Rear wheel drive - how big a difference?

[Suberman]

Originally Posted by FReSh

It all comes down to the available traction at the tires. A tire can only provide so much grip.

In a cornering situation, a FWD car splits the available traction of the front wheels between turning the car and accelerating. The rear tires only focus on keeping the back of the car from sliding out.

In a RWD car in the same turning situation, the front wheels can focus completely on turning to prevent understeer. Meanwhile, the rear tires split the available traction between turning (holding the back end in) and accelerating.

The question is 'Which is better?'

The answer lies in the weight transfer when power is applied. When a car applies power, it partially unloads the front wheels and transfers that load to the rear wheels. This lowers the peak amount of traction available to the front tires, and raises the peak traction of the rear tires.

In many FWD cars, this causes the front tires to expend all of their traction much earlier than the rears, causing understeer. As a result of this, the rear tires may be "underchallenged" (they have more grip available than what is being used). In this scenario, not all of the available grip is being used.

In a RWD car, the weight transfer under acceleration gives more peak traction to the rear wheels which have to split their traction between turning and accelerating. This allows them to hold the road better than the front tires of a FWD car. This allows for a higher corner speed before traction is broken. The front tires' grip is also used completely for turning (due to increased corner speed and the partial unloading). This allows all 4 of the tires to contribute all of their available traction.

These things give the advantage to a RWD car. It's better to have the turning/acceleration split occur at the tire with the higher total amount of available traction.

The imbalance of traction in a FWD car can be tuned out through suspension adjustments. However, in the best case scenario, no weight is transferred to the rear tires and the front tires maintain their original amount of grip to split between turning and accelerating. This is better than unloading the front tires, but still doesn't perform quite as well as a RWD car using weight transfer to load the rear tires.

Then of course you could add in the torque steer issues and the fact that RWD is more controllable at the limit since you can adjust the car's angle with both the steering and the throttle, rather than just the steering.

RWD wins.

This is not quite true. I don't dispute the essence of what you say but it isn't as straightforward as you may imagine.

For underpowered fwd the front tires can actually utilize some of their traction to pull the front of the car in the direction of the turn. Only if enough torque is available to overwhelm the front tires is this advantage lost.

Secondly, rwd cars use up some front wheel steering grip because the rear driving wheels are pushing the front of the car straight on, the turned front wheels can't use all their grip for turning.

Awd cars always understeer for these two reasons combined: some front wheel steering grip is used up driving the car and some is used to counter the sideways push from the rear driving wheels.

Before modern tires became so good rwd with excess torque could be driven sideways a bit so as to utilize the rear driving force to push the car towards the apex. The ideal line in the 50's and 60's was a good four wheel drift but remember in that drift the front tires are hardly doing any work. The rear tires were using a lot of their grip to, in effect, steer the car round the corner. Modern racing cars do not do this, the rear drive wheels just accelerate the car and the front wheels just steer the car. Modern race cars are much quicker for driving in a slight understeering attitude. Only the are all four tires delivering maximum force to turn and accelerate the car.

[stugray]

Sorry but in my experience, oversteer is easier to compensate for than understeer.

My mid-engined race car would be a nightmare to drive if it had understeer.
The guys I race with all bitch when the "car is pushing".

Schumacher prefers oversteer (he places the car using the throttle)

[chrisl]

Originally Posted by Suberman

Watch F1. No F1 car oversteers unless the driver makes a mistake.

They don't understeer either. Ideally, you want a car to be as neutral as possible, with a very slight tendency to oversteer or understeer depending on driver preference. You definitely don't want a significant amount of either oversteer or understeer though, since it causes you to lose a lot of performance.

[czar07]

You definitely DONT want understeer in an F1 car, or you will go off the track/hit a wall/hit a car, etc.
oversteer you can compensate for by tiny bit of opposite lock, but what do you do for understeer? chuck in more throttle, which will unload the front wheels = less grip up front = more understeer?

[Steve]

Originally Posted by drewbot

This will be my first winter in RWD.

Previously driven FWD (Civic) and FWD w/4WD activated (CR-V).

So long as you check you ego at the door during winter and have a good set of tires, I think I'll be just fine...

Absolutely. Took the FR-S to and from work everyday last winter, including the two big storms we had in the GTA.

Driving cautiously and having proper tires absolutely outweigh and pretty much negate the RWD winter driving "disadvantage" everyone mentions.

[chrisl]

Originally Posted by czar07

You definitely DONT want understeer in an F1 car, or you will go off the track/hit a wall/hit a car, etc.
oversteer you can compensate for by tiny bit of opposite lock, but what do you do for understeer? chuck in more throttle, which will unload the front wheels = less grip up front = more understeer?

In most rear drive cars, more throttle puts a higher demand on the rear tires, which can break them loose and cause oversteer. Alternatively, if you want to get a better corner entry without inducing oversteer in a car prone to a bit of understeer, you can always try trail braking into the corner to keep more weight on the front tires. You definitely aren't completely screwed - there are things you can do to mitigate understeer to a certain extent. That having been said, it certainly isn't desirable.

[TruRace]

FWD gets better gas mileage... all day every day.

[Braces]

Having lived in Alaska for 20 yrs ... I've learned a few things about driving in the snow.

