by Mark Worman from Graveyard Carz
A 1970 Plymouth Barracuda Convertible or an identically equipped 1970 Plymouth Barracuda hardtop?
While the initial appearance of a car with no roof would lead you to believe it's lighter than one with a roof, it's not...and here's why.
A hardtop vehicle, by nature, is a more solid car than one missing it's top. The roof on a unibody car makes up a large portion of the structural integrity of the overall body. When the top is removed, such in the case of a convertible, reinforcements are added to the body to compensate for the missing roof structure. Items such as frame rail connectors, IE "torque boxes" are added at the front and rear of the floor pan to join the rocker panels to the floor sections.
In addition to this, a section of thick, solid steel angle iron is welded inside each rocker panel. While this does add strength to the car, it also adds weight.
Also contributing to the weight of a convertible vehicle, is the actual top mechanism itself. This includes the solid iron frame work of the top , as well as the hydraulic pump, pistons, cables and lines, etc. (optional on E bodies) that allow the top to go up and down.