GA-600S
3D Wheel Aligner User Manual
1-4
1. 3. 5 Toe-out on turn
Toe-out on turns is defined as the difference of the steering angle between the two
front wheels when turning left or right by 20°. see Figure 1.5.When the vehicle turns,
the inner wheel angle is always bigger than the outer wheel, difference is about 2
degrees, the purpose is to make the vehicle turn by referenced to the instant center
point of the extend line of back axis.
Figure 1. 5
Figure 1. 6
1. 3. 6 Thrust Angle
Definition: The angle between the vehicle’s centerline and the vehicle thrust line. When
driving, the front wheels and the rear wheels should pull to the same side if the thrust
angle is not zero. When thrust line is at the left side of the vehicle’s centerline, the
thrust angle is positive, otherwise is negative. The existence of the thrust angle causes
the vehicle’s rear body pull to one side. In order to drive the vehicle straight-ahead, the
front wheels have to turn to the direction of thrust line. If thrust angle compensation is
not done for front toe, the steering wheel must be turned to one side when driving
straight-ahead. If rear toe can be adjusted, the thrust angle should be adjusted close
to zero. The direction of thrust line is the actual driving direction of the vehicle, which
is determined by rear toe. When the direction of thrust line doesn’t coincide with the
geometric centerline of the vehicle, the steering wheel must be turned by some
degrees to keep the vehicle driving straight-ahead, so that unbalance phenomenon of
the steering wheel is caused. At the same time, the traveling paths of rear wheels don’t
coincide with that of front wheels. This kind of phenomenon is called Rear Wheel
Lateral Move. If ignore the thrust line, the veracity of alignment cannot be ensured.
This is the main reason of the steering deflection. If you select the thrust line as the
measurement datum, you can perform the following operation procedures:
After adjusting rear toe to the specified value (OEM Specifications), the thrust line will
coincide with the vehicle’s centerline. For the vehicle with adjustable rear suspension,
rear toe should be adjusted to keep the thrust angle close to zero.
No matter the
thrust angle is zero or not, the steering wheel can be adjusted balanced if you take the
thrust line as alignment datum. If rear toe cannot be adjusted, please adjust front toe,
and keep it be same with rear toe, and then set them to the angle by which the steering
wheel can be balanced.
