Cornering technique - different for fwd vs rwd?

[havoc]

There is a rather long (and increasingly torturous! ) thread where this concept has raised it's head.

More specifically, the fact that in an fwd car you can only be truly balanced through a corner with turn-in commitment (i.e. when pressing on), and even then the car tends to an understeer-biased attitude. Conversely a rwd car is balanced throughout all phases of a corner, and you have options as to how you enter the corner.

So, to the experts of the AD forum:-
- is the above always true? Even for a diff-equipped fwd car?
- would you change the way you drove through a corner depending on whether the car was fwd, rwd or 4/awd?

Any other thoughts?

Thanks,

M.

[WhoseGeneration]

havoc said:

There is a rather long (and increasingly torturous! ) thread where this concept has raised it's head.

More specifically, the fact that in an fwd car you can only be truly balanced through a corner with turn-in commitment (i.e. when pressing on), and even then the car tends to an understeer-biased attitude. Conversely a rwd car is balanced throughout all phases of a corner, and you have options as to how you enter the corner.

So, to the experts of the AD forum:-
- is the above always true? Even for a diff-equipped fwd car?
- would you change the way you drove through a corner depending on whether the car was fwd, rwd or 4/awd?

Any other thoughts?

Thanks,

M.

Firstly, all cars need a diff, whatever drive configuration, to be able to corner.
Some have more than one, AWD needing this.
Did you mean some form of limited slip or torque biasing for FWD?
Simply, in an AD sense, cornering techniques are no different, whatever the drive configuration.
AD on the public road, that is.
Track or competition may be a different matter.
Having said that I'd always rather have an AWD car rather than RWD or FWD on the public road.

[Pork_n_Beem]

Surely the static weight distribution of the car is more important than whether its FWD or RWD. Some FWD cars are very well balanced no matter how you enter the corner, some are really bad, so i guess it depends on the car.

Cars can corner without diffs but prefer not to :-)

[Steve Rance]

Are you asking from a road or track perspective? From a road perspective it shouldnt make any difference as you should be a long way off of the edge of any car's performance window. For the track, it depends of many different factors, weight distribution, chasis spec, geometry, tyres, power, diff set up etc.. if the set up of the car is good then in very simple terms a driver will adopt a technique which best manages the weight transfer loads of the car during cornering but again it is nor that straight forward as if the car has relaively high power output he will adopt a style that enables him to deploy that power as early as possible, if he has low power, he will try to carry more speed into the corner. Then there is a 911 which requires a very specifc technique. Not a question that is easy to answer without more information

[havoc]

Thanks.

WG - yes, torque-biasing diff, sorry. Out of interest - why the preference for AWD - personal choice, or something inherent in the layout?

And why would the technique be the same regardless of layout, if the inherent (cornering) balance of the car is altered by the drivetrain?

[RobM77]

Steve's probably quite right for road driving, although for my own personal satisfaction (and in some ways safety of course) I like a car to be balanced, with me behind the wheel generating as high a limit as possible (by being smooth, balanced etc as I would on track), and preferably staying as far from that limit as I see fit in any given corner - all the way through the corner at each phase. In other words I'm sympathetic to the limit and I wouldn't, for instance, drive a 911 in the same was as an M3 through a corner, even at low speed on the road. To drive a 911 in the same way as an M3 on the road, to follow the M3's speed profile and control usage through the corners, would mean being closer and further from the limit through a corner, and whilst you may instantly say that it doesn't matter at low speed, it does have a small impact on safety (some aspect of road safety is always going to be directly proportional to a car's distance from the limit at any given time), but most importantly, it has an impact on my satisfaction as a driver, and if I didn't have that satisfaction element on the road I'd just be driving a Micra!

To use an analogy, if you lock me in a soundproof room with a guitar away from prying ears, I'll still play in tune, and if you detune my guitar or give me a guitar I'm not happy with I won't want to play it. The same goes for cars. Even if I'm driving slowly and otherwise safely and not around other cars, I want to be in a car that I enjoy driving and I want to drive it in a certain way, even at low speed. Ergo, in answer to Havoc's original question, yes, I drive each car differently, being sympathetic to how that car is best handled. If I didn't care about this, I shouldn't see why I'd even bother buying a sports car.

I realise when I try and state this sort of thing on this forum people fail to understand what I mean and huge arguments ensue, but before you all read something different into my post to what I've actually said, please this time just slow down and read what I've read properly. Thank you.

[waremark]

RobM77 said:

I wouldn't, for instance, drive a 911 in the same was as an M3 through a corner, even at low speed on the road.

