there are countless modifications that can be done to your suspension so ill do my best to explain some of the options.
the most popular modification to be made would have to be lowering springs.
Springs absorb and store road shock caused by bumps, dips, cracks, and so forth. They absorb this shock by either compressing or extending. When a car’s wheel goes over a bump and gets pushed upward, the spring absorbs that additional load, keeps the road shock from reaching the chassis, and makes sure the tire maintains contact with the pavement.
How much a spring compresses or extends is determined by its “spring rate.” Spring rate is measured in pounds per inch of deflection; for example, 100 pounds per inch. So, say a load of 200 pounds is applied, the spring will deflect 2 inches. Spring rate comes from various factors. For a coil spring, this includes the number of active coils, the diameter of the coils, and the diameter of the spring wire. The fewer coils a spring has, the higher the spring rate it will have.
The design of a spring affects how well the vehicle will ride and handle. A spring that absorbs lots of energy will generally offer a comfortable ride. After all, it can absorb most of the road shock (energy) that is being generated by the road surface. But there are always engineering trade-offs. This kind of spring generally requires a higher vehicle ride height, which will cause the vehicle to feel unstable during cornering. This instability is because the more distance a spring compresses or extends, the more the vehicle “rolls” around on its suspension. This rolling is called weight transfer, and it is caused by centrifugal force acting on the weight of the vehicle as it goes around a corner. Weight transfer can overload a tire’s grip, which ultimately hurts traction, and therefore handling.
Shock Absorbers
The other main part of a car’s suspension is the shock absorber. Contrary to its name, a shock absorber plays a minimal role in absorbing impacts taken by the suspension. That’s the spring’s job. A shock absorber dampens road impacts by converting the up and down oscillations of the spring into thermal energy.
People who live and breathe shock absorbers (like us 240sx owners) don’t like the term shock absorbers; they prefer “dampers.” The unwashed masses – that’s you and me – just call them shock absorbers.
Without a shock absorber, a spring that has absorbed energy will release it by oscillating at an uncontrolled rate. The spring’s inertia causes it to bounce and overextend itself. Then it recompresses, but again travels too far. The spring continues to bounce at its natural frequency until all the energy originally put into the spring is used up by friction. This effect can be quite detrimental to the stability of a vehicle.
Confused? OK, here’s an analogy. If you have a Slinky lying around – and who doesn’t these days? – you can use it as an example. Hold up a compressed Slinky in the air with your hand. Now hold just one end and let the other drop. The Slinky will absorb the potential energy caused by gravity (just like how a car’s spring absorbs road shock) and then bounce up and down, up and down (aka: oscillate), for a long time. This what an automotive spring does if it doesn’t have a shock absorber attached to it.
Perhaps you’ve heard the word “strut,” or, more formally, MacPherson strut. Struts are simply shock absorbers used as major structural members. For struts, the shock absorber is placed inside the coil spring. In addition to saving space, it often costs less. Many cars use a strut design.