Low traction FF vs Rwd

[SidewaysGts]

Alright everyone sorry this isnt too much about drifting, more on rally.

An argument has come up and well, id like to bring it here to see what everyone has to say.

The argument is basicly this (Theres 2) Which is better for LOW TRACTION sports, ie rally over snow mud dirt rain whatever. FF or Rwd vehicles? Dont bother with Awd, the answer is obvious in that one (when it doesnt break haha).

The 2nd, which is safer? Oversteering, or Understeer. His claim is that oversteering is much safer and easier to deal with then udnersteering- its even safer for the average driver.

Please use facts, informations, whatever- opinions are fine but real stuff is always better- if you have any sources please include them as well.

BTW- I thank any and all in advance who help me with this debate.

Added: haha- i look forward to a post from Mal'

[rb20]

well id put it this way if you understeer(fwd) you have to drop off the speed which is waht is important for good times if you dont want to end up off a cliff, but you can control a sticky situation while maintaining speed in a rwd you just counter ster accordingly and you can hold a nice speed and quite often it is faster to drift through a tigh corner found in ralling-wallah a rwd can perfectly do the job no *Censored**Censored**Censored* dragging just a beautifuly controlled spin of the rear tires not a jerky handbreak turn

[SidewaysGts]

,'s and .'s are your friend.
__

I guess i should state my side of this.

I believe in low traction situations FF is better suited for racing then RWD. FFs have a number of advantages in this situation. FFs tend to be more front heavy, in situations like this speeds are lowwer and is overall acceleration- meaning hte weight stays up front a bit more and doesnt have as much of a chance to lean back. This translates to FF usually having more traction.

Another thing to consider is rwds are pushing their weight- usually a good thing. But when the front wheels are sliding easily, the weight isnt the easiest to control. if the front starts to pitch out the back wheels pushing the weight will only rotate the mass further. Just the opposite with an FF vehicle, the weight can pretty much play "follow the leader" in this situation.

Also understeer is typicly much easier to deal with then over steer. Understeer generally (And for the general driver- basedo n what they normally do). Understeer can typicaly be dealt with by just letting off the throttle and getting on the brakes, oversteer on the other hand requires good coutner-steering abilities, as well as fine brake control and throttle control. You can argue all you want that if youve got heavy understeer, getting on the brakes wont save you- but the speeds to exhibit that amount of understeer would be pretty high, if you were to oversteer at the same speeds youd like continue to slide outward- the difference really being you wont see the tree you crash into with oversteer at those speeds.

Btw the deal with comparing over/understeer is safety- not speed.

[NeveR]

Sideways, please be more correct in your posting of this debate. It has nothing to do with rally.


The argument is this:

RWD vs. FWD in poor conditions.
and
Oversteer vs. Understeer.

[Drift For Food]

For motorsports applications, especially low traction, I'd personally choose a fwd car. You can actually achieve faster speeds in a fwd than with a rwd, at least from my experience with two completely different vehicles.

Basically, for speed, a fwd is stable. This is because the center of mass of the car is behind the drive wheels. The car is essentially being drug around. You can go as fast as you can to the point where the wind resistance begins to equal the traction available. This is noticable going down an ice covered highway. As you get up on the speed, the front tires will begin to actually spin as you reach their traction limit as the wind resistance increases. It's quite safe to drive very fast on a very slippery surface with a fwd car...as long as you don't do anything else like brake or turn.

Now going to a rwd car, the whole thing is a balancing act. Since the drive wheels are behind the center of mass of the car, it behaves almost as if you were doing a circus trick like balancing a long pole on your chin or something. It's naturally unstable and requires constant input to keep balance. In normal driving, it's not a problem because, you're not approaching the traction limits of the tires. However, on low traction surfaces, you will quickly approach the limits. At the limits, the rear end will want to sway side to side essentially trying to turn around and get ahead of the center of mass. It's basically trying to get to a balanced state. The driver's goal is to try to keep the driving force in line with the center of mass to keep the rear end behind you.

In the above sense, fwd has the clear advantage just from stability. However, there's more.

In my opinion, I'd personally prefer a rwd car in a low traction situation, not for stability but rather for control. Rwd has a certain advantage over fwd and awd cars as the front and rear ends can be controlled seperately, the front by steering, the rear by throttle. This is why rwds are very popular for drifting. You have the ability to control what the front and rear tires do, independently. You can control traction and car direction from either the front or rear end. You have a lot of freedom to manipulate the car. As well, a rwd can usually gain a little more traction when getting on the throttle from the weight shifting back during acceleration. A fwd would actually lose some of its traction during acceleration. This is why I'd choose a rwd car. Also, it's quite fun in the winter.