As you know, I am one of the 'Adopt a driving technique which works in any car' folks - and this does not prevent me getting a great deal of enjoyment from driving sports cars. However, I am delighted to be told about what I am missing.

So tell us how you would drive a given road bend in 911, M3, Mini, and Elise (by all means add a 4wd example if you think that any one can be representative of the configuration).

[Steve Rance]

Yep, im with you on that. From a road perspective, I drive everything the same way. I think that on the road you should be nowhere near threashold so I can see that a one style fits all approach would work. From a ADI perspective, I presume that formalising a standard technique enables the driver more capacity to concentrate on visual awareness?

[havoc]

Wondered how long before you'd find this thread...was interested in an AD perspective vs your 'track biased' (hope I'm not overstating that?) perspective.

FWIW, I think your comment above is accurate - I too would drive FF vs FR vs F4 vs MR or RR differently through a corner, whether pressing on or not. (More so when hooning than not). I was just intrigued by your comment on the other thread which suggested that the 'technique' was the same for all layouts.

I also think (more suitable in this fora than the other thread) that personal preference has a lot to do with it - from a purist perspective (such as yours) rwd has clear advantages. But from a personal perspective an individual driver may be just 'more comfortable' with the way fwd or (the various types of) 4wd behaves. Hell, even fwd has a range from "safe Audi understeer" through to "classic French tail-happy". And in that context rwd just might not suit every driver, even if they take the time to 'learn' it.

[Steve Rance]

havoc said:

Thanks.

And why would the technique be the same regardless of layout, if the inherent (cornering) balance of the car is altered by the drivetrain?

Its only a real issue if you are driving near threashold and you shouldn't be anywhere near that on the road. If you drive a modern car around a corner at say 30mph which is capable of navigating the same corner at 60mph, it's drivetrain will not effect your driving style whatever the layout is. At 55 - 60mph it obviously becomes relevant. Anyway, almost all cars are set up to default to understeer whatever thier configuration. You can provoke oversteer with the throttle on a relatively high powered rwd or mid engined car (to a lesser extent) but thats basically poor throttle control and again you shouldn't be driving that way on the road.

[218g]

RobM77 said:

(some aspect of road safety is always going to be directly proportional to a car's distance from the limit at any given time)

Positively correlated perhaps, but I'm not sure about directly proportional?

[RobM77]

218g said:

RobM77 said:

(some aspect of road safety is always going to be directly proportional to a car's distance from the limit at any given time)

Positively correlated perhaps, but I'm not sure about directly proportional?

My mistake from typing in a rush, yes, positively correlated.

[RobM77]

Steve Rance said:

Yep, im with you on that. From a road perspective, I drive everything the same way. I think that on the road you should be nowhere near threashold so I can see that a one style fits all approach would work. From a ADI perspective, I presume that formalising a standard technique enables the driver more capacity to concentrate on visual awareness?

This is often quoted on here, but how far are you AD guys from the point of peak grip (aka "the limit") when you're driving? Are you really so far from it that the 5-10% variations that we're talking about here won't matter? By that I mean the additional contributions that dynamically sympathetic driving would make to safety (rev matching, balancing the car etc).

waremark said:

RobM77 said:

I wouldn't, for instance, drive a 911 in the same was as an M3 through a corner, even at low speed on the road.

As you know, I am one of the 'Adopt a driving technique which works in any car' folks - and this does not prevent me getting a great deal of enjoyment from driving sports cars. However, I am delighted to be told about what I am missing.

So tell us how you would drive a given road bend in 911, M3, Mini, and Elise (by all means add a 4wd example if you think that any one can be representative of the configuration).

Essentially, I do my best to balance the car throughout the corner, and this obviously changes depending ont eh weight distribution of the car.

In something like my 320d or an M3, the technique is pretty standard; I exchange braking for steering on turn-in in a manner that gives the car balance, hold that balance through the corner on a steady throttle with the steering still, and then exchange steering for acceleration as I leave the corner. In the Elise, because of the light front end, to avoid the danger of getting too close to the limit at the front and to retain balance, then I would alter the timing of those two aforementioned exchanges; most notably the turn in. Nobody's going to aargue that cornering at 50:50 grip F:R is safer than 60:40. I wouldn't trail brake on the road (such a technique is designed to reduce lap times, not increase safety), but I would hold on the brake subtley longer to load the front up and create more of a balance. In the Elise, if you just turn into a bend on a steady throttle (as per IAM technique, but interestingly not the very well known AD coach I've had a day with), you get quite a dangerous (relatively) instability, with the car totally out of balance and tending towards understeer (not understeering - but with the balance very much biased towards this). In extremis on track, if you drive an Elise like this then you get what plagued Clarkson on his now infamous test drive (see below), but at sensible road speeds, you just won't have the balance to drive through a corner with poise, satisfaction and yes, to a certain extent, safety. You'll also wear out your front tyres really quickly, so poor drivers in Elises are running round with part worn rears and replacing the fronts constantly, which is never good for aquaplaning performance!

