(1) MacPherson strut type
This is the most widely used independent suspension system for the front suspension of small and medium sized cars. This type is also used as the rear suspension of FF cars. Characteristics:
- The construction of the suspension is relatively simple.
- Since there are a small number of parts, it is light, so unsprung weight can be reduced.
- Since the space taken up by the suspension is small, the usable space in the engine compartment can be increased.
- Since the distance between suspension support points is great, there is little disturbance of the front wheel alignment due to installation error or part manufacturing error. Therefore, except for toe-in, alignment adjustments are ordinarily unnecessary.
On the MacPherson strut type suspension, the shock absorbers act as part of the suspension linkage, bearing the vertical load. However, because the shock absorbers are subjected to the load from the tires, they bend very slightly. This causes lateral stress to be generated, creating friction between the piston rod and the rod guide, and between the piston and the inner shell, causing abnormal noises and adversely affecting riding comfort. These problems can be minimized by off-setting the springs from the centerline of the strut or shock absorber so that reactive forces are generated in opposition forces.
(2) Double wishbone type
This type is used widely for the front suspension of small trucks and for the front and rear suspensions of passenger cars.
In this type of suspension, wheels are mounted to the body via upper and lower arms. Suspension geometry can be designed as desired according to the length of the upper and lower arms and their mounting angles. For example, if the upper and lower arms are parallel and have equal length, the tread and the tire-toground camber of the tire will change. As a result, it is not possible to obtain adequate cornering performance. In addition, the changes in the tread will cause excessive tire wear. To solve this, a design is normally employed in which the upper arm is made shorter than the lower arm so that the tread and the tire-to-ground camber of the tire fluctuate less.
Semi-trailing arm type Semi-trailing arm type is used for the rear suspension in a few models. With this suspension, the amount by which the toe angle and camber change (due to the up-and-down motion of the wheels) can be controlled at the design stage, in order to determine the handling characteristics of the vehicle.