about kingpin

[Greg Locock]

KPI primarily affects the steering wheel jerking in response to bumps, it's more of a subjective annoyance than an objective one.

FactsOnly - the points system is there to comment on the accuracy of posts, it is not a popularity contest.

[peaty]

Like Greg says, if you put the camber adjustment outboard of the upper and lower ball joints then the camber can be adjusted independent of the KPI.

Typically this is done by using shims between the upright body and the ball joint clevis like these implementations:
https://www.formulastudent.de/uploads/R ... 10.png.png
http://poisson.me.dal.ca/~dp_10_14/olda ... es/ups.bmp
https://scarbsf1.files.wordpress.com/20 ... 1_susp.jpg

This way your kinematics remain untouched because all the joints stay in the same position.

If you do the camber adjustment by adjusting the inboard or outboard joints on the control arm you change not only the camber and kpi but also the camber gain, scrub radius, motion ratio and roll centre height as well the rate at which all of these things move with wheel travel. In my opinion its a pretty crappy way to change the camber on a race car (albeit a very commonly used method).

Another thing, when I change caster by changing the relative length of inner BJ, Am I changing kingpin as well and therefore other parameters (camber gain, scrub radius...)!?
How do you change caster in the caterham suspension!?

[Greg Locock]

see http://www.caterham-build.co.uk/article ... roper.html, no that won't affect the KPI or scrub or camber gain, it will affect the ackerman, although probably not enough to notice.

It is more usual if you have an upper wishbone to alter the caster by moving the front inner ball joint out, and the rear one in, , or by moving both backwards. The latter is a bit neater. The reason you do that to the upper arm not the lower is that hopefully the lower arm is built in with minimal compliance, as it takes most of the load, so you don't want to stuff with it.

[peaty]

so, now moving on into camber (camber gain and camber compensation), how much is enough!? I know we want the tire with a bit of negative camber when we are cornering but by doing this we might hurt other things (excesive tire wear perhaps? or, as Tim.Wright said, smaller contact patch when the car squats). So where is (or where should be) the line!? how much effect has tire width into this!?