ANGLING AROUND
Mr. Ehrenberg–
I recently took my 1973 Plymouth Fury III
in for a front end alignment. I brought him
some of the specs you recommended,
and a Xerox copy of the factory manual
specification page. It shows something
called “Toe out on turns,” which was
specified as “Inner wheel is at 20°, Outer
wheel is at 18.8°”, I showed this to the
fellow and he just shrugged. And older
guy in the shop said “that’s Ackerman,
we don’t check that, there’s nothing to
adjust.” I certainly have no idea, so I am
asking the Indian chief, Dr. Ehrenberg, SAE.
The car drives fine, by the way.
Ol’ Rudy Ackermann (two n’s) was a Brit
who patented what
I’m about to describe in Britain
in 1818. He usually gets credit
for the design, but he was just
the patent attorney, Georg
Lankensperger from Munich
(think: Beer Hall putsch) was
the inventor.
If you think about your car
making a tight turn, the inside
wheel is quite a bit closer to
the center-point (of said turn)
than the outer, so that wheel
must turn more sharply. Turn
the wheel all the way to the
stops, then check the turn
angle of the inner wheel vs.
the outer. You can usually see
Ackermann at work, visually,
with no measurements. See
drawing,
The reason this is spec’d in the book,
even though no adjustment is possible, is
to help you diagnose steering problems,
usually after a crash has deviated some
steering, suspension, or chassis/frame
parts that have been supposedly repaired
or replaced. Or need to be.
