I'm looking at the alignment section in the 1949 100-450 GMC maintenance manual.
The picture with alignment chart is illustrative, not accurate.
Note that king pin inclination is 7-1/6* and camber is 1-1/2*
Added together the kingpin is at an 8.6667* angle with wheel centerline.
Figure a 32" tire, or 16" radius.
Tan 8.6667* X 16" = 2.438" meaning the kingpin centerline at the ground is that much further out than at center of wheel.
I measured best I could front hub and spindle on a 3/4 ton (single wheel) AD axle.
At center of wheel the wheel mounting surface (hub surface) is 3.25" outside of center of kingpin.
Subtract from that the nominal 7/16" inset of stock wheels (is this right?) gives 2-13/16" center of tire tread to kingpin center at center of wheel.
Difference then in the calculated offset due to camber and kingpin inclination and physical offset of hub from kingpin is about 3/8" between center of tire on ground and point it turns on the ground.
Any less offset in wheel or adding wheel spacers increase that offset, more scrub.
So the factory setup is pretty much ideal and good for ease of steering and better steering tire life.
Sorry if that's hard to follow in words. I can make up a drawing if it helps anyone, just ask. (And if I made a mistake it'll become apparent in a drawing)
Grigg
