On Tue, 10 Dec 2002, James Creasy wrote:
> > ABS allows you to brake to the ability of the tire with
> > the BEST traction instead of braking to the ability of the tire with the
> > WORST traction.
>
> unfortunately this exact behavior tends to create understeer because it
> releases the brakes differentially: that is, it reduces the brakes only on
> the inside front losing traction, not all four brakes like a driver does at
> threshold. the outside tire has more traction, and creates a moment arm
> from the center of gravity around that side (the outside) with greater
> traction, i.e. understeer. i noticed this in stuart langager's miata, the
> only r tire ABS equipped car ive driven recently.
My experience is that it creates much less understeer than without ABS,
when the inside wheel instead locks and goes into sliding friction, where
it assists in turning not at all and braking only very little.
A driver doesn't lock "all four brakes" when there is lateral acceleration
happening (which is the scenario I described), unless s/he's hopelessly
hamfooted. You lock the inside wheel(s), which ones depending on the bias
adjustment. The outers may then slide and/or lock because the insides
are no longer doing much work, but at that point you're already screwed.
In distinction, if you're braking to threshold on the outside front of a
decent ABS car, the other channels are allowing those wheels to continue
contributing to the cause, from each according to their means. You have
smoother, harder, more effective braking.
KeS
|