drag on the inside tire on turn-in, which is an oversteer moment.
> For whatever reason, a fair amount of toe-out in front seems to be more
> the rule for road racing. Generally it is said to help the car turn in,
> and on that note remember that in road racing you spend very little time
> in pure cornering, most of the time is spent under diagonal loading -
> decelerating while turning in, accelerating while exiting. So whatever
> you do with the front wheel geometry is going to have much more of an
> affect on turn-in than it will elsewhere in the corner. It does seem
> though, like if you already have Ackerman steering to properly account
> for the turn geometry, then the harder you push the car and the more it
> yaws outward, the less toe you would want, consequently adding some
> static toe-in in front should help. But that's not what people do, and
> in playing around with it in various sims, it does seem that adding some
> toe-out can make a dramatic difference in a car's turn-in behavior. In
> fact, the few times I have tried front toe-in in a setup the results
> have been horrible, the front end just would not bite. The closest I
> can come to an explanation is this: if a tire is lightly loaded
> vertically, it will require more slip angle to generate the same amount
> of side force as a heavily loaded tire (hope I got that right, I don't
> have my reference books handy). In that case the only way to get the
> inside tire to make a useful contribution to turn-in is to turn it more
> into the corner, i.e. use toe out. The fact that it may compromise
> ultimate cornering power is somewhat irrelevant because you spend
> relatively little time in pure cornering.
> Not 100% sure that makes sense, but that's the best I can do right now.
> ;o)
> > Hello car physicists!
> > I have question about optimum steering geometry for maximum lateral
> > force in steady state cornering.
> > My question is about the inner forward wheel and what our steering
> > angle of that should be.
> > On heavy cornering with accelerations, like g > 1, we will, on most
> > cars I guess, have quite a bit of load transfer which I presume would
> > give the outer wheels the most to say about slip angles, lateral force
> > etc. The total cornering is of course the sum of inner wheels and the
> > outer wheels. Anyhow, what I'm aiming at, is that the outer wheels
> > should prety much go at the required slip angles for the required
> > lateral acceleration.
> > This leaves the inner wheels going att the established vehichle
> > attitude plus, for the front, what steering angle we _happen_ to
> > have.
> > The question is, shouldn't we set up our steering geometry such that
> > the steering angle for the inner wheel is making as much lateral
> > force as possible out of it's situation?
> > For most (all?) tires low load seems to give maximum lateral force to
> be
> > reached at a lower slip angle than with high load - which should then
> > sugest less steering on the inner wheel -> toe in. Is that
> > your conclusion as well?
> > This might be bashing in open doors as everyone seems to be running
> > with toe in anyway (tough the have not told me why).
> > -- Anders Karlsson
