Ken Landaiche wrote:
>This weekend I was looking through Carroll Smith's books and came
>across a passage where he described making the front wheels toe out in
>bump, in order to dial in more Ackerman angle while leaning in a curve.
>I had never considered having toe adjustment change for different parts
>of a wheel's travel. Do road cars have these sorts of complex
>interactions, or is for instance toe in/out supposed to be constant
>through the whole travel of the wheel?
Road cars generally have more designed-in imprecision (rubber bushings for
isolation, more flexible chassis, softer sidewall tires, softer springs) and
it's a good thing because the typical road has much more "character" to it (pot
holes, dips, varying camber within a turn, rocks) than the typical race track or
slalom course.
So it's more tolerable for a street car's suspension to be less than perfectly
adjusted and controlled. Also, the rubber in the system (among other things)
makes it probable that a perfectly aligned suspension won't return to the same
data points consistently.
Nevertheless, if you make the attempt to get a nice, nominal alignment, you'll
be within the right range and the car will feel much better than if the
adjustments were random (not as unusual a situation as it may seem).
Somebody mentioned a bump steer adjustment where some toe-out as the suspension
is in compression is desirable to avoid toe-in as a response to a little rise in
the road during cornering.
I hadn't thought of this but it makes a lot of sense to me. The last thing I
would want in the middle of the turn is a sudden understeer (which you're likely
to get if the outside front wheel toes in more in response to a bump).
But then, these situations happen all the time and if the driver is aware of the
possibility, he can also be ready to momentarily open up the steering a bit to
compensate. It's just more relaxing if he doesn't have to do this constantly.
Rod
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