Suspension Systems

Every spring, no matter whether it is a torsion, leaf, or coil spring must compensate for road surface irregularities. Keep the suspension systems at a predetermined height, and support the additional weight without excessive sagging.

Each one of these functions is vital in providing comfort, precise handling, and load-bearing ability in modern vehicles – three areas that are likely to raise customer concerns.

The steel multi-leaf spring, historically speaking, is one of the most popular spring designs in suspension systems. There are many benefits to the leaf spring. It acts as a spring and attaches directly to the chassis.

One “mono-leaf spring” may be used in certain applications. Leaf springs are used in trucks with solid drive axles. However, a transverse leaf spring can be combined with an independent suspended rear axle to create a lightweight rear suspension system for performance road cars.

You can adjust the number, thickness, and length of the spring leaf leaves to meet different load-bearing or ride control requirements.

A leaf spring can also act as a rebound dampener because of friction between the leaves. A steel spring can sometimes be replaced by a plastic unit which significantly reduces the unsprung weight and resists corrosion by road salt and other elements.

Torsion Springs

For vehicles with SLA suspension systems, Torsion-bar suspension systems are used for years. The torsion bar is a four-foot-long round bar that is designed to bend as weight is added to the suspension system. Torsion bars are usually preloaded with a clockwise or counterclockwise twist. This ensures that they will only fit the vehicle on which they were designed.

Torsion bars offer compactness and are lightweight, which are two of the many benefits. To adjust the suspension height, torsion bars are able to be used because the tension of the torsion bars is controlled using a threaded screw adjustment. Torsion bars can also be attached to the lower or upper control arms to increase the versatility of the design.

Coil Spring

A coil spring’s function can be understood better if it is viewed as a torsion bar that is long and thin, wound into a coil shape. Because the coiled wire twists during the spring’s compression/extension cycles, the coil spring actually operates on the same principle as a torsion bar.

A coil spring takes up a very small area so it can be used with a variety of suspension systems design, including MacPherson Strut, solid-axle with trailing arms, or any SLA suspension system that uses a spring or coil-over-shock absorber configuration.

Modern imports use the MacPherson-strut coil spring design in various variations. The characteristics of the coil spring are determined by the wire gauge, length, overall dimension, and the number of coils.

A coil spring can also be made variable-rate to increase load-bearing capacity by being compressed. These coil springs can be used in chassis configurations that are frequently carrying heavy loads.

How Springs Works

According to the principle of sprung/unsprung weight ratios, springs cushion the vehicle’s ride. Unsprung weight is 100% for a farm wagon that has no springs. If springs are placed between the chassis, axles, and farm wagons, the sprung to unsprung ratio could be 90% for the chassis weight, and 10% for the axle and wheel weight.

The springs absorb impact from road imperfections as a vehicle speeds up. To keep the wheels and axles in contact with the road surface, the spring rate must be higher as the vehicle speeds increase. High-performance vehicles have stiffer suspension systems than regular passenger cars.

A spring compressed to its maximum length will cause it to extend violently. To dampen this cycle shock absorbers are needed. A spring’s violent compression or extension could cause vehicle control problems on rough roads without dampening.

The vehicle will experience the poor ride, steering response, and handling control as rebound control wears out. Tire wear will also be increased by tire scuff due to suspension geometry that is outside its normal range. Manufacturers of shock/struts insist on regular inspections and replacement of worn units.

The compression and extension characteristics must match those of the spring. For normal driving, dampening and rebound control may not be necessary because stiffer springs are less likely to experience extreme travel ranges. Because they experience greater compression and extension, softer springs may need more dampening to make the shock absorber work harder.

It is important to include the sway bars in any shock absorber or spring package for performance applications. After driving for a few thousand miles, the vehicle’s suspension height will likely change slightly. Retorquing suspension bolts is recommended to prevent tire wear and safety concerns that may arise from a spring replacement. Contact us for more information on the role of springs in suspension systems!