Wheel Alignment And Steering Angles; Definitions; Checking And Adjustment - Opel Zafira B MPV 2006 Owners Workshop Manual

23
Wheel
alignment
and steering
angles -
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information
Definitions
1 A car's steering and suspension geometry
is defined in four basic settings - all angles are
expressed in degrees (toe settings are also
expressed as a measurement); the steering
axis is defined as an imaginary line drawn
through the axis of the suspension strut,
extended where necessary to contact the
ground.
2 Camber is the angle between each
roadwheel and a vertical line drawn through its
centre and tyre contact patch, when viewed
from the front or rear of the car. Positive
camber is when the roadwheels are tilted
outwards from the vertical at the top; negative
camber is when they are tilted inwards. Slight
adjustment of the front camber angle is
possible, by altering the position of the swivel
hub at its attachment to the front suspension
strut. The rear camber angle is not adjustable.
3 Castor is the angle between the steering
axis and a vertical line drawn through each
roadwheel's centre and tyre contact patch,
when viewed from the side of the car. Positive
castor is when the steering axis is tilted so that
it contacts the ground ahead of the vertical;
negative castor is when it contacts the ground
behind the vertical. The castor angle is not
adjustable.
4 Toe is the difference, viewed from above,
between lines drawn through the roadwheel
centres and the car's centre-line. 'Toe-in' is
Suspension and steering 10•17
when the roadwheels point inwards, towards
each other at the front, while 'toe-out' is when
they splay outwards from each other at the
front.
5 The front wheel toe setting is adjusted by
screwing the track rod in or out of its balljoints,
to alter the effective length of the track rod
assembly. The rear wheel toe setting is not
adjustable.
Checking and adjustment
6 Due to the special measuring equipment
necessary to check the wheel alignment
and steering angles, and the skill required to
use it properly, the checking and adjustment
of these settings is best left to a Vauxhall/
Opel dealer or similar expert. Note that most
tyre-fitting shops now possess sophisticated
checking equipment.