Thanks Guys , what a good read.
I think I have followed the argument but feel free to correct me.
On a race set up we use a fairy high number for -ve camber and stiffer
springs.
This gives us a much lesser (slip angle?) I mean the outside tire is far
more upright during heavy conrnering.
however straight line breaking does suffer a little as there is more force
on the inside of the tire. In the wet there is less body roll so the -ve
camber is less effective (with High -ve camber).
The importance seems to be with the outside tire for circuit racing as if I
slightly error on the apex and take in a little of the ripple strip with
the inside front wheel , it has very little effect on the attitude of the
car. (We dont have any banked tracks).
The ackerman angle seems only to have importance in the inception of the
turn (less so if you are under brakes and turning) and perhaps the late
part of the exit as it is in thse spots that both frnt wheels are doing a
lot. In the rest of the turn it is the job of the outside tire. Most
racing schools seem to emphasise that effect in looking at steering under
breaking.
Regards,
Howard
-----Original Message-----
From: Toby B [SMTP:toby@wolfenet.com]
Sent: Saturday, 6 November 1999 8:31
To: a roadster list
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?
> Is the small change in A-arm location associated with suspension
deflection part of some design, or are the threaded "end bearings" just a
useful way of distributing axial loads on the A-arm spindles?
It's a brilliant copy of a wacked British design on the TR4. The slight
movement fore and aft is way too small to make any handling difference.
One benefit, tho, besides having your a-arm pivots wear out in 500 miles
if you don't grease them, is that it's a really low-defelction design-
those metal bushings have zero compressability!
> 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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