Replacing the roof panel of the car body (Audi 100 C3)

Chisel off the roof panel as close to the gutter as possible. Strip the top ends of the middle pillars, saw off the ends of the front and rear pillars. Drill out the spot welds around the roof perimeter. Remove burrs at the spot welds. Straighten and prepare the mating surfaces for welding. Cut out and replace damaged parts if necessary. Install, center and clamp the new part. Spot weld the part around the perimeter (connection points with the front and rear cross members, as well as longitudinal reinforcements). Weld the front and rear pillars together using electric welding, clean the seams, tin them and level the surface at the welding points.