Question about 71'
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2nd Gear
Joined: Dec 2012
Posts: 2
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Question about 71'
I've noticed pictures of early 70's late 60's with mysterious "bumps" above the front head lights in the fiberglass. The reason I ask is My father passed down a 71' driver that's in great shape with these same "bumps" in the fiberglass. I would say 6 or 7 across the top of the each light. What are they from....I remember displaying the car with him at shows when I was a kid and they weren't there then. Just wondering......
Le Mans Master
Joined: Jan 2006
Posts: 8,246
Likes: 114
From: Watkins Glen NY
They are from deteriorating rivets on the header bar.
The header bar is a metal support which runs from side to side and has a bonding strip riveted to it. The nose then glues to header bar/ bonding strip. Over time the aluminum rivets corrode due to contact with the steel header and expand. The end result is the series of round spots that you see.
Often this is evidence that the front end hasn't been hit, replaced, or repainted or otherwise screwed with.
The header bar is a metal support which runs from side to side and has a bonding strip riveted to it. The nose then glues to header bar/ bonding strip. Over time the aluminum rivets corrode due to contact with the steel header and expand. The end result is the series of round spots that you see.
Often this is evidence that the front end hasn't been hit, replaced, or repainted or otherwise screwed with.
Safety Car
Joined: Sep 1999
Posts: 4,930
Likes: 11
From: AnyTown NJ
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
It is an issue with the chrome bumper C3s. The reinforcing bar that the headlamps hang from is two pieces of steel fastened together with aluminum rivets. One of those pieces of steel is bonded to the underside of the hood surround.
The problem is the aluminum rivets corrode when moisture (even humidty in the air) reacts with the aluminum and steel pushing the paint up into a bump/bubble. All remnants of the aluminum have to be removed to prevent the reoccurrence of the corrosion.
The best fix is to remove the steel reinforcement, remove all of the aluminum rivets, then rebond the upper reinforcement bar to the fiberglass and glue/epoxy the two pieces of steel together, then repair the fiberglass.....not an easy task
Another method used is to grind out the rivets and fill with glass but with that type of repair the results over time are mixed.
You can also just leave them alone as it's a sign of an original front clip/paint.
The problem is the aluminum rivets corrode when moisture (even humidty in the air) reacts with the aluminum and steel pushing the paint up into a bump/bubble. All remnants of the aluminum have to be removed to prevent the reoccurrence of the corrosion.
The best fix is to remove the steel reinforcement, remove all of the aluminum rivets, then rebond the upper reinforcement bar to the fiberglass and glue/epoxy the two pieces of steel together, then repair the fiberglass.....not an easy task
Another method used is to grind out the rivets and fill with glass but with that type of repair the results over time are mixed.
You can also just leave them alone as it's a sign of an original front clip/paint.
Race Director
Joined: Oct 2000
Posts: 12,652
Likes: 3,110
From: Shamong, NJ
Typical Corvette problem. Around the mid 70's, Chevrolet stopped using the rivets and bonded the surround reinforcement in instead.If you want to eliminate the bumps permanently, you need to remove the rivets and bond the reinforcement in.
Safety Car
Joined: Feb 2012
Posts: 4,705
Likes: 983
From: Orlando FL
I`m also new to Corvettes. We bought a 71 with front fiberglass damage. The front clip we bought from another car had the "rivet bumps". I followed the great advice of Willcox Corvette.... I ground the rivet heads off, pulled the steel header off, then dug out the remaining pieces of the rivets. Then I glued the header back on, with extra glue into the holes left by the missing rivets, and a board with a bunch of clamps. The board acts to push the fiberglass bumps back down.
Last edited by oldgto; Dec 28, 2012 at 05:48 AM.
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Safety Car
Joined: Feb 2012
Posts: 4,705
Likes: 983
From: Orlando FL
I dug my rivets out from the bottom, so there was no surface damage to repair.
Before.....
And after.....
Last edited by oldgto; Dec 28, 2012 at 05:19 PM.