Posted 02 September 2003 - 09:30
Yes, I've always understood the coloured discs were to denote the body material. Yellow was used for aluminium and red for fibreglass - not sure about other materials, I'm afraid. What I'm also not so sure about is what was done for cars with more than one body material - e.g. my own ex-Le Mans car, which ran in 1962 and has a mainly aluminium body wore a yellow disc, but parts of the shell were steel. Maybe they thought they didn't need to differentiate between steel and aluminium, given that the main purpose was for fire-fighting decisions? That said, one of the Lola Astons which ran in 1967 - the one with the more stremlined rear - carried a red disc on the front body section but a yellow one on the (presumably aluminium) tail, yet I know of other part metal, part fibreglass bodied cars which carried only the yellow disc. Not sure how long this requirement (or practice) lasted, but it seemed to apply during the early to mid 'sixties.
Another related question - during the 'fifties, a number of cars at Le Mans wore red, white and blue discs on their flanks. I think I read somewhere that these were carried by cars competing for the triennial cup - can anyone confirm or otherwise?