A vehicle’s suspension allows the tires and wheels to move independently of the chassis. Suspension components also control fore/aft and lateral (side to side) wheel location. Components come in many different designs, such as control arm, A-arm, trailing link, trailing arm, torque arm, Panhard rod and Watts link.

Suspension Pivot Points
Suspensions require pivot points to function and bushings are fitted in at least one pivot point. Rubber bushings are most often used by manufacturers because they insulate well against noise and vibration. If your vehicle has high mileage, you may want to have new bushings installed, since worn ones contribute to poor suspension control. Some aftermarket firms sell urethane plastic bushings to replace factory ones. Based on the location and bushing hardness, urethane can cause a harsh ride and increased interior road noise. Depending upon where the urethane is fitted, they can also cause handling problems in some suspensions.

Anti-roll Bars
Anti-roll bars help reduce body roll or lean. By using them, vehicle manufacturers can reduce spring stiffness, which improves ride quality. Plus, this helps maintain tire adhesion in many driving situations. Anti-roll bars can also be used to improve handling. However, bars that are too large in diameter (stiff) can reduce tire adhesion on slick surfaces. This is especially true driving on snow and ice. They can also be a disadvantage for serious off-road driving.

Springs
Springs support the vehicle chassis or body and they can be considered the suspension’s “heart”. Their “energy memory” is what allows suspension movement. Body motion, or wheel/tire motion transmits kinetic energy (or load) to compress the spring. When the energy dissipates, the spring decompresses by releasing its stored energy and returns to its normal height.
Springs maintain ride height, influence body motion (pitch and roll) and ride quality as well as tire adhesion. Springs can be in coil, leaf or torsion bar form. Rubber air bags are also a form of spring. Generally, the heavier and higher a vehicle is, the stiffer the spring needs to be. A common way to lower a vehicle for improved handling or appearance is installing shorter springs. But be aware that a stiffer (shorter) spring will cause some loss of ride quality and reduced suspension travel. Excessive lowering will cause a very harsh ride, poor handling and possible suspension damage.

Shock Absorbers
Springs, suspension components and pivot bushings allow suspension movement, but something is needed to eliminate excess movement. Without proper control, suspension motion will become excessive and even violent. If springs are the heart, then shocks can be considered the brains. Shocks use hydraulic friction to damp out or resist suspension movement. While springs are “load sensitive” devices, shocks react to suspension velocities. They remove kinetic (or movement) energy from the suspension and convert it into heat, which is dissipated into the air. Shocks work in two directions. Compression (or closing) direction works with the spring to reduce bottoming and help keep the tire in contact with the road surface. Rebound (or extension) controls the release of spring energy as it returns to its normal height, so the vehicle doesn’t bounce or float. Excessive shock control delivers a harsh ride and reduced traction, while too little control allows the chassis and tires too much movement.

The challenge for TOKICO engineers is designing a shock that provides the correct amount of control for a wide range of suspension movement. Meeting this challenge requires experience, a sophisticated design and quality. For more information, see Evaluating Your Shocks.

As you navigate this site, you’ll find important technical information on how shocks function and why TOKICO shocks can improve your vehicle’s performance.