Originally posted by forcedinduction
You say that neither one is entirely bad, but you make it sound like that one would prefer more a more positive caster angle than a negative one, correct? Also, at what point does too much positive caster hurt a FWD car? I've seen most FWD cars to have a stock spec of about +2-2.5* while other RWD cars like the 240SX and Porsche 914 are blessed with as much as +6-7*!
Ok, neither is really preferred over the other, besides the weight transfer advantage, caster helps to return the steering wheel to center naturally when you exit a corner. No matter whether the caster is positive or negative, there will still be a tendency for the steering to return to center, although probably marginally moreso with positive caster.
Now, the reason for so much rear caster on a rear wheel drive is because the chassis can use it more. The power is delivered at the rear wheels, so the more cross weight you can get to the wheel, the harder you're going to force the tire to work in your favor. Obviously this has some limits, but that's the basic principle. On a FWD car, obviously the power is not delivered at the rear wheels, so you really only need to get enough weight transfer to keep the rear of the car predictable. It's all about weight transfer and cross-weights for corner entry.