Toby
Thanks for your comments.
I didn't realize that the A-arm bushes were copies if a Brit design, but should
have figured. Well there certainly will be no rational reason for the use of
this system.
On the subject of steering angle, Ackerman formulated the description of
arrangement of the steered wheels so the inside and outside wheel angles
matched the respective turning radius, as you have stated. His description was
made before the advent of weight transfer and scrub angles (slip angles). As
we toss our sports through the corners, the outside tire sees loading due to
transfer of weight, and so run at a greater scrub angle than the inner tire
which is lightly loaded. Thus Anti-Ackerman is called for.
I had done a bump steer analysis back in the late seventies and found the
values pretty good. I am but I have not kept the numbers.
Regards
Calvin Grandy
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> From: Toby B <toby@wolfenet.com>
> To: a roadster list <datsun-roadsters@autox.team.net>
> Subject: Re: front end geometry
> Calvin Grandy wrote:
>
> > Inspection has shown that the wishbones of the front suspension
>are "swept back" about 10 degrees from perpendicular to the direction of
>travel. what does this geometry contribute to handling or cornering
>stability / power? Is it just an assembly of parts, or is there a method?
>
> If you re-eyeball it, you'll find that the trailing a-arm pivot lines up
> with the ball joints. As to method, ? It does make the front
> suspension into a slight trailing arm, doesn't it?
>
> > Has anyone modified the front steering system to provide anti-Ackerman
>geometry as is consistent with present day tire performance?
>
> The stock design does have Ackerman-angle compensation built in.
> Hmmm... if the slip angle goes up on both tires (theory being that
> modern tires have greater operating slip angles) would that change the
> Ackerman angle much? Wouldn't seem to...
> (Ackerman angle is the technical term for "inside tire has to turn into
> a corner more as it's radius around the turning point is smaller than
> that of the outside tire')
>
>
> Hmmm, again, on a similar topic- how much bump-steer is built into the
> stock suspension?
>
> Toby
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