Wheel Alignment - Geely EC718 2009 Workshop Manual

4-58 Wheels and Tires
4.4.3 System Working Principle

4.4.3.1 Wheel Alignment

Driver turning the steering wheel turn the vehicle to the desired
direction. However, if driving on the straight road, driver must
adjust the steering wheel from time to time in order to maintain
the vehicle straight-line driving, or turning at a corner, driver
makes a lot of effort, the driver will be under physical and
mental stress. To address this problem and to prevent
premature tire wear, according to certain requirements, wheels
are installed on a vehicle body (or chassis) at a certain angle.
These angles are called as "Wheel Alignment". It is a
comprehensive term referring to the front and rear axles,
wheels, steering components and suspension components
relative angles.
Correct wheel alignment makes the steering easy. On the
straight road, the driver only needs minor adjust to the steering
wheel to keep the vehicle move straight ahead, and only a little
effort to turn the vehicle. In other words, if various angles
constitutes the "wheel alignment" are adjusted correctly, the
turning will be easy. But even if one of them is adjusted
improperly, it may have the following problems: steering
problems; poor steering stability; poor steering wheel return;
reduced tires life.
Vehicle positioning angles include: front toe, camber, caster,
kingpin inclination angle, steering angle, tolerance angle,
forward angle, grinding tire radius. These angles and size
depend on the vehicles suspension systems, drive system
(Front-engine front-wheel drive or front-engine rear-wheel
drive, two-wheel drive or four-wheel drive), and the steering
system (manual or power steering shift). Adjusting these
elements will optimize the driving performance and steering
stability and prolong the service life of components.
Maintenance is usually recommended only for front toe
adjustment.
EC718/EC718RV EC715/EC715RV 10/2009
1. Front Toe
Front
Positive Front Toe Zero Front Toe
(Wheel Inward)
(Wheel Parallel)
Rear
Front toe is used to measure wheel rotation, or deviation from
the vehicle centerline. Another way to understand the front toe
is that two front wheels distance relative to the same vehicle
rear wheels distance. If all the wheels are completely parallel,
then these two measurements should be equal and the front
toe should be zero. If the front wheels tilt inward, the front toe
is positive. When the front wheels tilt outward, the front toe is
negative. Positive and the negative front toes are usually
referred to as the front wheel toe-in and front wheel toe-out.
Front toe function is to compensate for tire drag due to camber
and road surface resistance caused the inward or outward
rolling trend to keep the vehicle straight ahead.
2. Camber
Vertical
Positive Camber
Reference Line
Concave
Negative Camber
Suspension System
Front
Negative Front Toe
(Wheel Outward)
Rear
FE04-1012b
Positive
Zero
Camber
Camber
Vertical Reference Line
Convex
FE04-1013b