strut bar

I am stupid.
Whats a strut bar do?

it helps to reduce body roll and flex.

im sure others will be able to explain better and how.

A strut bar normally runs between the top of the two suspension towers in most commonly a MacPherson Strut suspended car. The Macpherson Strut suspension is the most common suspension system in Front Wheel Drive cars (except the Honda Civic and Accords which use a double wishbone arrangement).

"Mac Struts" consist of a strut with a lower locating arm and usually a anti-sway bar controlling the lateral motion.

In any case, a strut bar helps adds stiffness to the chassis between the suspension on the respective parts of the car and reduces the unwanted effects of chassis flex betwen the right and left sides of the car. In other words, it helps ensure that the respective suspension uprights (in the case of MacStruts, the struts or in a wishbone suspension the spindle) stay the same distance apart and the respective suspension geometry stays consistent. It also is usually lighter than a wholesale increase in bending and torsional strength which is usually achieved by adding more elements to the chassis.

imagine your suspension in your car's body being a box without a top. push on the sides.
they flex in
put a top on the box that connects the sides. push on the top

not as much flex...

yes? good...