Chapter 5 Front Suspension Systems 89
improve ride, allow for heavier loads, or reduce the space
taken up by the front suspension.
Spring Separate from Strut
On some vehicles with MacPherson struts, the spring
is separate from the strut assembly, Figure 5-12. The spring
is installed between the lower control arm and the frame.
Other components are identical to those used in a conven-
tional MacPherson strut system.
Location of Turning Bearing
Some MacPherson struts have the turning bearing
installed at the bottom of the spring. This allows the spring
to stay in place during turns. Another feature of these struts
is that the cartridge can be replaced without removing the
strut from the vehicle.
Use of Additional Control Arms or Links
On a few vehicles, the MacPherson strut assembly
uses an additional control arm or a series of links. The
control arm or link assembly is attached to the top of the
steering knuckle. When this design is used, the bottom of
the strut assembly can pivot in relation to the steering
knuckle. The use of upper and lower control arms improves
ride quality and keeps the tire surface in closer contact
with the road when driving over bumps or depressions.
The two major examples of this design are the
double wishbone suspension, Figure 5-13, and the
multilink front suspension, Figure 5-14.
Conventional Independent Front
Suspensions
All modern conventional independent front
suspensions consist of upper and lower control arms,
which are attached to the steering knuckle through ball
joints. Each control arm is attached to the frame through
Upper arm
Wheel
travel
arc
Coil spring
Shock absorber
Stabilizer bar
Lateral rod
Lower control arm
Figure 5-5. When the tire and wheel travel up and down in an
arc, tire-to-road contact is improved. (Sterling)
Strut damper
Spring
Steering
knuckle
Lower
strut
mounting
Control
arm
Figure 5-6. Lower strut mounting held to the steering knuckle
with bolts and nuts. (General Motors)
MacPherson
strut
assembly
Steering arm
Steering
arm
Figure 5-7. On this lower strut mounting, the suspension arm is
an integral part of the knuckle. (Moog)