1963 Porsche 904 GTS Prototype

The fiberglass-to-metal body and chassis bonding worked fine for the projected race life of a 904, then rust began to separate the two elements

by Jim Schrager

With the proven 356 Carrera Abarth having served formidably for three seasons, the imminent arrival of the two-liter Simca Abarth meant that Porsche was going to have to raise the stakes for 1964.

Early in 1963 Ferry Porsche’s son, “Butzi,” finished a full size model of the new design. Although used already on the body panels of their Grand Prix car, this was the first time Porsche planned to use fiberglass on a sports car. In typical Porsche fashion, this new material was put to additional use on the 904 and it increased torsional rigidity by bonding the fiberglass to the steel ladder-frame chassis.

Not only was the fiberglass body to benefit structurally and in weight savings, but it was cost-effective as well. Rather than undertaking this aspect in-house, the fiberglass bodies were subcontracted to Henkel, an aircraft parts supplier.

The new design was a low-slung, slippery two-seater, and using all of their experience, Porsche created...