This is what Ford calls the ride-height...
...they won't say what's "best" they just give a range.
But in the '75 Shop Manual they do say to place blocks between the frame
and axle to bring the ride height up to 4" before taking alignment readings if
the ride height is less than 4".
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Read lots of places what-they-thought caused front tire cupping. For me and
my old clunker the main problem was too much toe-in! For some dangged
reason every time the "alignment guys" adjust the toe-in, they go for -more-
rather than -less-.
From my experiments I've found that I like the way almost-zero toe-in feels
while driving and I've reduced the front tire cupping on an older twin-I-beam
to almost none too. Heard many alignments guys say "it's a Ford thing" and
leave it at that when asked about front tire cupping.
Zero to 1/32" toe-in is my favorite...
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~1/8" toe -out- in the -front- was my favorite for VW based dune buggies.
Big sloppy tires would let the dune buggy lean and the front end would grip
better, from more weight on it, and then steer it more than you wanted.
So you'd rock back and forth with toe-in.
As straight as I could get the -rear- (all measurements with weight in 'em!)
worked best for both dune buggies and Bugs.
Straight as you can get 'em works best for motorcycles and bicycles too!
Alvin in AZ (is rattling on about crazy-shit again)