ttAmerica RoadsterAWD

Steering axis inclination (AKA King Pin Inclination) is the angle measurement between true vertical line drawn thru middle of the front tire and the center of the strut, with the vertex at the intersection of both on the tire floor surface.

If you have monoball setup with adjustment capability, what is an ideal measurement of this?

I'm researching alignment specs for my car before I go to the dealer. I"ve never heard of this measurement, but now I see how I can move this setting on my monoball JIC/Cross.

Any thoughts??

ValveFloat

I may get corrected here, but your SAI will change when you change your camber at the camber plate. To some degree the camber can be changed without changing the SAI by adjusting at the strut-knuckle mounting location, but mostly you will adjust for the camber you want (at the camber plates) and "live" with the resulting SAI.

ttAmerica RoadsterAWD

Thanks, makes sense. So, is it "usual" to align camber plate to zero, then align top strut eccentric to zero (to coincide), and then only move the camber plate to desired camber? Seems this is the way it should be?

anybody?

joey bagadonuts

I think it's the opposite. Based on how it's measured, SAI will change with adjustments at the knuckle. Moving the strut via the camber plate will only affect camber--the SAI will remain fixed.


From what I read, it seems that SAI, Included Angle and Scrub Radius are used to determine if your chassis is bent.

ValveFloat

Yep, I should have thought about it more before posting.
I found a similar diagram and played with it a bit.
Because the bottom of the tire moves out as negative camber is added, changing the camber at the strut top has less or no effect on the scrub radius. The SAI changes, but scrub radius doesn't.
Adding negative camber at the knuckle-strut joint doesn't change the SAI, but still pushes the bottom of the tire out, effecting scrub radius.

This is all based on a simple diagram though, so reality may differ.

joey bagadonuts

Okay, that makes sense. I think you've got it.