Carbon Fibre reinforcement

[Ian K]

Hey all,

I was checking out the GT40s restored at the
following site:
http://www.grandsportcorvette.com/gt/1076.htm

I am seriously interested (when the time comes)
in also using carbon fibre tow dipped in epoxy,
fixed to strategic locations on the body's
underside for reinforcement and better
shape memory. Anybody try this yet?

Ian

[ March 20, 2003: Message edited by: Ian K ]

 

[Jim Rosenthal]

Ian, I think this is a really interesting idea. All of the vintage GT40s I have seen, which only number three, had plenty of cracks in the fiberglass bodywork. Mind you, they are forty years old, nearly....
The newer cars I have seen (two Safirs and two ERAs), did not have stress cracks. I don't know whether they were laid up to a stronger laminate schedule, whether better resin was used, different glass, or whether they too will have cracks when they are forty years old.
In any case- what I would look at, if I wanted to do this, is carbon fiber tape from West System/Gougeon Brothers, and secure it with epoxy. Polyester bonds poorly to cured polyester laminate, but epoxy will hold.
When I order the body for my car, I asked for extra layers of knitted cloth, (not chopped mat or woven roving) to be glassed into the inside of the body parts, to achieve better shape retention and hopefully avoid stress cracking. It cost some weight, however. When I compared them with identical sections made from the same molds, but in carbon, the difference was dramatic. As my car will be used chiefly on the street and only occasionally on the track, assuming I am good enough to drive it there, I felt the extra weight was worth it. Good luck. Post your results when you have some...

 

Ian, When you layup carbon tow on or in the under side of a glass layup, will get " print through " to the outer side with age. You will see this grid pattern all over the body. I had a Chevron B16 body that had this done. They layed carbon tow on the inside of the body in a grid pattern forming six inch squares. You see this 'print through' problem often when a honeycomb core is used with thin facings. The carbon tow stiffening ribs seemed to be a good
idea at that time, but composites have progressed quite a bit from the seventies.

 

[Mark Worthington]

While installing my body clasps this past weekend I noticed that my sill covers showed telltale evidence of stress cracks from the car these molds were originally taken from (my sill covers are fine, they just show what the previous car looked like). Accordingly, I've decided to use some carbon fiber fabric to reinforce the underside of the attachment points on the top of the sill covers where the body clasps and body-locating cones mount.