Cal Club Autocross Forums

http://www.davidfarmerstuff.com/Toe-Ackerman.pdf" onclick="window.open(this.href);return false;

Thanks, Mako! Perfect insomniac reading

Hmmmm... I was under the impression that an approximation to Ackerman steering had been implemented on cars (and buggies) by clever placement of tie rod ends since the early 1800's. For high speed, large radius turns like ours, Ackerman effects are small and the weight transfer (and resulting change in slip angle at maximum lateral acceleration) have a large effect on the optimal steering angles. I suspect there may be more to the toe-out story.

sc

For high speed, large radius turns like ours

hmmm ... I though our AX corners were tight and low speed for the most part

"First, you need to know about Ackerman."

Then you need to know about slip angle -- apparently he doesn't.

Steve Collins wrote:Hmmmm... I was under the impression that an approximation to Ackerman steering had been implemented on cars (and buggies) by clever placement of tie rod ends since the early 1800's. For high speed, large radius turns like ours, Ackerman effects are small and the weight transfer (and resulting change in slip angle at maximum lateral acceleration) have a large effect on the optimal steering angles. I suspect there may be more to the toe-out story.

sc

You are correct, steve. Chrysler built it into their designs since the fifties, and I've never bothered to look back farther than that. I'm suspect of this source.

Mako Koiwai wrote:

For high speed, large radius turns like ours

hmmm ... I though our AX corners were tight and low speed for the most part

Compared to road course, yes. But in this context, what matters is the turn radius relative to the wheelbase of the car. "Small radius" turns here would be something that requires large steering angles, like parallel parking. If cars didn''t have close to Ackerman steering geometry, you'd get hellacious tire scrub when parking. The picture on the guy's web site is what I'm calling a "small radius" turn.

sc

that is a great article, the only thing I think can be improved on is at the bottom he says he likes 1/8" max, more like 1/16th. well then problem with that is 1/4" on my 13's is WAY different then 1/4" on homeboys 22's"... ok more realistic in racing, your 18's.

your average home brew toe alignment is done by measuring from the lip of the wheel, to the lip of the wheel.... etc (if your reading this, I'm sure you know how to check toe).

a much better measument is in degrees. 2 degrees is 2 degrees no matter what size rim.

I once found a chart and equassion to figure out your degrees if you know your rim size and measument, and vise versa. I cant seem to find it right now though.


20 minutes late: here it is.
http://www.smartracingproducts.com/pdfd ... ttings.pdf" onclick="window.open(this.href);return false;


EDIT: OMG. i see this was JUST talked about in anothr thread here. My bad.
viewtopic.php?f=6&t=4893" onclick="window.open(this.href);return false;