aluminium or fiberglass (plastic)

[sanders]

Some werks rally cars used aluminium body panels. Some and/or fiberglass (plastic). Ditto road racing werks cars. Does anyone know the reasons for using one lightweight matrial over the other?

[Fixer]

I would guess cost of manufacture. It would be easier and thus cheaper [simpler] to make certain panels and shapes like the wings or ducktail in fiberglass than aluminum.

[sanders]

I was more interested in panels like hoods and doors on early cars. The 911R used fiberglass for lids, doors, fenders and bumpers. The 911GTS used aluminium. Both were werks rally cars. Cost could be the reason but I suspect it had more to do with rules.

[stretch]

It is my understanding that it was the rules. The R was run in the prototype class as GRP was not allowed in the 2.0 GR 3 class. I think the first GRP panels were used in GR 4 for the 2.3 ST cars beginning in 1970.

[sanders]

Thanks stretch. Although ST cars appear to use a combination of both alu and GRP. Any particular reason for that?

[stretch]

I think the rules specified metal body, so aluminium was allowed. GRP was then allowed in the April 70 homologation document for GR 4. I think the use of material is purely an individual choice of the race teams. An example is the Gaban Group 4 car that was the lightest 911 to compete in the 1970 Le Mans race. This was due to extensive GRP whilst most ran with steel.

[RSTarga]

I would imagine it was based on tooling costs and how many they could use in the future. GRP molds are lower cost than stamping tools, but for higher production, more labour intensive.

[uai]

I was more interested in panels like hoods and doors on early cars. The 911R used fiberglass for lids, doors, fenders and bumpers. The 911GTS used aluminium. Both were werks rally cars. Cost could be the reason but I suspect it had more to do with rules.

911r bodies were built by baur in Stuttgart not at the werk.

Cheers

Uli

[sanders]

The werks rally cars at the 1970 "Monte" appear to have the group 4 GRP kit and aluminium elsewhere. I'm am curious as to why the combination when both materials were available for all those panels. Maybe "it is what it is" but is there a reason?

[rower]

Does anyone have any of the aluminum body parts for sale? Or know where to get them?