Roger Mills wrote:
In an earlier contribution to this discussion,
dennis@home wrote:

On modern cars the steering geometry changes by design.
I can't see how the steering rack makes any difference though.
Its controlled by the top and bottom bearings of the hub and the
direction the wheel is facing, not how much rack is hanging out of
each side.

That's not quite true! If the links from the ends of the rack to the
steering arms on the hubs are of unequal length, there is a strong
likelihood of bump steer. When correcty adusted, those links should shadow
the wishbones - allowing the wheel the move up and down without steering.
But if you make one too long and the other too short, that no longer
applies.
Yuyp. I bought a second hand XJS that had been in a smash..and fixed.
Well I drove it for two years through to its SECOND MOT after I bought
it before they discovered that the actual kingpin was bent, and this had
been taken out with extremely offset track rods and a few other
adjustments. A fast corner on an undulating surface had it squirreling
like mad! You get the same with a lot of McPherson strut type suspension
layouts as standard.

When I used to drive Spridgets madly, and Spitfires, I could always tell
when there was any unevenness or play - well below MOT failure levels -
anywhere in the front suspension. You can feel it in a double wishbone
system. McPerson's you cant, because they are basically crap
anyway..there is more wheel lateral movement from bump steer and it
totally swamps the variable tie rod issues.