1. FWD will typically have more traction in the snow as compared to a RWD. Easier to PULL a car through the snow than to PUSH the car through the snow.
2. 4Wheel drive with locking diffs have more traction than AWD cars with open diffs.
3. vehicles with skinny snow tires have more traction than wide snow tires.
4. Nothing helps with ice ... Unless you have studded tires or chains

[Sarlacc]

Originally Posted by Braces

Having lived in Alaska for 20 yrs ... I've learned a few things about driving in the snow.

1. FWD will typically have more traction in the snow as compared to a RWD. Easier to PULL a car through the snow than to PUSH the car through the snow.
2. 4Wheel drive with locking diffs have more traction than AWD cars with open diffs.
3. vehicles with skinny snow tires have more traction than wide snow tires.
4. Nothing helps with ice ... Unless you have studded tires or chains

Having lived in Norway all my (rather long) life, I mostly agree with you... but:
1. This is mostly about weight distribution. A VW beetle with rear engine and RWD is a good car in snow, as long as you just need to go straight uphill. If you need to steer downhill... not so much.
The more weight you have on the drive wheels the more snow are they able to push or pull through. It's that simple.
2. Certainly. Many AWD owners are very surprised they first time they get stuck and discover that one wheel with no traction means full stop.
3. In loose snow, yes. On ice, wider tires can be more grippy.
4. Practised driving skills is the only thing that helps on ice. Studded tires are only slightly better on ice than modern studless winter tires. On snow, in rain and on dry roads studless are better.

I am going into this winter with Nokian Hakkapeliitta R2 studless tires on my GT86. I expect them to perform well enough on both snow and ice.

[2013GTRNate]

To me this post shows why AWD is so superior, lol… Especially systems like the Subaru STi, Mitsubishi Evolution and Nissan GT-R just to name a few.

FWD - Front wheel drive is probably the most economical and safe for MOST drivers but for people that value fun and performance while driving I think that most FWD systems are terrible. Nothing sucks more than having a car push into a corner and dealing with all of that understeer. It feels so unnatural and awkward.

RWD - Is the better of the two between FWD and RWD but if the car is a heavy platform like most these days it too can be unbalanced and awkward with a lot of dull feeling. It can take an immense amount driving skill to overcome this. I remember driving my old 300ZX TT and having a lot of understeer followed by excessive oversteer when driving on a road course or AUTO X. Also properly launching a RWD car without launch control has always been harder for me than it is in a car with AWD. I could consistently cut low 1.6 and high 1.5 60ft times at the drag strip with my old EVOLUTION VIII but with my 300ZX TT it was either bog or tire roast…

AWD - In performance cars is awesome. With all of the new technology in AWD systems it just makes too much sense to have it. That is why I like Subaru so much. After owning a 2004 Mitsubishi Lancer Evolution, 2003 Subaru B4 Blitzen, 1997 Subaru WRX STi and driving them in conditions such as rain, sleet, snow and dry weather conditions for several years I finally understand why so many people grew to love AWD over FWD and RWD. Proof of this is that 2 of my 3 cars are AWD. In fact I am driving a 1997 Subaru STi here in Okinawa, Japan until I leave and I love it too… I almost bought a WRX instead of the BRZ but for DD duties you can't beat the MPGs and with the release of the new WRX looming I didn't want to take that hit on the value of an older outdated platform. If not for those few things I wouldn't have ever considered a BRZ.

Don't get me wrong I love the BRZ's sexy looks and its RWD setup but it is good because it isn't a heavy platform.

-Nate

[Suberman]

Originally Posted by chrisl

They don't understeer either. Ideally, you want a car to be as neutral as possible, with a very slight tendency to oversteer or understeer depending on driver preference. You definitely don't want a significant amount of either oversteer or understeer though, since it causes you to lose a lot of performance.

Absolutely they understeer just watch the onboard camera shots from the driving position. The understeer is obvious.

You are correct that you want all four tires working at optimum but "neutral" handling doesn't exist. The more powerful the engine the more understeer has to be dialled in to make best use of all four tires.

For the road you want understeer so that you can throw the car into a corner knowing you have options if the corner turns out to be different than you expected, something completely different from track driving requirements.

Good track cars rarely make good road cars for this and other reasons.

[Suberman]

Originally Posted by czar07

You definitely DONT want understeer in an F1 car, or you will go off the track/hit a wall/hit a car, etc.
oversteer you can compensate for by tiny bit of opposite lock, but what do you do for understeer? chuck in more throttle, which will unload the front wheels = less grip up front = more understeer?

The only opposite lock you'll see in a modern F1 race is when a driver makes a mistake.

You compensate for understeer by backing out of the throttle a bit, a completely natural thing to do. Understeer allows you to push the car beyond the limits and recover. A throttle lift transfers weight forwards, decreases rear traction and allows an overcooked entry to be salvaged provided you haven't really overdone it.

There's nothing you can do about oversteer, you're going off.

A very common misconception is that oversteer can be "corrected" by a "dab of oppo". This is correct only if you are not already at the limits of the car's grip. Idiot journalists and marketing men obsessed with Nurburgring lap times have created an entirely incorrect illusion about what makes a fast car.

And just BTW, it doesn't matter which end of the car hits the wall first, you're still out.

[Speedy000]

driver skill > rwd/fwd/awd
a poor driver will fail with any of the 3.