Yes
In spite of the many signi cant improvements in car chassis design over the past two
decades, steering drift during braking where the driver must apply a corrective steering torque in
order to maintain course can still be experienced under certain conditions while driving. In the past,
such drift, or `pull¿, would have been attributed to side-to-side braking torque variation [1], but
modern automotive friction brakes and friction materials are now able to provide braking torque
with such high levels of consistency that side-to-side braking torque variation is no longer regarded
as a cause of steering drift during braking. Consequently, other in uences must be considered. This
paper is the rst of two papers to report on an experimental investigation into braking-related steering
drift in motor vehicles. Parameters that might in uence steering drift during braking include suspension
compliance and steering o set, and these have been investigated to establish the sensitivity of
steering drift to such parameters. The results indicate how wheel movement arising from compliance
in the front suspension and steering system of a passenger car during braking can be responsible for
steering drift during braking. Braking causes changes in wheel alignment which in turn a ect the toe
steer characteristics of each wheel and therefore the straight-line stability during braking. It is concluded
that a robust design of suspension is possible in which side-to-side variation in toe steer is
not a ected by changes in suspension geometry during braking, and that the magnitude of these
changes and the relationships between the braking forces and the suspension geometry and compliance
require further investigation, which will be presented in the second paper of the two.