With real rack & pinion steering the overall steering ratio (ratio of
"degrees of turn at steering wheel" to "degrees of average front wheel
steer") is primarily a function of the "rack factor" (or "C-factor") AND
the geometry of the front upright (hub).
The rack factor is set by the pinion gear pitch diameter in the rack,
measured in inches (or cm) per steering wheel rotation. "Leverage" out at
the front hub is set by the distance from the steering axis to the outer
steering ball joint, (also called "steering-arm length").
Passenger cars wind up around 16:1, F1 cars are quicker, perhaps
6:1, but I don't actually know the range. I'm sure that there is
some difference between the different F1 cars.
Sincerely,
-- Doug
Milliken Research Associates Inc.