Method of assembling a crossbar with a dashboard, and a centering device

A method of assembling together an elongate air-flow crossbar and a dashboard, by relative movement between the crossbar and the dashboard in a first direction substantially perpendicular to the length of the crossbar, so that at least one centering device of the crossbar penetrates into an orifice of the dashboard in the first direction, the method being of the type that comprises:

• an operation of assembling at least one air-flow element on a metal crossbar by moving in at least one direction substantially transverse to said first direction;
• and
• an operation of assembling the dashboard onto the crossbar by moving the dashboard in the first direction so that the centering device penetrates into the orifice;
• the method further comprising:
• before the operation of assembling the air-flow elements on the metal crossbar, placing a centering device base on the metal crossbar, the base being of height that is small enough to avoid hindering the operation of assembling the air-flow elements to the metal crossbar;
• and
• after the operation of assembling the air-flow elements on the metal cross-bar, and before the operation of assembling the dashboard on the crossbar, placing a centering device body on the centering device base so that the base and the body of the centering device are fastened together.