On Sun, 9 Jul 2017 13:03:26 +0000 (UTC), Chaya Eve
wrote:

On Sun, 9 Jul 2017 19:56:29 +1000, Xeno wrote:

The car steering geometry specs will have been designed to make your car
safe to drive in all circumstances.

The specs are almost always a *range* so there's room to be at one end or
the other, isn't there?
There is a range that is acceptable, but a car can be "within spec"
in EVERY measurement and still handle like a cow on skates, wear tires
like a bugger, and generally be a handfull on the road. This is why I
said a GOOD alignment tech can tell you if your alignment is a problem
- and a good alignment tech WILL test drive the car both before and
after alignment. There is a certain combination of caster and camber
lead that will give the required stability and steering feel as well
as the best tire wear, and combined with that there is a PROPER amount
of toe-in or toe out that will provide the lowest rolling resistance
and the best tire wear. Knowing that comes with a LOT of experience,
and an excellent understanding of the angles and forces involved.
Sometimes getting the camber or caster lead that is IDEAL is not
possible, so compensating with the other angle can be used to make the
car run straight down the road.
A car will pull to the side of the most negative camber, or the most
positive caster. So if the caster and camber ar within spec but at the
maximum neg cater and pos camber on one side, and reverse on the
other, it will want to do circles around itself going down the road -
as an example.