AWD v FWD v BWD

2005 Need for Speed Most Wanted

AWD v FWD v BWD

Postby vanguard » 26 Mar 2006, 07:16

i realized the reason why my porsche has such terrible handling (even though its stat indicate otherwise) is because it is back wheel drive. my mitsubishi lancer has much better handling and it is all wheel drive. does the wheel drive significantly alter the handling of a car?


what are your experiences on this?
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Postby HKSfan » 26 Mar 2006, 10:50

FWD cars do not drift and tend to understeer a bit.

AWD cars accelerate quickly from zero and have much traction offroad. They mostly neither under- nor oversteer, but they sometimes do both (of course not the same time)

RWD cars are likely to slide, which can be helpful going around sharp turns. However, they have little traction offroad and when they stand, that's a disadvantage when the police tries to box you in.

Fact:
-FWD and AWD cars have a more predicable handling than RWD cars.
-AWD cars are the best ones for police pursuits.

-Exceptions from the RWD cars are the Porsche Carrera GT and the M3 GTR. The GT has got a monstrous acceleration, both have as much traction offroad and from zero as the AWDs. Additionally, the BMW also handles like an AWD.
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Postby Tejas McHawan » 26 Mar 2006, 11:04

Yes.It should work
Its better use FWD orAWD :wink:
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Postby Toshiro » 26 Mar 2006, 19:36

RWD: Drift
AWD: Traction
FWD: Balanced
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Postby DarrenR21373 » 27 Mar 2006, 22:29

^ Agree. I love drifting my maxxed RX7. Pity it tops out at 197 MPH at present (only a 5 speed box by Blacklist #6. Hope I get a 6th gear soon!)
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Postby Toshiro » 28 Mar 2006, 03:52

Most of the high-end cars are RWD (Supra, FD, Porsche), as it is easier to push than to pull. One exception is the Nissan Skyline, which is a AWD.
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Postby TheStig » 28 Mar 2006, 06:50

Alot of Porsche 911's are AWD

The Carerra 4 and Carerra 4S are AWD the 911 Turbo and Turbo S are AWD.

And ofcouse the Porsche Cayenne :wink: only the highest Porsche (Carerra GT) is RWD

Don't forget cars like Subarus (all of them) are AWD, and the Evo's are also AWD.

and in the Exotic class:

Lamborgini Murcielago and the Lamborgini Gallardo are also AWD cars.

The reason why RWD is a good racing concept cause the weight of a car is always on the rear wheels when accelerating, so with a RWD you will give yourself more traction,

what happens in every car when accelerating is like said the weight is on the back, so the front goes up abit (every car does that, but it increases with the amount of trottle you give it.)
with that the problem comes with FWD cars cause they will loose traction cause the weight is shifting to the back of the car.


BTW the Nissan Skyline GTR is a Hybrid not a full AWD car, cause in normal use it is a RWD car, only when in corners and in low traction at the rear wheels the front Wheel drive will kick in.
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Postby GINIX_2007 » 28 Mar 2006, 07:05

@ Stig

Nice Info on the Skyline GTR i never knew that! But does it perform like tat in the game?
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Postby TheStig » 28 Mar 2006, 07:26

Not as far as I know, it is really hard to get that in a game, I asume they made it a full AWD car for games. cause you have to make a specific program that mimics the skylines computers.

Do some searching for it, there are some movies from Top Gear where they test the R34 (several tests) and they explain some of the stuff there also and they explain it pretty good and simple
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Postby FreelancerMar » 28 Mar 2006, 08:16

Another thing that must be considered is the Location of the engine on some of these cars. The Vast Majority of Porsche's are Mid/Rear Engined cars which puts the engine weight over the Rear tires. Its the Same with the Lambo's and the Ford GT. The way you setup the performance tuning of the ride is also a consideration.
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Postby GINIX_2007 » 28 Mar 2006, 17:01

I LOVE TOP GEAR!!! any way i will check it out thanks again Stig. By the way u wouldnt happen to be that mystry driver from the show would u :?: :?
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Postby Maverick2K4 » 28 Mar 2006, 18:24

FreelancerMar wrote:Another thing that must be considered is the Location of the engine on some of these cars. The Vast Majority of Porsche's are Mid/Rear Engined cars which puts the engine weight over the Rear tires. Its the Same with the Lambo's and the Ford GT. The way you setup the performance tuning of the ride is also a consideration.


