Fellow Members: I recently saw a mid-year car that was restored about 12 or so years ago and only driven but a few miles since (or so I was told) and I was surprised to see several stress cracks in the body/paint, about 1/2 inch or so long. What would cause this to happen?? Was something done incorrectly in the restoration? Is the car not sitting correctly on the frame? What could be done during a restoration to prevent such an occurrence in the future? Is this an issue for all years? Thanks for any ideas... Tony (trying to learn more about why this happens???)
Body/paint stress cracks (mid year cars)
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Re: Body/paint stress cracks (mid year cars)
It happens because its a Corvette and not a Desoto. That may be a little over the top but its true that it really is the nature of the beast. These cars are like living beings. They move they settle they breath. You have a vehicle that was constructed of dozens of different panels with sever angels and high pressure stress points, movement is inevitable. With that movement comes cracking. The glass can flex quite a bit without damage but that's not necessarily true of the paint, so while the body can move back and forth the paint is not as ply-able.To some extent this can be minimized by making sure all attachments are in good shape with proper shims in place and secure and that all cross members and braces are not missing or rusted out. But even if everything was perfect as when new all you have to do is drive over one washboard road and that car can flex enough to torque it to pieces. I like to think of it as being part of the cars charm.- Top
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Re: Body/paint stress cracks (mid year cars)
Tony:
Kenny's right about the movement. Glass Reinforced Plastic (GRP) is dimensionally unstable. It moves a lot with temperature changes, and it also flexes easily. There is also a lot of vibration in any car. I'm always surprised that the paint can keep up with it.
The cracks that you saw were either reflections from cracks that were not properly repaired during the body prep, or are newly formed. Either way, they come from stress points in the glass due to temperature, improperly aligned braces and attachment points, or vibration.
Paul- Top
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Re: Body/paint stress cracks (mid year cars)
Paul, would these cracks as you describle likely just continue to grow over time or reach a natural stopping point? Or maybe either one could happen depending on the individual factors of the car? Thx Tony
P.S. very good answers to this post!- Top
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Re: Body/paint stress cracks (mid year cars)
A month ago, to my horror, I found what turned out to be a fiberglass stress crack on my front fender. I first thought someone had scratched my perfect paint job.
It cost me $600 to have a Corvette restorer fix it. They had to repaint the entire fender inboard of the peak, from the headlight bucket to the windshield. I have attached a photo of the area being repaired.
The shop owner told me that there is nothing that you can do to prevent this sort of damage. It happens all the time with vintage Corvettes and is due to body flex on aging fiberglass.
-ClarkAttached Files- Top
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Re: Body/paint stress cracks (mid year cars)
Yes, an EXCELLENT tutorial! Also, remember quite a few of these low mileage restored cars were hauled to this/that judging meet. While most haul in an enclosed trailer, the car STILL moves on its own suspension while it's on the road...
My '65 has only +500 miles on the clock, but it saw something like 15000 miles being trailered to various events during its award campaign... And, YES, it now has minor stress cracks in the 'typical' places the car was known to have developed them when factory new and driven/used by the original owner!- Top
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Re: Body/paint stress cracks (mid year cars)
They appear to reach a natural stopping point. I assume that once the crack is at the edge of the high stress area it stops. In addition, the fibers reinforce the GRP and retard the crack.- Top
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