grip of the rear tires.

Imagine a car with similar geometry both front and rear, same suspension, 50/50 perfect weight distribution. Now imagine it cornering - what side would break traction first? I guess the front tires will, as they have to cope with more combined force. That means they both effecitvely brake (due to being in an angle relatively to the cars direction of movement) and provide lateral grip (which I believe is the same between the fronts and the rears..?).

The grip of the fronts is almost fully utilized by the cornering forces (which is operating in two planes), hence they have very little longitudinal grip left availiable for propelling the car forward.
RWD will just power the rears which aren't nearly as used as the fronts are and got lots of longitudinal grip left, while AWD will make the front break grip and FWD will be the worst..

So Simon, for putting an Impreza sideways - an Impreza specifically - without active differential tricketry, i.e. a standard 99 GT, you have to first reduce traction at the rear to the point of almost oversteer, like using flick or trail braking and then apply power? You can't just power oversteer like in a RWD?

Claudius

Absolutely

LOL! You are trying to get as mean as me, implying the person you are talking to cant drive Remember it's all just for a bit of fun / banter between Jap car enthusiasts

Claudius

I meant rally car enthusiasts.

ex-webby

Claudius

We're talking about vehicle dynamics, not your "former M3".

Maybe your front tyres were less than perfect, baybe the suspension geometry was off, maybe you weren't driving it properly, who knows. That is hardly the evidence you should take to base an argument on.

roee
Agreed 100%. Did I say something that made you think otherwise?

Cheers

Simon

ex-webby

Claudius

I take the advice I give (and in-fact any advice given) on scoobynet very seriously. There is nothing worse than hearing some advice from someone who seems to know what they're talking about and taking it as gospel only to find out it was innacurate or just completely wrong.

It is even worse if people make decisions based on that advice. This is why it is not always "just banter", sometimes people are reading this stuff to learn something.

All the best

Simon

roee

Cladius,

Before the apex you haven't built up enough lateral forces to use much of the overall grip of the rear tires.
Therefore, if you accelerate at this stage your won't be able to break the traction of the rears. You then just cause a severe weight transfer backwards which will load up the rear tires with grip but won't do any good to the fronts.


But that's only a guess. I haven't driven much except FWD

Claudius

OK. I am saying that they make the car lighter to make it accelerate better. Would you agree?

Therefore, it will feel slightly faster to people who mainly go straight (those M numbers and dual carriageways that get mentioned here all the time )

In addition to that, a good RWD such as an M3 always slightly let the back out in curves and can be very easily controlled with the throttle. That makes journalists or people on here say that they are more "rewarding" or that you need to be a good driver etc to be fast in them. So there's another reason: so that people (like potential customers testing the car) can easily reach the limits of the RWD under acceleration and think they're good. If they made the high performance cars AWD, many wouldnt be able to reach the limits easily...

roee

nah, just making sure

Claudius

Exactly! That's why a RWD would understeer.

You need to transfer some weight to the front, ie flick the car a little (or a lot depending on corner etc) and then power out without as much angle and lack of traction as you would get in a RWD.

Claudius

Please excuse me for giving you the concrete example you asked me for.

No, none of that. I had custom set up Bilstein monotubes, aggressive toe and camber settings. But maybe you're right, I just couldnt drive the damn thing...

You're right. Dont know why I talk about my driving experience with my crap M3 with the geometry all over the place and that I cant even drive, when I could borrow one of your physics / car dynamics books. Could I, please?

roee

Claudius, If you need/want to power before the apex then you are obviously doing something wrong. In all cases you could have gone in much faster and power after the apex, as the apex is the point in which the car has the most lateral acceleration.
Flicking the car around is creating a virtual corner apex.

I can promise you a plain AWD without active differentials would understeer even more than the M3. If you're talking about Evo with AYC, i don't think it's a fair comparision.

Claudius

I absolutely, totally 100% agree with this. That's why I try to keep the banter in the non technical sections of your forum. It's kind of sad to see the moderators here edit out swearwords and leave people say how good DS2000 brake pads are...

But I guess you also meant me. Again, please excuse me for talking crap about suspension settings first, and now about AWD being better than RWD. I shall probably get one of those fantastic M3 or Modena things (with a tubi stile exhaust for that AWESOME women-shouting-through-a-metal-tin sound) ...

Claudius

Roee

surely if you take out the LSDs, then the turbo, some of the brakes, etc, there will be a point where I'd rather have an M3!

STI MAN

Quality Thread!

This one reminds me of the Webbie V Dave T-S Tyre thread from a while ago

ex-webby

Claudius

Take a step back a minute here. You came on to this thread (As you have done on a number of threads I've contributed to) with icons and comments like "that is wrong".

There is no need to get upset when someone simply offers science and substantial experience to prove your blanket statement innacurate.

As you will probably have also noticed on one of the other threads I mentioned, I was thrilled to have learned something new from a member who knew something about suspension dynamics that I didn't.