Just to be clarify a bit more, most Porsches are rear engine, rear wheel drive. not mid-engine. If you know the basics on how to control each type of driveline, then controlling the Porsche should be no problem. Stig is right, though. The Porsches that are featured in Most Wanted are AWD with the exception of the Carrera GT and the Cayman. When you hit the speedbreaker and you're starting to drift, make sure you know where to downshift, or else you'll lose your torque band and won't be able to hold your drift. Another key element is your steering. Start to counter-steer it at the apex of the corner. Don't turn the wheels to the extreme if you want to hold a longer drift and get better angle; ease into it. That's what I do when I drift my 911 Turbo S in MW.
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Postby TheStig » 28 Mar 2006, 18:37

The 997 Carerra S in MW is also RWD so only the Turbo S is a AWD car :wink:
the Carerra 4S is the AWD version of the Carerra S :wink:
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Re: AWD v FWD v BWD

Postby SkeeteRX7 » 28 Mar 2006, 18:41

vanguard wrote:i realized the reason why my porsche has such terrible handling (even though its stat indicate otherwise) is because it is back wheel drive. my mitsubishi lancer has much better handling and it is all wheel drive. does the wheel drive significantly alter the handling of a car?


what are your experiences on this?


1: It is called RWD not BWD. Also, the Porsche 911 has harsh oversteer because it is rear-engined, putting less balance onto the front in turns. If you are a skilled driver, Porsche 911's are some of the worlds best handling cars. If you think the 997 or 996 are hard to handle, try out the 1973 911 Carrera RS in NFS: Porsche Unleashed. It's almost impossible to control. Some rear wheel drive cars have excellent handling, such as the Mazda RX-8 and RX-7 and the Porsche 944, because they have the drivetrain in the rear and the engine in the front, allowing for near-perfect 50-50 weight distribution; and mid-engine, rear wheel drive cars such as the Renault Clio V6 and Lotus Elise handle well because they stick to the road with a low center of gravity. The thing about handling a rear engine, rear wheel drive car is to not turn while braking, or the front of the car will lose control because there is no weight to balance out the front wheels from viciously flailing. If one can learn to glide around corners, a Porsche will be your first choice in a race.
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Postby DarrenR21373 » 28 Mar 2006, 19:44

GINIX_2007 wrote: By the way u wouldnt happen to be that mystry driver from the show would u :?: :?


I actually know for a fact who Top Gear's TheStig really is (in fact, both of them, although I can't remember the first one's surname). They were unveiled by the Daily Express newspaper. And I have to say, I was really disappointed when I found out who it wasn't 8)

I won't post it here, I don't want to spoil your guessing. :D

Though, of course, there is only one real TheStig, and he is Admin here :)
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Postby Maverick2K4 » 28 Mar 2006, 19:47

Ah, gotcha Stig. My mistake.
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Re: AWD v FWD v BWD

Postby mjdude23 » 29 Mar 2006, 00:50

SkeeteRX7 wrote:Some rear wheel drive cars have excellent handling, such as the Mazda RX-8 and RX-7 and the Porsche 944, because they have the drivetrain in the rear and the engine in the front, allowing for near-perfect 50-50 weight distribution

my modded out Mazda RX-8 in NFSU2 has horrable handling :roll:
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Re: AWD v FWD v BWD

Postby GT3x24x7 » 29 Mar 2006, 02:55

SkeeteRX7 wrote:.. the Porsche 911 has harsh oversteer because it is rear-engined, putting less balance onto the front in turns.

You are far more likely to get understeer in an RR (rear engine, rear drive) car like many Porsches, since there is very little weight over the front wheels. Oversteer is very hard to induce for the same reason. However, once the rear does finally break traction, it is very hard to correct because of rear weight and the momentum this produces.

