This is very misleading and could be easily described as plain wrong. A front engined, front drive car is more likely to plough through a corner because more of its weight at one end of the car, but in a rwd car the prop, diff and half-shafts aren’t so heavy as to make so much difference.
The distribution of any front-engined car is going to be front-heavy - which is desirable in a car for directional stability - no matter where the power is fed to. Whether or not a car understeers or oversteers in the situation you describe is controlled by the design and configuration of the suspension and tyres and the way the power is delivered. It would be a truly evil car which snapped into oversteer if you slowed through a corner. One with the engine cantilevered out beyond the rear axle. But one which can develop the ultimate car-driver respect. The human mind enjoys adapting itself to something odd but predictable, if the results are good. So there are some gorgeous Porsches but the always-unpleasant VW Beetle.
Possibly you have confused rear wheel drive with rear engine, Airman Doors?
The point of front drive is that it gives better traction in slippery conditions, reduces the weight of a vehicle, eliminates the need for a front-to-rear propshaft and will not turn evil if a novice driver applies too much torque to the driven wheels through a wet corner. Using mechanics, it is actually pulling the car in the direction the wheels are pointed in, not pushing it straight on and acting against the wishes of the front end in a corner. It makes huge sense.
Advantages of rear drive are that it removes the corrupting influences of power through the front wheels, allows a car to be more easily adjusted in its attitude through a corner by using altering the side-slip of the rear tyres and permits a powerful car to be easily swung round in its own length, from low speed, by spinning the wheels to make a rapid exit in the opposite direction amidst a cloud of smoke. Good if you are presented with a gunman looking to hijack your occupant(s).
Missed the 5 min deadline - meant to add this:
But if rear drive is so much better on winding roads, why did the Nazis ditch their hugely-powerful Mercedes-Benz for 60hp Citroëns when they occupied France? They couldn’t keep up with, let alone catch, La Résistance who drove these iconic - and front drive - machines.
Well, you seem to have attempted to post a picture in your post, which we don’t allow on these boards. Why it came out looking like that, I don’t know.
Difficult to say with certainty, but ISTR that a right-angle hypoid or spiral gear drive is typically about 90% efficient, whereas a simple coplanar spur/helical gear is more like 97-98% efficient. Maybe someone else reading this thread has more definite numbers?
Can someone explain in easier to understand terms why FWD tends to understeer while RWD tends to oversteer? And also why torque steer (which, by my understanding, would create oversteer) doesn’t counteract the understeer of FWD?
As pointed out above, it isn’t as simple as FWD=understeer, RWD=oversteer, the setup of the suspension and car as a whole controls the balance, but the trivial idea of the difference is simple.
Go into a corner reasonably hard, so that the car is approaching the limits of adhesion. Now use the accelerator to break adhesion of the driven wheels (ie either lift off, or plant your foot, enough that the driven tyres lose their grip.) Now which way will the car go? Clearly a car losing adhesion at the front in a corner will tend to rotate out of the corner and thus understeers, whilst a car losing adhesion at the rear will tend to rotate into the corner, and thus oversteers. That is it. In a specific circumstance you get these tendencies. But if you don’t use the accelerator to break adhesion, and rather simply overcook the corner, or otherwise lose it, it is up to the balance and setup of the car as to which way the car goes. Further, it is possible to make any car break out at either end with enough skill, mostly down to steering input as you go into the corner.
Torque steer doesn’t apply once you lose traction. It is a problem in that the two front wheels are not driven identically, but are driven via a differential. Torque goes preferentially to the driven wheel, and that wheel tends to pull the car around, and thus steer the car. Better FWD cars attempt to ameliorate this with active torque splitting control, limited slip differentials, or the like. A mate of mine had a Honda Prelude that did this - it was pretty effective. However, torque steer is always the same direction, so the effect is different going into left versus right handed corners. That isn’t good.
I watched a BTCC race on TV last night. All these cars have nearly identical power. Most are FWD but there are a few RWD BMWs. In the dry races with slicks they could all launch without wheel spin and neither type had an advantage. But in the wet race the BMWs got off the line far better due to better traction.
In this week’s Top Gear they tested 3 different FWD hot hatches and Hammond was able to get all of them to oversteer while hooning around the track.