No problem -- I appreciate the comment. I don't want to be in a monologue either and sorry for the late response. First, do you have to use such a scary word, "wayward"? How about "alive"?
>>>>>
This would mean that there are no good arguments at all for front-wheel toe-out.
>>>>>>>
No question that there ARE negative trade-offs, but I am not sure I would agree with the above statement. I did not plug the idea of front toe-out promoting steering response out of thin air; its usage comes from (at least) a couple of the most trusted names in Porsche suspension set-up in Southern California; one sets up my car, the other sets up a friend's Turbo on 6speedonline. I continue to suspect also that this is the one used by Alex's first tuner, PAR of England.
As in all suspension decisions, there are trade-off's (straightline stability, twitchiness), so this much I would agree: a. that this setup is NOT for everyone or very situation, and b. some would argue it's more for a track car then a street car. (OTOH from my experience so far, it is A LOT LESS twitchy or "un-directional" than I had expected. I thought the thing was going to wander all over the freeway; this is not the case at all, at least as set up in my car.)
As for explanation, I would agree that without a professional here, it would be dangerous for me to speculate on an explanation. That said... why not? It's fun, and sort of harmless. You seem to be concentrating on the outer wheel -- and your explanation makes sense to me, but... the articles that I have seen appear to concentrate on the inner wheel. So clearly there are 2 opposing effects, inner wheel effect causing the described quicker turn-in response, that much I would venture.
Besides what was said by my tuner, I have run across several articles expressing the same idea. There is no unexpected "exception" to the rule that I have seen. Here are 2 that I like - sorry I have no access to authoritative textbook:
http://www.ozebiz.com.au/racetech/theory/align.html
....If the car is set up with toe-out,
however, the front wheels are aligned so that slight disturbances cause the wheel pair to
assume rolling directions that do describe a turn. Any minute steering angle beyond the
perfectly centered position will cause the inner wheel to steer in a tighter turn radius
than the outer wheel. Thus, the car will always be trying to enter a turn, rather than
maintaining a straight line of travel. So it's clear that toe-out encourages the
initiation of a turn, while toe-in discourages it.
....The toe setting on a particular car
becomes a tradeoff between the straight-line stability afforded by toe-in and the quick
steering response promoted by toe-out. Nobody wants their street car to constantly wander
over tar strips-the never-ending steering corrections required would drive anyone batty.
But racers are willing to sacrifice a bit of stability on the straightaway for a sharper
turn-in to the corners. So street cars are generally set up with toe-in, while race cars
are often set up with toe-out.
http://www.mgf.ultimatemg.com/group2/suspension/toe.htm
...If the car is set up with toe-out, however, the front wheels are aligned so that slight
disturbances cause the wheel pair to assume rolling directions that do describe a turn.
Any minute steering angle beyond the perfectly centered position will cause the inner
wheel to steer in a tighter turn radius than the outer wheel. Thus, the car will always be
trying to enter a turn, rather than maintaining a straight line of travel. So it's clear
that toe-out encourages the initiation of a turn, while toe-in discourages it.
Finally, phew, there is actually an active thread where a couple of people mentioning the front toe-out setting of their cars on rennlist. If you still have questions about how it could work, I think that would be a good place to post the question. Those guys are a little nutty but to me are very knowledgeable & experienced: http://forums.rennlist.com/rennforums/997-gt2-gt3-forum/472590-my-gt3-handles-like-a-truck.html
fritz:
....
I cannot claim specialist knowledge of setting up suspensions but I would expect toe-out to be not just "twitchy" but positively wayward, and far from improving turn-in response I would expect it it to delay the building up of steering force in the outer front wheel when initiating a turn, resulting in poorer response.
This would mean that there are no good arguments at all for front-wheel toe-out.
....
--
Regards,
Can
997 Turbo + Bilstein PSS10 (Review) + Cargraphic Exhaust (Heavenly Race Car Noise Review)