Howdy,
On Wed, 28 Apr 1999, Scott R Sawyer wrote:
> I have a question about the alignment on a front drive car. Almost
> everything I've read and heard has recommended running toe out in the
> front. In a few places though, I've have seen toe in recommended
> (Grassroots, June/July '98). It seems to me that running toe in would
> work better because as you start to turn into the corner you load the
> outside tire. Since this tire is turned in more than the amount of
> steering lock you have cranked in (because it was preloaded from the
> toe), I would think the car would turn in more quickly. Is this right? If
> not, why? Basically, I'm just trying to get an idea of not just WHAT
> works, but also WHY. TIA.
Please bear in mind that what follows is nothing but what I think, and
most people would call me an idiot. In fact, a lot of people have
already... :-)
In my mind the major thing toe (in or out) does in a car with decent
Ackerman geometry stuff is to preload the suspension bushings. On my neon
(which supposedly has good Ackerman geometry stuff), let's do a little
mind experience with a right hand corner:
With toe out, the left front tire has compressed the suspension bushings
so that rotating the tire clockwise (to make the righthander) will
instantly transfer that force to the chassis.
With toe in, the left front tire has compressed the suspension bushings
the _other_ way, meaning that rotating the tire clockwise will first
unload the suspension bushings, then load the suspension bushings, then
put the force into the chassis.
I think that's why people seem to like toe out and its why I run some
(3/16" in my case). Everyone says it makes the car turn in better and I
think this is why.
Now in a mid corner situation what I've heard gets a lot more muddy. The
only thing you can guarantee is that you want the inside tire to be on a
different radius (ie. turned more) than the outside tire. I've heard
people say that toe out takes care of this, but I don't buy it for every
car. That Ackerman geometry stuff that I barely understand accounts for
this. Just like how if you change your camber your toe changes, as your
suspension travels through its range the wheel turns a bit. Whether or
not your car (or really mine for that matter) turns the wheels the right
amount for a given corner radius, I don't have the foggiest idea. I have
heard people, mostly roadracers, say that adding toe out to a neon makes
the car understeer in the middle of a corner. However, I haven't heard
them back it up with data.
So in short I think that running toe out doesn't do anything more than
preload the bushings so that steering response is more immediate, but I
haven't ever run measurements to verify that's the only affect.
Muddy enough? :-)
Mark
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