My beloved Elise S2 111S being reviewed on Top Gear showing out of balance for u/steer, and then o/steer:.

http://www.youtube.com/watch?v=lJwhhmv0l8c

Turning in "flat" gives understeer - watch from 3m06s.
Gavan Kershaw turns up at 4m30s to do some oversteer.

The correct technique is halfway between the two: http://www.youtube.com/watch?v=xbKWGhQz9vc&NR=...

Imagine these videos slowed right down on the road at a safe speed on the average B road. Visually, the average bystander wouldn't notice any difference between any of them, and perhaps even from within the car. However, it is unarguably safer to corner with a balance of 50:50 grip front to rear than it is at the same speed at perhaps 70:30 like Clarkson would do. The reason is the 70% at the front - he'd only be 30% from the limit. Why not just drive slower? Perhaps 50% of the limit? Well, the balanced driver can do that too, and mathematically he'll always be further from the limit than the out of balance driver because he's sharing the grip front to rear. I would contest that road speeds are not so unbelievably slow that this doesn't matter.

Edited by RobM77 on Sunday 9th January 16:13

[thiscocks]

waremark said:

RobM77 said:

I wouldn't, for instance, drive a 911 in the same was as an M3 through a corner, even at low speed on the road.

As you know, I am one of the 'Adopt a driving technique which works in any car' folks - and this does not prevent me getting a great deal of enjoyment from driving sports cars.

I would agree with that. All road cars have been set up so a fair variation of driving styles will work with getting it down the road safely.

You have to be going fairly quickly for Robs 'balancing' tecnique to come into effect so is not really benificial for the road. Most roadcars have understeer dialed into them (EVEN rwd) so to get any sort of neutral handling out of them you'd have to be going for it on a track for your tecnique to come to any benifit.

[RobM77]

thiscocks said:

waremark said:

RobM77 said:

I wouldn't, for instance, drive a 911 in the same was as an M3 through a corner, even at low speed on the road.

As you know, I am one of the 'Adopt a driving technique which works in any car' folks - and this does not prevent me getting a great deal of enjoyment from driving sports cars.

I would agree with that. All road cars have been set up so a fair variation of driving styles will work with getting it down the road safely.

You have to be going fairly quickly for Robs 'balancing' tecnique to come into effect so is not really benificial for the road. Most roadcars have understeer dialed into them (EVEN rwd) so to get any sort of neutral handling out of them you'd have to be going for it on a track for your tecnique to come to any benifit.

That is purely a matter of opinion of course . Whilst I admit the safety benefits of balancing a car properly are marginal, it's only like choosing to rev match. Just as a non rev matched downchange makes little difference to road safety at low speed, it makes me cringe to hear it. Same with cornering balance, or steering technique etc; it makes me cringe to see someone out of balance in a corner, or using the steering out of sympathy with the throttle. Rev matching probably makes it into the IAM syllabus not because it makes a bigger difference than balanced cornering and other techniques, but because it's easier to explain and teach.

I must admit though, I do struggle to understand why someone would pay a premium for a GT3 over a C2 or an M3 over a 330ci if they don't get stuck in and interact with a car in a corner. I'm not talking about high speeds, just enjoy things at low speed. If you're driving a C2 in exactly the same manner as a GT3, then why not just buy a C2? Also, surely someone sensitive enough to detect and enjoy the different suspension and diff of an M3 over a 330ci is going to want to drive with sympathy to those facets surely to get the most out of them? Just some thoughts there off the top of my head, not a definitive statement.

[thiscocks]

RobM77 said:

thiscocks said:

waremark said:

RobM77 said:

I wouldn't, for instance, drive a 911 in the same was as an M3 through a corner, even at low speed on the road.

As you know, I am one of the 'Adopt a driving technique which works in any car' folks - and this does not prevent me getting a great deal of enjoyment from driving sports cars.

I would agree with that. All road cars have been set up so a fair variation of driving styles will work with getting it down the road safely.

You have to be going fairly quickly for Robs 'balancing' tecnique to come into effect so is not really benificial for the road. Most roadcars have understeer dialed into them (EVEN rwd) so to get any sort of neutral handling out of them you'd have to be going for it on a track for your tecnique to come to any benifit.