Now for the normal driver, a fwd would still be the choice just because of simplicity and its natural balance by having the drive tires ahead of the mass of the car.


Now on to understeer/oversteer.

Understeer and oversteer can be adjusted into any car, fwd or rwd, through the suspension setup. The only time a fwd and rwd changes is when you get on the throttle. When you do this, the drive tires give up some cornering traction to provide thrust. This is where you can induce understeer or oversteer in a car, and this will be different in a fwd or rwd car.

A fwd car will gain understeer when you get on the throttle. However, it's not quite so simple. Since you can actually pull the car in different directions with the front tires, you can actually make up for some traction loss by driving into the turn. If the supsension was set up properly, you should actually be able to induce oversteer, even with a fwd car.

A rwd car is different. When you get on the throttle, it will begin to oversteer...maybe. You will give up some cornering force to the driving force. However, you're also moving weight to the back of the car. If too much goes back, you could actually still understeer in a corner.

Now I bring up these points for a reason. In my eyes, fwd is not solely associated with understeer and rwd with oversteer. From the factory with its stock suspension, most if not every car is built to understeer some for safety. However, with suspension tweaks, you can pretty much make any car do what you want, up to the point limited by the laws of physics.


So, what's safer?

Well, it's not as simple as fwd or rwd or oversteer or understeer. It still comes down to the driver. The normal person with little experience with pushing their cars will be safest running a fwd, understeering car. It's naturally the safest and easiest to control when pushed hard. However, moving to the opposite end with an individual that can actually control a car quite well at its limits, he or she may actually prefer a rwd car that is neutral or may even have a little oversteer(maybe not, lol, maybe a hair understeer actually to allow throttle oversteer). A person who can control a car in such a manner may feel safer and could benifit from the ability to further control their car.


All in all, there's really no clear answer. It all kind of depends on the driver and their preferences. In the general, whole society term, as well as in a pure physics sense, a fwd with understeer would provide a good racing platform as well as good stability. It's not the fastest and you may not have the most freedom of control, but it's a good setup to work on. I personally would be extatic with a rwd car with a hair amount of understeer than can be turned to oversteer by both brake and throttle inputs. That's just me.

[AuspeX]

Originally posted by Drift For Food
For motorsports applications, especially low traction, I'd personally choose a fwd car.
...
In my opinion, I'd personally prefer a rwd car in a low traction situation

You can actually achieve faster speeds in a fwd than with a rwd
...
a fwd with understeer would provide a good racing platform as well as good stability. It's not the fastest...

I read your post and found it quite interesting. I just thought it was funny that you contradicted yourself... twice. :P

[UberSpeed]

*EDIT* o snap my bad. Didnt really think just got a lil cocky. Sry about that
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Anyvayz, FF is generally better in poor/rally conditions for the said reasons. Most of the weight is over the drive wheels, giving it better traction, and all of dat. But on to my theory-

In most all rally races, people drift through the turns to keep their momentum. In a FR car, you have to be very carefull on the throttle so you do not spin out or create too much of an angle that will have to be corrected, thus losing speed. This is because of the said balancing act that occurs. It would be damn near impossible to put your foot on the floor and "explode" out of a corner on a RWD car without flying off the road. In an FF car, you can mash the throttle and theoretically pull yourself out of the corner/slide, and you dont have to worry about spinning out, thus giving you higher exit speeds. Just my 2 cents

[NeveR]

Hey UberSpeed take a wild guess as to who he's talking about in his first post.

I'll give you one hint: Me.

[Drift For Food]

Yeah, a bit of contradiction, but I stand by it, lol. For motorsports and during a time when you are constantly at the edge of the car's capability, I would prefer to be in a fwd, especially when being competative. It's an easier system to work with.

However, if I had the choice, I'd go with a rwd platform for control and the aditional freedom. In a competative environment, this may not be the optimum choice as it can be a bit more tricky to push hard consistantly without mistakes. However, despite some loss of ease, I'd still choose it short of if I had to be compeditive with it. It's more of a "fun" platform for me than a pure racing platform. A simularity would be me chosing an automatic transmission or sequencial clutchless over manual if it allowed me to concentrate on my driving more by simplifying what I have to do. It's why you see WRC cars lose a lot of time if the drivers are forced to use the manual back up. It takes more work and isn't as efficient. There still is some trade-off with control.

