Learning Objective: Automotive front suspension
After finishing this chapter, you should be familiar with these fundamental learning objectives:
SUSPENSION PRINCIPLES
TYPES OF SUSPENSIONS
.
Solid I-beam axle with leaf springs.
TYPES OF SUSPENSIONS
A typical independent front suspension used on a rear-wheel-drive vehicle. Each wheel can hit a bump or hole in the road independently without affecting the opposite wheel.
Most vehicles today use a separate control-arm-type of suspension for each front wheel, which allows for movement of one front wheel without affecting the other front wheel.
This type of front suspension is called independent suspension.
SHORT - LONG ARM (SLA)
MacPHERSON STRUT
TWIN I-BEAM SUSPENSION
SUSPENSION PARTS�CONTROL ARMS
SUSPENSION PARTS�CONTROL ARMS
Control arms are used to connect the steering knuckle to the frame or body of the vehicle and provide the structural support for the suspension system.
SUSPENSION PARTS�STEERING KNUCKLES
SUSPENSION PARTS�STEERING KNUCKLES
The steering knuckle used on a short/long-arm front suspension.
SUSPENSION PARTS�STEERING KNUCKLES
FIGURE 6–32 A kingpin is a steel shaft or pin that joins the steering knuckle to the suspension and allows the steering knuckle to pivot.
SUSPENSION PARTS�THE SPINDLE
The spindle supports the wheels and attaches to the control arm with ball-and-socket joints called ball joints. The control arm attaches to the frame of the vehicle through rubber bushings to help isolate noise and vibration between the road and the body.
SUSPENSION PARTS�BALL JOINTS
BALL JOINTS�BALL JOINT DESIGN
SUSPENSION PARTS: BALL JOINTS
The lower ball joint is load carrying in this type of suspension because the weight of the vehicle is applied through the spring, lower control arm, and ball joint to the wheel.
SUSPENSION PARTS�BALL JOINTS
The upper ball joint is load carrying in this type of suspension because the weight of the vehicle is applied through the spring, upper control arm, and ball joint to the wheel. The lower control arm is a lateral link, and the lower ball joint is called a follower ball joint.
SUSPENSION PARTS�Non-Load-Carrying Ball Joints
Stabilizing / Follower ball joints:
Low Friction ball joints
SUSPENSION PARTS�STABILIZER BARS
SUSPENSION PARTS STABILIZER BARS
As the body of the vehicle leans, the stabilizer bar is twisted. The force exerted by the stabilizer bar counteracts the body lean.
SUSPENSION PARTS �STRUT RODS
The strut rods provide longitudinal support to the suspension to prevent forward or rearward movement of the control arms.
SUSPENSION PARTS�STRUT RODS
Struts rods are only used when there is only one lower control arm bushing and not used where there are two lower control arm bushings.
4 BAR AXLE
Review
What is the difference between an SLA suspension and a MacPherson Strut suspension?
To what are the control arm(s) connected?
To what is the spindle connected?
What is the difference between a loaded ball joint and a follower ball joint?
What is the purpose of a stabilizer bar?
What type of control arm requires a strut bar?
SUSPENSION PARTS�SPRINGS
SUSPENSION PARTS�COIL SPRINGS
SUSPENSION PARTS�COIL SPRINGS
This replacement coil spring is coated to prevent rust and corrosion and colored to help identify the spring and/or spring manufacturer.
SUSPENSION PARTS �COIL SPRINGS
Coil spring ends are shaped to fit the needs of a variety of suspension designs.
SUSPENSION PARTS�COIL SPRINGS
A constant-rate spring compresses at the same rate regardless of the amount of weight that is applied
Variable-rate springs come in a variety of shapes and compress more slowly as weight is applied.
Should I Cut My Coil Springs?
SUSPENSION PARTS �TORSION BARS
A torsion bar resists twisting and is used as a spring on some cars and many four-wheel-drive pickup trucks and sport utility vehicles. The larger the diameter, or the shorter the torsion bar, the stiffer the bar.
SUSPENSION PARTS �TORSION BARS
Longitudinal torsion bars attach at the lower control arm at the front and at the frame at the rear of the bar.
SUSPENSION PARTS �TORSION BARS
One end of the torsion bar attaches to the lower control arm and the other to an anchor arm that is adjustable.
SUSPENSION PARTS �LEAF SPRINGS
SUSPENSION PARTS �LEAF SPRINGS
A typical leaf spring used on the rear of a pickup truck showing the plastic insulator between the leaves, which allows the spring to move without creating wear or noise.
SUSPENSION PARTS �LEAF SPRINGS
All multileaf springs use a center bolt to not only hold the leaves together but also help retain the leaf spring in the center of the spring perch.
SUSPENSION PARTS �LEAF SPRINGS
When a leaf spring is compressed, the spring flattens and becomes longer. The shackles allow for this lengthening. Rubber bushings are used in the ends of the spring and shackles to help isolate road noise from traveling into the passenger compartment.
SUSPENSION PARTS �LEAF SPRINGS
Many pickup trucks, vans, and SUVs use auxiliary leaf springs that contact the other leaves when the load is increased.
LEAF SPRINGS�COMPOSITE LEAF SPRINGS
A fiberglass spring is composed of long fibers locked together in an epoxy (resin) matrix.