That is purely a matter of opinion of course . Whilst I admit the safety benefits of balancing a car properly are marginal, it's only like choosing to rev match. Just as a non rev matched downchange makes little difference to road safety at low speed, it makes me cringe to hear it. Same with cornering balance, or steering technique etc; it makes me cringe to see someone out of balance in a corner, or using the steering out of sympathy with the throttle. Rev matching probably makes it into the IAM syllabus not because it makes a bigger difference than balanced cornering and other techniques, but because it's easier to explain and teach.

I must admit though, I do struggle to understand why someone would pay a premium for a GT3 over a C2 or an M3 over a 330ci if they don't get stuck in and interact with a car in a corner. I'm not talking about high speeds, just enjoy things at low speed. If you're driving a C2 in exactly the same manner as a GT3, then why not just buy a C2? Also, surely someone sensitive enough to detect and enjoy the different suspension and diff of an M3 over a 330ci is going to want to drive with sympathy to those facets surely to get the most out of them? Just some thoughts there off the top of my head, not a definitive statement.

I agree. All of the people I know of who buy new M3s(and the like) have pretty much no clue/interest in its technical prowess. More interest in looking cool driving through town- The wheelz look wikid init!(when they are smashing my teeth out over pot holes) -But this is a diferent topic!

[Dr Jekyll]

RobM77 said:

Just as a non rev matched downchange makes little difference to road safety at low speed, it makes me cringe to hear it. Same with cornering balance, or steering technique etc; it makes me cringe to see someone out of balance in a corner, or using the steering out of sympathy with the throttle. Rev matching probably makes it into the IAM syllabus not because it makes a bigger difference than balanced cornering and other techniques, but because it's easier to explain and teach.

There is the point that a non rev matched gearchange is bad for the clutch and uncomfortable for the occupants. A colleague of mine doesn't rev match and I practically get whiplash on her downchanges. Whereas being 'out of balance' on a corner is undetectable to most of us. Unless it's something extreme like cornering on a trailing throttle.

[RobM77]

Dr Jekyll said:

RobM77 said:

Just as a non rev matched downchange makes little difference to road safety at low speed, it makes me cringe to hear it. Same with cornering balance, or steering technique etc; it makes me cringe to see someone out of balance in a corner, or using the steering out of sympathy with the throttle. Rev matching probably makes it into the IAM syllabus not because it makes a bigger difference than balanced cornering and other techniques, but because it's easier to explain and teach.

There is the point that a non rev matched gearchange is bad for the clutch and uncomfortable for the occupants. A colleague of mine doesn't rev match and I practically get whiplash on her downchanges. Whereas being 'out of balance' on a corner is undetectable to most of us. Unless it's something extreme like cornering on a trailing throttle.

Fair point

[havoc]

Dr Jekyll said:

RobM77 said:

Just as a non rev matched downchange makes little difference to road safety at low speed, it makes me cringe to hear it. Same with cornering balance, or steering technique etc; it makes me cringe to see someone out of balance in a corner, or using the steering out of sympathy with the throttle. Rev matching probably makes it into the IAM syllabus not because it makes a bigger difference than balanced cornering and other techniques, but because it's easier to explain and teach.

There is the point that a non rev matched gearchange is bad for the clutch and uncomfortable for the occupants. A colleague of mine doesn't rev match and I practically get whiplash on her downchanges. Whereas being 'out of balance' on a corner is undetectable to most of us. Unless it's something extreme like cornering on a trailing throttle.

Agreed.

Re: 330/M3 or C2/GT3 - ignoring the power and ride-comfort issues, the big thing for me (330/M3 at least - imagine the Porkers to be similarly related from reviews I've read - not had the pleasure of a GT-anything, sadly) is the precision and the feedback - plus the M3 feels more 'up for it' than a cooking 3-series. But yes, half of owners probably buy them for the badge...

[cosicave]

Yes havoc, To answer your initial question directly, there are several factors at play here. Propelling vehicle from opposite ends influences the turning moment at the centre of mass, which is attempting to rotate vertically about the point any driving force (or braking force) is applied. And although this is independent of lateral moments at the centre of mass, initiated by steering, a driver must adjust technique in order to maximise traction for the longest possible time through and out of the corner.

The net result is that under acceleration, the rear wheel drive car experiences more grip at its driven wheels, whilst the front wheel drive car experiences less.

It is therefore vital to maximise weight towards the front with FWD, and to be careful to avoid 'unloading it' through the turn which causes the trademark understeer associated with FWD acceleration.

The RWD car on the other hand, needs loading up at the rear earlier in order to maximise the potential for early acceleration out of the corner.

Depending on the corner involved, this may even require a driver to take a different line into, through and out of it, although this may not always be obvious, particularly for the spectator.