SkeeteRX7 wrote:.. they have the drivetrain in the rear and the engine in the front, allowing for near-perfect 50-50 weight distribution..

FR (front engine, rear drive) cars do not have a 'near perfect 50-50 weight distribution', they are extremely front heavy. For this reason, it is more likely that this configuration will oversteer in an overcooked turn since there is much less weight over the rear.

SkeeteRX7 wrote:.. mid-engine, rear wheel drive cars such as the Renault Clio V6 and Lotus Elise handle well because they stick to the road with a low center of gravity..

MR (mid-engine, rear drive) cars 'stick to the road' because they have the 'near perfect' weight balance that you attribute to FR cars. The engine is close to the centre point of the chassis, meaning a much more even distribution of weight to both the front and rear wheels.

Centre of gravity is a different beast entirely and is not specific to any drive type. This relates largely to the vertical weight distribution in the car. Car height, ground clearance, engine mount height all contribute to this and it affects a car's tendency to roll in turns. Any drive type can have a high centre of gravity, any drive type can have a low centre of gravity.

SkeeteRX7 wrote:.. The thing about handling a rear engine, rear wheel drive car is to not turn while braking..

The thing about driving ANY car is not to turn while braking, in normal circumstances. The process should always be brake, weight shift, turn in, coast to apex, accelerate out. However, in cases where braking was insufficient and understeer is encountered, light and/or brief braking mid-turn to shift weight to the front and regain front traction is effective. Again, this applies to any drive type.



If you're trying for a clean line, there should be NO understeer and NO oversteer. The fastest way through is to keep traction on all four wheels at all times. On turn entries, understeer is an indication of insufficient braking, while oversteer indicates overbraking. On turn exits, accelerating too hard or too early will produce understeer in rear heavy cars and oversteer in front heavy cars.

By knowing the drive configuration of the car you're in, the principles of weight shifting and with a bunch of practice, you can pretty much handle any turn a track might throw at you quickly and efficiently. Resorting to the 'blame the tools' mentality exhibited in the first post might help vanguard stay in the cars he can control, but it sure doesn't build skill.
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Postby SkeeteRX7 » 03 Apr 2006, 17:26

Sorry GT. I know mostly about FF, FR, and AWD. Dont make me feel like a n00b!
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Postby jeffr » 06 Apr 2006, 11:23

FR (front engine, rear drive) cars do not have a 'near perfect 50-50 weight distribution', they are extremely front heavy.
2006 Corvette Z06 - front engine - rear wheel drive, weight distribution 51-49, that's pretty close to 50-50.

What causes understeer or oversteer is the relative grip between the front and rear end of a car. The lateral grip front / rear bias can be adjusted by making one end of the car relatively stiffer (with respect to the weight distribution), since this puts more of a load on the outer tire at the stiffer end, and unlike solid objects, the grip from a tire doesn't increased quite as much as the increase in downforce, so there's some loss of grip at the stiffer end when cornering.

The front to rear weight bias mostly affects what happens once a car does start sliding. On a downforce car, the weight ratio isn't quite as cricical, as you can just add more downforce to the heavier end and just deal with it for the few low speed turns at most tracks. Formula 1 cars are rear heavy and use a lot of rear wing as compared to the front.

In order for the rear tires of a car to generate lateral force, there has to be some "slip angle", the tires have to be angled inwards of the direction they are traveling. This means that a car has to be yawed inswards (oversteer) relative to the direction it's traveling in order to turn at it's best. Since the front tires are turned inwards relative to the car when turning in most situations on pavement (not including drifting here), they have more slip angle than the rear tires, so the rear tires have some traction left over for power from the engine. This is why almost all high powered racing cars are rear wheel drive. For example, Formula 1 tried 4 wheel drive, but the amount of power that could be applied to the front tires was so small that it wasn't worth the increase in unsprung weight on the front tires. AWD doesn't work well untill you get into sedan type cars that are heavy enough that the unsprung weight factor at the front end isn't an issue.

