SAI/Kingpin Inclination mesurement

Hello, I was wondering if anyone has a simple way to measure SAI with a camber gauge? I assume that the angle finder could be placed perpendicular to the camber angle finder, and use the same multipliers as you would use for for castor measurements. I have a smart camber gauge. Thank you.

Hi William, KPI/SAI isn't something I typically measure since it's not something we can adjust or influence unless you're making custom hubs/struts. There's sadly no easy or quick way I'm aware of to measure KPI using something like a camber or camber/castor gauge. What you are going to need to do is to set your hub or brake rotor so that it is truly vertical (0 camber), and then find the angle of the steering axis (for double wishbone that is an imaginary line drawn between the upper and lower balljoints, while for mcpherson strut it's an imaginary line drawn between the centre of the strut top and the lower balljoint. Depending how accurate you're aiming to be this line can be approximated, but for absolute accuracy I'd be inclined to transfer measurements of the balljoint locations onto graph paper and draw everything out so you can accurately measure KPI.

I have seen old camber/caster gauges with an SAI reading. I was hopefull operating perpendicular to the caster plane would be similar or maybe there was a trig app or something. Somehow an alignment machine makes sense of that angle during a castor sweep, but it doesn't seem to be so easy, like you say, to make an SAI measurement manually.