Suspension Systems

Spring types differ depending on vehicle weight requirements and load capacities. There are four kinds of Springs used in suspensions today. Coil springs or the most popular, leaf springs, torsion bar and air. Coil springs coming three different types. There are tapered end coil springs, tangential end coil springs, and pigtail coil springs. Coil springs consist of the spring wire that is seated and wound into coil. Leaf springs are attached to the vehicle using u-bolts and hangers. Torsion bars use a straight spring and a steel bar. Air suspension systems use an air spring, diaphragm and plunger. Some vehicles use airbags. The conventional springs are replaced by four airbags or air spring assemblies to support the vehicle and control its height. Vehicle ride height is controlled by springs and must be correct in order to set the vehicle alignment. Torsion bar suspensions can be adjusted to correct the vehicle height. The spring right is the force required to compressed the spring 1 inch.

Shocks

Spring oscillations are dampened by shock absorbers. Shock absorbers study the ride, reduce sway and pitch and resist rapid movements of the vehicle. There are various types of shocks including coil over shock, air shock, gas shock and variable damping shock. Coil over shocks are usually heavy-duty and use a coil spring. These shocks compensate for heavier loads.

Front Suspension Systems

There are two types of front suspension systems. Independent front suspension systems can be divided into two separate applications. Twin I-beam front suspensions are made up of two separate beam axles that support each front wheel. Coil springs provide suspension, and radius arms prevent backward or forward movement of the axles. Short/long arm (SLA) front suspensions include a combination of control arms and ball joints. Ball joints that receive force from a coil spring or torsion bar are considered load carrying, while follower ball joints connect the other end of the knuckle to the load carrying control arm. When inspecting suspension pivots look for worn ball joints that cause erratic steering free play, tire wear and noise.

Struts

A coil spring is the most common on a strut. Modified McPhearson struts use coil springs on the lower ball joint.

Rear Suspension Systems

There are various types of rear suspension systems including solid, leaf spring, coil spring, torque tube or arm and independent. Solid rear suspension systems may use leaf springs, coils, torsion bars or air bags. Leaf spring rear suspension systems use leaf springs and provide both axle location and torque transfer. Coil spring rear suspension systems require usually two lower and one or two upper control arms for location and torque transfer. Torque tube or arm rear suspension systems use coil springs which provide only suspension and not location.

Stabilizer Bar

The sway bar helps limit body lean on sway while cornering and may be used in front suspension or in both front and rear suspension.