Rivets working up through glass on nose
Prior to body-off restoration, body man, showed me bumps in the nose just below the hood line. He indicated this was from rivets working up from below. He drilled-out the holes re-filled them, new gelcoat, new paint. Approximately 2 months after new paint was applied, the bumps re-appeared. They were drilled-out again, filled with glass, new gel coat and new paint. Body man is saying other painters are indicating this problem is likely to resurface. Does anyone have experience with this condition?
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Re: Rivets working up through glass on nose
If having the bumps showing counts as experience -- then count me in. If you are looking for successful repair -- not me. Since my 1970 is mostly original paint, I am not touching them -- but if I ever decide to repaint the car (over my dead body) then I will try to have them fixed.
There have been other threads about this. It is a common 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 humidify in the air) reacts with the aluminum and steel. ALL remnants of the aluminum have to be removed to prevent the reoccurrence of the corrosion. Usually folks 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. I suppose the two pieces of steel could be welded together before rebonding.
Simply grinding out the corroded part of the rivet is not effective -- as you have found out. One has to remove everything from under the nose. It is NOT a quick or easy fix.
And now you know why I have learned to live with the bumps on my 1970.Terry -
Re: Rivets working up through glass on nose
As usual, Terry is 100% on the money.
Besides corrosion/rust, I've also heard that there is possibly some "electrochemical" reaction between the aluminum rivets and the steel header, fueled by moisture.
Chuck1963 Corvette Conv. 327/360 NCRS Top Flight
2006 Corvette Conv. Velocity Yellow NCRS Top Flight
1956 Chevy Sedan. 350/4 Speed Hot RodComment
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Re: Rivets working up through glass on nose
Craig, glad to see that you found some info on the rivets. I figured someone on the board would be more knowledgable on this subject than I.
Cheers,
CharlieComment
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Re: Rivets working up through glass on nose
There was at least one prior thread on this subject where I commented along the lines Terry echoed. It's the dissimilar metals (steel reinforcement bar + aluminum rivets) that the cause factor.
One other tip, filling the grind out holes with bond, will NOT fix the problem! Even if the aluminum rivets are completely removed, the bond is going to progressively shrink with time/age and you'll have recessed areas...
The trick is to fill the repaired areas with GLASS. That means your body man has to mix glass + resin and fill the holes with sucessive THIN layers to build up the repaired area before sanding the top surface flush/level with to the surrounding glass panel...Comment
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Re: Rivets working up through glass on nose
I can recall when I had a very early 68BB convertible (1st one in my town) that I was disappointed that in short order the nose was full of rivets showing thru. Not when the car was first purchased but after it aged a few months.Comment
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Re: Rivets working up through glass on nose
Craig,
I have the same bumps with my '68. I counted over 20 bumps on my car's nose. Because of it I will never do well on concours judging but most experienced NCRS judges know of this problem and like to see original cars. They don't hit the car with many point deductions because of it. It looks to the casual observer that the nose has been hit and bubba tried to put it back together. So the bottom line as I see it is that it looks a little strange but it an original car as far as the front is concerned.
TerryTerry Buchanan
Webmaster / Secretary - Heart of Ohio Chapter www.ncrs.org/hoo
Corvettes Owned:
1977 Coupe
1968 Convertible 427/390 (L-36) Chapter Top Flight 2007, Regional Top Flight 2010, National Top Flight 2011
2003 Electron Blue Coupe
2019 Torch Red Grand Sport CoupeComment
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Re: Rivets working up through glass on nose
Years ago there was an absolutely excellent article in Vette Magazine written by Ralph Eckler that gave a complete description, including photos, of the steps necessary to repair the front nose rivet problem. I do recall that it was quite an involved process. As a matter of fact, I have the issue containing that article in my collection of Vette Magazines. Unfortunately, I don't recall what issue it was in and I have not the time or inclination to start looking through a whole bunch of back issues.In Appreciation of John HinckleyComment
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Re: Rivets working up through glass on nose
This is one of the reasons that in 1974 they quit riveting them in. The header bar is bonded using adhesive.Dick WhittingtonComment
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Re: Rivets working up through glass on nose
1973-1974, one of them there newer cars.
Dick WhittingtonComment
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Re: Rivets working up through glass on nose
Dick,
How much trouble to remove the header bar?
Would you spot weld it together then rebond as in a 74 or is it designed differently so that it can not be bonded back in sucessfully?Comment
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Re: Rivets working up through glass on nose
Come to think of it, I don't think I've ever seen an early original C3 that didn't have the nose pimples. I expect to see them on these cars.Comment
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Re: Rivets working up through glass on nose
It is a lot of "fun" John. After removing the bar, you have to grind the fiberglass in the area that the bar is to be bonded to. To give it an authentic look, I removed the heads of new rivets and bonded the shanks in the old header bar. You need to peen the shanks so that they appear to be correctly installed. Remove any paint on the top of the header bar. I use Lord Fusor to bond the bar to the upper surround. Make you a jig to clamp the bar at least overnight. Then you can repair the holes in the panel either using fiberglass or using panel adhesive to fill themDick WhittingtonComment
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