minimizing scrub, high KPI or lots of BS?

[boodlefoof]

Hi guys,

I'm getting ready to tear back into my Datsun 240-Z project. I'll soon be buying a suspension design program to help me figure things out, and then I'll begin the front snout of the spaceframe.

Been reading over material on scrub radius and have a question. I searched the archives and didn't find anything about this.

I may be missing something obvious or my suspension theory may not be 100%, so let me make sure I know what I'm talking about first off... Scrub is the distance at the ground between the wheel centerline and the intersect point of the imaginary line running between the two ball joints yes?

So, most people solve the problem by using a steeper KPI (Herb Adams' book recommends 7-9*) to make the imaginary ball joint line more angular... thereby making the intersect closer to the wheel centerline.

That is fine, but what I don't see people doing is using a spindle with 0* KPI and just moving the steering knuckle further into the wheel. With today's larger diameter (and wider) wheels, it seems like this would accomplish the same thing. If you have a short BJ to mounting surface length, (say 4'') you could use a 10'' rim and have the ball joint centerline directly in line with the wheel centerline.

Maybe this just isn't practical, but is there any other reason not to do it this way (aside from space considerations inside the wheel)?

Thanks for any comments. At present, I'm planning to probably go with C5 front knuckles and will build the control arms around that.