Slip angle can occur from just flexing of the contact patch, but maximum cornering force occurs with some slippage. Modern racing traction control systems are setup to allow 8% to 12% slippage.

brake then corner
It's quicker if you can enter a corner faster, then slow down as you approach the apex. You can use the brakes, but generally the loss of speed from cornering forces and/or lifting on the throttle is enough to slow a car down. How much of this is done depends on the power and turning radius. In the case of a low powered car on a large radius turn, then you take the shortest path at a near constant speed. In the case of a high powered car on that same turn, you enter faster, slow as you approach the apex, with the apex as the slowest speed, the accelerate out of the turn. In this case you want some oversteer reaction to keep the car turning inwards while it slows so it doesn't plow off track.

Since NFS:PU was mentioned, you can setup the 1995 911 turbo awd to oversteer by setting front pressure to 45psi (maximum grip in the game), and rear tire pressure from 41 to 43 psi (a bit less grip). The car will then oversteer and slow down by just lifting on the throttle. You need the toe slider set all the way right. In the case of the 2 wheel drive 911's, like the 1973 911, the game has set the front rear grip bias too high, the rear grip is too relatively low, and results in too much oversteer reaction. To cure this, you need to set the toe slider all the way left. In NFS:PU the toe slider adjusts the front to rear grip bias. In real life this same effect would be done by making the front end of the car stiffer than the rear, but NFS:PU accomplishes the same effect via the toe in/out adjustment, left for understeer, right for oversteer.

Here is a sample picture of the racing line at Willow Springs, showing the difference between low and high powered cars on the larger radius turns. Note that in turn 3 and turn 4, the best line is one where the car is slowed down very much, then does a tight radius turn, to allow a good near straight line acceleration out of the turn. These two corners are classic examples of slow in, fast out.

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Postby SkeeteRX7 » 06 Apr 2006, 14:27

Also, my father had a beetle and has driven 911's, and said that they all oversteer because of having less weight in front. I checked on a website and it checked out
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Postby GT3x24x7 » 06 Apr 2006, 15:09

Define 'oversteer'.
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Let me rephrase my argument,

Postby SkeeteRX7 » 06 Apr 2006, 17:48

Oversteer is the phenomenon ocurred in an automobile when the rear tires have a loss of traction during a cornering situation, thus causing the rear of the vehicle to head towards the outside of the corner. This happens when one pulls a rear engined car hard into a turn.

The disadvantage of the RR configuration is that placing the engine outside the wheelbase creates significant problems for handling as, when the car begins to slide on a corner, the end of the car will tend to want to swing wide and overtake the front - especially under braking. This tendency is referred to as oversteer and creates potential safety issues in racing applications as well as for ordinary drivers on wet or icy roads, although such behavior is desirable in drifting, a motorsport based on intentional oversteer.

In addition, even though the rear wheels benefit from the additional traction the added weight of the engine gives, the front wheels still need traction in order to steer the car effectively. For this reason, a RR layout car can also be prone to understeer. Most manufacturers have abandoned the RR layout apart from Porsche who has gradually developed their design with improvements to the suspension as well as electronic aids to reduce the shortcomings of the layout to acceptable levels.
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Postby GT3x24x7 » 06 Apr 2006, 18:35

Good, we're talking about the same thing. So many people confuse oversteer and understeer.

"when the car begins to slide".. oversteer occurs. Of course - the rear is heavier and traction is already lost. Momentum takes over at that point. As I said in my original post. However, traction is likely to be lost at the front end first (ie: understeer) because of the rearward weight ballance of the RR setup.

The fastest line requires little or no loss of traction. If you manage to get an RR car oversteering, you were way too hot to begin with. And yes, at that point, you're gonna be in a whole load of white knuckled trouble.
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Postby SkeeteRX7 » 06 Apr 2006, 21:41

Yep, thats why a beginner should never opt for a Porsche 911, especially a Carrera S. At least the Turbo S has AWD. You have to learn how to brake accordingly.
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