Common Suspension terms

[twistedframe]

The sway bar thread made me think it might be good to have a thread dedicated to suspension and brake terms and parts all in one place. This is just a simple list I have come up with and please feel free to add anything that you would like! I started with just some suspension parts for now and will update with brakes later one.

Coil Springs - This is the most common type of spring used on modern cars and trucks. The main job of a coil spring is to hold the weight of the car (AKA sprung mass), as well as absorb the motion of the wheels. Hypothetically you could drive a car with only coil springs and it would hold the weight of the car you would just have a very bouncy ride.


Sprung Mass - Sprung mass is any part of a car or truck that is supported buy the springs, whether they be coil, air, leaf, or torsion bars.

Unsprung Mass - Unsprung mass is defined as any part of the car or truck that is between the pavement and the bottom of the spring. this generally includes wheels, brakes, some steering parts, and sometimes lower suspension parts like knuckles and lower control arms. Just remember that 1 pound of unsprung weight is equal to 1.4 pounds of sprung weight.

Dampers (AKA shock absorbers) - The main job of shock absorbers is to damper spring oscillations. They do this by turning the kinetic energy of the spring movement into heat energy that is dissipated through hydraulic fluid inside the shock body. Without them springs would contract and extend to their full lengths uncontrollably until all the energy was expended.


Struts - A shock absorber with a spring already mounted on it. It performs the functions of shocks and coil springs all in one unit. Struts are used on McPherson as well as double wishbone suspension set ups.

[Highrev1]

Progressive rate vs Fixed rate spring. IE eibach pro kit vs Ground control coilovers.

Progressive rate spring has an increasing spring constant. For example, if the first inch of spring motion requires 100 pounds of force, the second inch would require more than an additional 100 pounds, and the third inch would require still more. Progressive-rate springs become stiffer as they are compressed.

Unlike single-rate springs, which have a fixed spring rate. A fixed rate spring is much better for tuning due to compression of the spring effects spring rate. BUt progressive rate is more comfortable for the street.