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Finding hidden rust

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Old Jun 13, 2014 | 05:13 PM
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Default Finding hidden rust

It has been quite a few decades since I have had a 70's car, but was amazed at the amount of rust that can be on a fiberglass car.

Looking at this photo, I see bubbles around the headlight area that should not be there.

It would appear to me, that there are some steel attachment points there that have corroded away.

Is this correct, or is there another explanation?
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Old Jun 13, 2014 | 05:42 PM
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There is a reinforcement bar under there and the rivets on it have corroded, there is a recent post where a member is repairing that problem.

You want to see rust, check out this link.
http://forums.corvetteforum.com/c3-g...-corvette.html
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Old Jun 13, 2014 | 05:49 PM
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Hi F,
PB is right the reinforcement bar under there is steel and can rust.
The neatly spaced bumps are the rivets as he also points out.
What's interesting is that the rivets are aluminum so they oxidized enough to make the bumps. Not rust as we usually think of it.
The RUST was saved for more devilish locations on the car.
Regards,
Alan
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Old Jun 13, 2014 | 05:52 PM
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Those rivets are aluminum, I believe. And, they will eventually oxidize just from being in contact with the air. About the only place in the U.S. you will find any C3's [unrestored] that don't have "lumps" on the front end is the Arizona/Nevada area or the "inland" areas of southern CA. Until those lumpy areas above the rivets actually break open or the paint begins to crack, consider them a 'badge of honor' for an intact, original car.

(You beat me to it again, Alan... )

Last edited by 7T1vette; Jun 13, 2014 at 05:54 PM.
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Old Jun 13, 2014 | 05:54 PM
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Default Is that only on chrome bumper cars?

Did GM stop using that bar or stop using rivets after a certain year?
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Old Jun 13, 2014 | 06:46 PM
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Hi Pb,
The bar continued through 82 but I think you're right about the rivets…. the way the bar was bonded to the surround must have changed because I don't think the rivets continued to be a problem as the cars aged.
Regards,
Alan
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Old Jun 13, 2014 | 07:07 PM
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Originally Posted by Alan 71
Hi Pb,
The bar continued through 82 but I think you're right about the rivets…. the way the bar was bonded to the surround must have changed because I don't think the rivets continued to be a problem as the cars aged.
Regards,
Alan
This is heresy! How dare GM change something. Wait until the Ncrs..err...Nscr hears about this...100 point deduction!

But seriously...as a rookie I am still amazed how the simplest things that were done to increase profit are not supposed to be improved by car owners nearly 50 years after the fact (poor Rvzio is learning the art of Overspray as we speak).....but I'll get over it.


EDIT: OOOOOOOOOOOPS......back to the rust................

Last edited by doorgunner; Jun 13, 2014 at 07:10 PM.
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Old Jun 13, 2014 | 07:13 PM
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Hi dg,
I wouldn't think any change in the headlight reinforcement bar, or it's method of bonding to the hood surround, would have had anything to do with increasing profits.
Regards,
Alan
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Old Jun 13, 2014 | 07:50 PM
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Originally Posted by Alan 71
Hi dg,
I wouldn't think any change in the headlight reinforcement bar, or it's method of bonding to the hood surround, would have had anything to do with increasing profits.
Regards,
Alan
I was just picking Alan.....while I have your attention---thanks again for all the great advice on this Forum!
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Old Jun 14, 2014 | 08:48 AM
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Originally Posted by Peterbuilt
...Did GM stop using that bar or stop using rivets after a certain year?...
Bar, no. All C3s have it. Rivets, yes. Early cars have a fiberglass bonding strip riveted to the headlight reinforcement bar which was then bonded to the hood surround. With age, the aluminum rivets undergo a galvanic reaction which makes them pull away from the steel reinforcement. Hence the bumps in the hood surround in the pic.

As adhesive technology advanced, the aluminum rivets were no longer needed and were discontinued. Later cars have no rivets.

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Old Jun 15, 2014 | 11:26 AM
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Originally Posted by Easy Mike
Bar, no. All C3s have it. Rivets, yes. Early cars have a fiberglass bonding strip riveted to the headlight reinforcement bar which was then bonded to the hood surround. With age, the aluminum rivets undergo a galvanic reaction which makes them pull away from the steel reinforcement. Hence the bumps in the hood surround in the pic.

As adhesive technology advanced, the aluminum rivets were no longer needed and were discontinued. Later cars have no rivets.

Thanks for the explanation, I don't think my 74 has any rivets.
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