Suspension and Steering, Page 1 of 4
Links to topics on page 1 Links to topics on page 2 Links to topics on page 3 Links to topics on page 4
Types of front suspensions
See Figures 1 thru 7 The most common front suspensions used on vehicles today are the independent (2 unequal length control arms) and McPherson strut suspension systems (used on front wheel drive and some rear wheel drive vehicles).
Figure 1 The two most common front suspension types used on vehicles today.
|
Figure 2 On this design, the coil spring is mounted on top of the upper control arm with the shock absorber in the center of the coil spring. Only the upper control arm is of the A-arm design.
|
Figure 3 Typical unequal length A-arm suspension used on rear-wheel drive sedans. In this design, the shock absorber and coil spring are positioned between the upper and lower control arms. Note that the control arms (A-arms) are not the same length.
|
Figure 4 This independent front truck suspension is very similar to the unequal length A-arm suspension used on rear-wheel drive sedans. It functions in the same manner, but the components are of a heavier duty construction to handle the added stress.
|
Figure 5 This straight I-beam front suspension, used mostly in heavy-duty trucks, is uncomplicated and meant to handle heavy loads, rather than give a comfortable ride.
|
Figure 6 This four-wheel-drive suspension is basically the same as an I-beam suspension, except that a front drive axle takes the place of the I-beam.
|
Figure 7 The twin I-beam front suspension is used almost exclusively by Ford trucks. The coil spring is mounted between the frame and an I-beam that carries each wheel. The I-beam is pivoted at the other end, and a radius rod serves to locate the fore-and-aft position of each I-beam.
|
Independent front suspension
See Figures 2 and 3 This is also called an unequal length A-arm or control arm type, because the upper and lower control arms attached to the frame are of different lengths. This design is typical of American sedans and is designed this way to reduce tire scuffing. Ball joints are used to attach the outer ends of the control arms to the spindle. This type of front suspension most often uses coil springs between the control arms, though they can be positioned between the control arm and frame or even on top of the upper control arm. Shock absorbers are used to dampen vibrations. McPherson strut
See Figure 8 McPherson strut front suspension differs considerably from unequal length A-arm suspension. McPherson strut suspension is found most frequently on compact and subcompact cars, both domestic and imported. With this type of suspension, the shock absorber, strut and spindle are a combined unit, which is supported by the coil spring at the upper end and the lower control arm (sometimes called track control arm or transverse link) at the bottom. Another type of front strut suspension is referred to as a modified McPherson strut suspension, which is the same as the regular McPherson strut unit except the coil spring is mounted separately from the strut, between the lower control arm and the frame. There is only one ball joint in this design, and it is attached to the lower part of the spindle. Generally, this ball joint is not a load carrying ball joint, but a follower ball joint, which means it is isolated from vehicle weight. The shock absorber is built into the strut outer casing and, except for the modified McPherson strut, a coil spring sits on a seat welded to this casing. The upper mount of the shock absorber bolts to the vehicle body. On some models, the strut cartridge may be replaced, while on others the entire strut must be replaced. Due to the design of this type of suspension, the only front-end alignment procedure possible is toe-in adjustment, since caster and camber are fixed.
Figure 8 McPherson strut type front suspensions are used on most of today's passenger vehicles.
|
Continue to page 2 of Suspension and steering
Back to top of page
Return to ProCarCare Car Care Encyclopedia index
©1998 W. G. Nichols - Chilton's Easy Car Care
|