It's all balance and trade-offs. For motorsports, you need to concentrate on what's needed. All the little things that would distract you from doing your best should be elimitated. But, if you don't need that much focus and concentration, you can afford to add controlability and freedom of a rwd and a manual transmission since you have a little more room to play. It's that little difference between what you want and what you need to gain an advantage in a motorsports situation.

[Drift For Food]

Oh, the fwd thing.

Yeah, if you've ever had the pleasure of driving a fwd and rwd on ice, you'll quickly realize that a rwd becomes unstable at a lower speed than a fwd car. Unless you can perfect balance the rear tires beind the center of mass of the car, you can't keep speeding up without having the rear end getting squirrely. This is top speed, not necessarily lap times. It's a big general too and one car being faster than another is also very dependent on the cars you're comparing and how they're set up. Both fwd and rwd can be very fast when tuned right. In theory, one would conclude that a rwd would be faster simply because you don't gain the effect of understeer when trying to both turn and accelerate. The rwd has the advantage of seperating the tasks and should be faster around a corner if the cars are of comparable specs.

It's tough to compare such things since there are so many factors behind this.

I was also suggesting a fwd with understeer would be a very stable racing platform, but it won't be the fastest as it may not be optimally balanced for the track it's on. A fwd has a hard time overcoming understeer. All it can do is slow down. As well, understeer indicates that the rear tires have more traction that could be squeezed out for increased performance. A rwd can overcome the same problem both through braking like a fwd and from additional throttle which helps with speed. An understeering rwd car can be run harder with more throttle.
Essentially, you'll take advantage of the extra rear traction available by increasing throttle. A fwd can't do this.

[Buddyworm]

I'd prefer FR. Mind you, my opinions stem largly from armchair racing and from my experiences driving in lots of snow with both FR and FF cars.

The first thing I'd consider is the traction on the front wheels and how it affects entry speed. The maximum speed at which a car would need to be travelling in order for its front wheels to have the ability to turn the car sufficiently in order to initiate a weight transfer in the rear and slide around a corner plays a large factor.

In FF, the "follow the leader" scenario of arse following nose would be understeer as the result of excessive entry speed. So the car would have to slow down in order for the front wheels to bite and turn the car enough for a weight transfer to the outside.

In FR, the tendancy of the tail to step out readily with some extra throttle and some steering work would be beneficial. This allows for a higher entry speed because the car will not have to slow down as much as an FF in order to get the rear to come around, nor does it have to use a weight transfer to initiate the slide.


Second, exit speed. Now once the FF car is around the corner and set up for the exit it stands to reason that it will be able to accelerate harder without the worry of spinning out like in an FR.

But consider the speed that the FF car would have to shed before entering the corner and the amount of traction the car has at it's front wheels to allow it to accelerate out of the corner. Get on the throttle too hard and you've got a lot of spin, little acceleration and no steering abilities. Too little and you lose speed.

With an FR you'd already be carrying a higher speed into the corner and yes, it would require fine throttle control but once the car is oriented for the exit and coming out of the slide with the front wheels turning straight forward there is less risk of a spinout and you can apply throttle accordingly to accelerate.



There's my bit. Of course I'm no expert so if you've got more experience than I in this kind of situation (shouldn't be too hard ) please feel free to point out any flaws in my theory.

B-Wurm

[UberSpeed]

Just so we're on the same ground here, not all FWD cars understeer, just most of um =). However this is why they are good for rally. You are never really turning the car hard and exellerating at the same time because of the driting involved with rally, so its not really a problem. This is why just about everyone using 2wd car (including the big dogs a citroen, or at least they used to) in rally uses FWD. Not really jesting with anyone just adding/concurring.

And BTW NeveR sry aboot that. Thanks for not uberflamzoring me. My apologies.

[GRiDRaceTech]

Screw the first question, I don't care.

As per your second: Most race drivers prefer just a tad bit of understeer. It creates a slight buffer zone and thus is less tiring to drive on the limit.

[UberSpeed]

In response to B-Wurm, heres another intriguing question-Entry Speed or Exit speed? Seeing as how our posts kind of contradict eachother, this would be interesting to find out. And by Entry or Exit speed I mean if one has to be higher than the other which should be higher.

[SidewaysGts]

I never said i was talking rally in specific, i said low traction conditiosn like rally racing, snow, mud etc and listed a bunch of low traction situations.

One thing to keep in mind- even FF will oversteer greatly (without the hand brake even!) in low traction situations. The ability to rotate a car despite its drivetrain in the dirt mud snow or whatever is a LOT different compared to paved roads.

The difference comes from the weight of the vehicle being pushed or pulled while sliding, and the speeds atainable (slower in just about all respects, so weight doesnt have as much of a chance to pivot backwards)