Why you need struts?

Answer 1

Struts are a suspension design that diminishes the problems associated with an "un-sprung mass".

The un-sprung mass is the mass of the wheel, tire axle and whatever else follows the road surface.

The vehicle floats along on the springs, hopefully making a smoother, more comfortable ride. When a tire hits an uneven part of the road surface, the mass/inertia of the vehicle causes the springs to deflect, allowing the tire to move over the surface of the road imperfection while, hopefully, not transferring too much vertical acceleration into the vehicle.

Here's where the struts come in:

Struts are a lightweight version of the shock absorber/suspension/spring assembly.

Once the spring deflects, the wheel goes up. The spring of the strut is still pushing down on the tire/wheel assembly and once the vehicle is past the road imperfection the tire will be pushed back down. Now the un-sprung mass has vertical inertia.

With inertia of the the un-sprung mass comes the potential for harmonics, meaning that the un-sprung mass will bounce.

Struts and their predecessors "shock absorbers" dampen out the harmonics caused by hitting such road imperfections. By minimizing the bouncing of the wheel, the driver is better able to control steering and stopping.

There is quite a bit of confusion about what struts and shock absorbers do in a vehicle and while the struts are a combination of a shock absorber and a shock absorber, most of the time people only replace the central shock absorber part of the strut.

For more information go to: http://en.wikipedia.org/wiki/MacPherson_strut

While there are disadvantages to a Macpherson Strut suspension, one of the major advantages is that a vehicle with a single wishbone ends up with a lower "un-sprung mass"