Often times collectors/vintage racers are faced with the dilemma of deciding whether to re-body their newest vintage racecar or repair the existing sheet metal panels. If the car has a body made of aluminum it is almost always better to re-body than repair, with a few notable exceptions.
Aluminum, over time and use becomes work- hardened and brittle. In addition, the panels most likely have been repaired and straightened over the years; this also hastens the process of work-hardening. If the panels have been repaired, someone used a file to metal finish after the panels had been planished smooth. If done improperly this can shave .030 to .040 from the surface of a fender. Couple this with the fact that the substrate has corroded and absorbed forty plus years of road debris, brake dust etc. it becomes virtually impossible to weld.
Taking all these points into consideration, the decision to re-body becomes an easy one. However, there are some things that you should be on the look out for when you choose a shop and commence work. First, insist that the individual blanks, which are cut and shaped to make up a completed fender, are as close as possible to the size and shape originally used. This guarantees that the seams are placed where the original coachbuilder had intended, and goes a long way towards assuring that the fender or roof section has the shape it was originally planned to have. Second, make sure all the proper fasteners are used. Never use a pop-rivet where a screw was or a solid rivet in place of a screw. Third and most important, never ever tig weld body panels! If the shop insists on this method of welding, they do not have the experience or know-how to fabricate an aluminum body. Insist that you want the panels flame welded- end of discussion.
Now for the few notably exceptions. If you're the proud owner of a '59 Ferrari Tessta Rossa with a Fantuzzi body or a '36 Delahaye done by Fagoni And Folaschi you would not want to re-body unless the original is burned or battered beyond recognition or the body is missing altogether. These are cases where the notoriety and artistry of the original coachbuilders met or exceeded that of the manufacturer and should be preserved at all cost.