Text books are very useful, and I've read a few, but my knowledge comes from years of experience as a test / development driver for some of the leading manufacturers / motorsport companies in the world.

Is it not possible that I may actually know a bit about what I'm talking about?

All the best, and kind regards

Simon

ex-webby

STI MAN.. now THAT was a quality argument!

roee

Claudius, AYC is a system very different than anything else, so different that the argument here is between Evo and RWD, not AWD and RWD. The Evo is set for imitating RWD behaviour.
Take a typical AWD car without that gadgetry (even though useful gadgetry ) and it wouldn't be as nearly as competent as the Evo.

Cars with active differentials are actually neither RWD or AWD, they're both. Like saying a Golf V6 is a good representitve of AWD kind, while it's definitely not. A standard Impreza is, however.

Speaking of gadgetry, the M3's DSC would surely eliminate the understeer you experience when powering before the apex. Not different than using AYC.

If AWD was so good, why manufactorers mess so much with the drivetrain for getting good handling? Why isn't that needed in RWD?

Claudius

I am in no way upset, Simon. Look:

I never said nor meant to say that you are a know-it-all who has got nothing to learn or wouldnt appreciate doing so.

Of course it is; I never said it wasnt so. I just cant understand why RWD my car understeers when I accelerate too early and my AWD doesnt and you tell me it's the opposite way around.
Talking about driving experience, I have talked about this with professionnal drivers who have won national and international rally championships and they seemed to agree with me.
I think that we do not talk about the same types of roads or something. Or maybe I'm just plain stupid in addition to being a dumbass? I would really appreciate if you could tell me in simple words where my misunderstanding comes from...

ex-webby

OK..

I think your misunderstanding comes from limited exposure / experience. You are looking at 2 isolated instances. Your M3 vs Your Scoob, both with You driving.

I am not saying you are thick or a crap driver or anything even slightly relating to that. I was just saying that your statements were incorrect.

A good way of showing the difference between cars being driven well and what a difference that makes is to look at a mixed track day.

If the drivers are average, all the scoobs, etc will eat the lotus, porsche, caterham guys alive.

The reason for this is that it takes very little skill to drive a scoob to 70% (let's say) of it's ability. The same amount of skill however could probably only muster up 45% (again, let's say) of the ability of a caterham. This does not mean that a caterham is slower, it just means that the average driver can't exploit it.

The last rally I did was the xmas stages. We won our class by a country mile and finished well ahead of evo's, scoobs, escort cosworths, etc, etc and we were driving an old RWD sierra cosworth with a stage 1 road chip in it. This does not mean that my cosworth is faster than the evo's, it just means that I was able to exploit my car's abilities more than the competition.

If your driving style suits AWD, then AWD is probably better for you. This does not mean it is more performant.

All the best

Simon

Claudius

Hmm...

So what's the big deal about driving a RWD?

On my favorite (twisty) road, I can keep the throttle open much longer than with the M3, or at least without sliding too much. And I always braked very late with the M3 (often getting the back to step outwards), to get enough weight to the front to get it in and have always accelerated as early as possible.
With my Evo, I do the same thing but I can accelerate a lot earlier and have traction.
Am I drawing the wrong conclusions from this fact? And first of all do you agree with it? I dont think you are trying to fool me, so there must be something I'm missing.

ex-webby

Claudius..

How can you be sure you were accelerating as early as possible?

Remember the evo deals with much of the driving for you with the AYC.

I'm not sure what conclusions you're drawing. I think you may well be just applying that experience to the rest of the world, and taking your evo as being the way all AWD cars handle, and your M3 as being the way all RWD cars handle?

I agree that you did what you said you did. I do not agree that this means AWD cars handle better than RWD cars.

Try re-reading what has been posted here. It's all down to tyres.

All the best

Simon

Claudius

Well, I have taken that road several times a week for years, and any earlier than when I accelerated would lift the front too much and give me understeer.

I meant an Evo 6 RS2 (had one for a year).

I now have a TME but need to junk that AYC which glues the back to the road and gives me understeer unless I am being *very* brutal on it.

Claudius

I didnt understand that. Let me re-read it.

ex-webby

What I mean Claudius is that you are surely not saying that nobody could get on the gas any earlier than you and make it not understeer?

It is possible that your driving style means that this will happen.

Cheers

Simon

Andrewza

FWIW, friction between tyre and road will apply an opposing force in one direction, which is exactly the opposite direction to the sum of the forces on the tyre. So if you're putting a force laterally on the tyre, friction will act laterally in exactly the opposite direction, however, if you add a longtitudinal force to that friction will now be applying a force somewhere between the two forces (dependant on the relative sizes of the two forces), it will also have to be applying a larger force, so if you add too great a longtitudinal force friction will be overcome and the tyre will slide. A diagram would probably help, but I can't be arsed

NB: This is just pure mechanics!