C3 body stress cracks

[Greg L.]

I have some stress cracks around the headlight openings and hood inserts on my 69 and was wondering if someone could suggest the best way to repair these cracks. I have the areas stripped down to the bare glass and it seems to be cracked only on the surface. Is sanding the area down and then applying fiberglass resin without the mat an acceptable fix? Thanks for any help on this one.

[Craig S.]

Re: C3 body stress cracks

Greg - this is a common area to get stress cracks. Personally, I would vee out the cracks, and use matt and resin, or, use a good grade of bonding adhesive/filler. I suspect if you just you resin as a gel application in a stress area such as this, it will come back again....Craig

[Larry S.]

Re: C3 body stress cracks

I am not a body man but when my car was re done I had simular cracks and the body shop drilled a tiny hole into the end of the crack ( I was told that the hole would NEVER allow the crack if it returned to move past the drilled hole)they then veed out the crack and used resin and matting to repair it.They have not returned since.I had some cracks just behind my door handels That repair I was not around to see how they fixed but a short time latter they have returned

[Wayne W.]

Re: C3 body stress cracks

Hum, The old drill a hole in the end of the crack method. Interesting, but useless. May even cause more problems than it solves. This is an old urban legend that the crack is going to run, like glass on a windshield. It just aint so. Dont do it.

[Larry S.]

Re: C3 body stress cracks

Thank You wayne for bringing me up speed on the hole in the crack information.When it was exspained to me it made perfect sence.

[Scott Marzahl]

Stop Drilling

Stop drilling a crack in aluminum is common practice in the airline industry, but I can't say if it works with composites.

[Tracy C.]

[Greg L.]

Re: C3 body stress cracks

Thanks guys! I think I'll prep the cracks like Tracy says but use the fiberglass and matt like Craig says. I'll leave the stop drilling to the aircraft structures guys.

[Klaus Friedrich]

Re: C3 body stress cracks

Hi Greg,

I did a frame off restauration of my 69 in 1998. I've found many stress cracks in the composite of the complete front end after grinding. A professional body shop with experience in Corvettes fixed them.
But now, after 5 years they came back - all!
I think the composite material gets older and brittle.
Next year I'll repair the complete frontend again ... and again and ...

Klaus Friedrich
Germany

[Greg L.]

Re: C3 body stress cracks

Thanks for the input Klaus. Do you know if the cracks are the old ones that came back or are they new cracks,but in the same general area?