How Did You Repair The Nose Bumps On Your '68 to '72?

[Roger D.]

In continuing the restoration of my '72 coupe, all the trim, weatherstripping, etc have been removed and I am ready for the process of fiberglass stress crack repairs and painting. My car also suffers from the classic issue of having raised fiberglass above the two rows of rivet heads that cross the surround between the headlights and hood opening. I've read a number of posts on this and other forums regarding various repair methods but no one has specifically mentioned the outcome/condition of the repair a year or more afterwards, i.e., how is it holding up?

For those who have tackled this issue in the past I'd really appreciate a few responses on the method you used to perform the repair, how long ago you performed it and how it is holding up.

Thanks a lot in advance?

Regards
Roger

[Michael G.]

Re: How Did You Repair The Nose Bumps On Your '68 to '72?

Roger,

I've heard this condition called many different things but never 'nose bumps'. I do believe going forward this has to be the new name for this condition....it's great. Others will chime in but in the end believe the header bar will have to come out to correct this condition.

[Joe L.]

Re: How Did You Repair The Nose Bumps On Your '68 to '72?

In continuing the restoration of my '72 coupe, all the trim, weatherstripping, etc have been removed and I am ready for the process of fiberglass stress crack repairs and painting. My car also suffers from the classic issue of having raised fiberglass above the two rows of rivet heads that cross the surround between the headlights and hood opening. I've read a number of posts on this and other forums regarding various repair methods but no one has specifically mentioned the outcome/condition of the repair a year or more afterwards, i.e., how is it holding up?

For those who have tackled this issue in the past I'd really appreciate a few responses on the method you used to perform the repair, how long ago you performed it and how it is holding up.

Thanks a lot in advance?

Regards
Roger

Roger------


This condition is caused by corrosion of the aluminum rivets which retain the header reinforcement bar to the surround. It's especially prevalent in cars that have lived at least part of their life in a corrosive environment (e.g. winter salted roads).

Repairing it is quite involved. Many years ago Ralph Eckler wrote an absolutely excellent and comprehensive article on this repair which was published in Vette Magazine, for which he was a contributing editor at the time. I have that edition around here but I'd have to go through a lot of Vette magazines to find it and I have not the time or inclination right now. When I do, I'll make it available. I don't know if posting it here might infringe on some copyright laws.

[Phil D.]

Re: How Did You Repair The Nose Bumps On Your '68 to '72?

Even after the header bar is out, there's a number of different ways to do it. Method (A) involves also separating the bonding strip, re-riveting and reinstalling exactly as original. Another (B) involves installing a newer style header bar that is designed to glue in without rivets (which would not appear correct). Another (C) involves leaving the bonding strip in place, removing all the remains of the rivets from below by grinding into the bonding strip without damaging the outer panel, then gluing the header bar back in with special epoxy suited for bonding metal to fiberglass. We're leaning toward method (C), putting rivets back directly into the header bar purely for appearance before gluing it back in place as there would then be a space the thickness of the bonding strip in which they could expand. But still questions remain about how to deal with the "memory" of the outer fiberglass panel and how many years it may hold its memory. Some say the dimples largely disappear on their own over time once the rivets are gone, some suggest a little heat and clamping will flatten them out, but is it ever appropriate to block sand the dimples away? Would that ultimately lead to a divot instead of a dimple?

[Joe L.]

Re: How Did You Repair The Nose Bumps On Your '68 to '72?

Even after the header bar is out, there's a number of different ways to do it. Method (A) involves also separating the bonding strip, re-riveting and reinstalling exactly as original. Another (B) involves installing a newer style header bar that is designed to glue in without rivets (which would not appear correct). Another (C) involves leaving the bonding strip in place, removing all the remains of the rivets from below by grinding into the bonding strip without damaging the outer panel, then gluing the header bar back in with special epoxy suited for bonding metal to fiberglass. We're leaning toward method (C), putting rivets back directly into the header bar purely for appearance before gluing it back in place as there would then be a space the thickness of the bonding strip in which they could expand. But still questions remain about how to deal with the "memory" of the outer fiberglass panel and how many years it may hold its memory. Some say the dimples largely disappear on their own over time once the rivets are gone, some suggest a little heat and clamping will flatten them out, but is it ever appropriate to block sand the dimples away? Would that ultimately lead to a divot instead of a dimple?

Phil-------


The "bumps" will not disappear, immediately or eventually, once the header bar is replaced and the rivets removed. The bumps are created by the aluminum oxide which has a greater volume than the aluminum metal it replaced. So, as the aluminum metal is converted to oxide, it needs more space.

[Mark E.]

Re: How Did You Repair The Nose Bumps On Your '68 to '72?

What are we trying to fix? Aren't minor "nose bumps" something we look for on original cars, just like sunken bonding seams on fenders and quarters?

Or are we talking about a condition worse than undulations in the fiberglass that show up in the right light?

[Phil D.]

Re: How Did You Repair The Nose Bumps On Your '68 to '72?

What are we trying to fix? Aren't minor "nose bumps" something we look for on original cars, just like sunken bonding seams on fenders and quarters?

Or are we talking about a condition worse than undulations in the fiberglass that show up in the right light?

I realize there are extremes of opinion about appropriate level of restoration from don't touch anything no matter how hideous it looks to fix every little flaw and make it far better than new. My brother and I both tend to fall to the right of center as much our meager budgets will allow. But the header bar is in pretty poor shape and needed to come out anyway for rustoration.

[Russ S.]

Re: How Did You Repair The Nose Bumps On Your '68 to '72?

I believe the best way to repair is remove the header bar and as mentioned drill or grind (preferably a die grinder) the rivet head out leaving the end of the expanded pop rivet in place in the header bar. Then use bonding adhesive after roughing up both surfaces to bond the f/g strip back to the bar.What I would do to get rid of the "bumps" is when bonding the header bar back into the front end fiberglass, use C clamps and put one on each bump to press them back out and bond them in that position. Don't over tighten the C clamps or you will have a reverse bump-dimple.

[Patrick B.]

Re: How Did You Repair The Nose Bumps On Your '68 to '72?

Russ -- Is it possible to remove the header bar without damaging the paint and exterior fiberglass above the header bar.

[Russ S.]

Re: How Did You Repair The Nose Bumps On Your '68 to '72?

Yes it is possible if you go slow and easy with wide putty knives to help spread out the pressure on the painted panel. You may want to use a number of putty knives so as to get more spreading pressure spread out over a larger area. You can also heat the header panel and therefore also the bonding strip to appox. 250 degrees but if you are going to do that I would use wet towels on the painted surface in order to keep the temp down on the paint. You could also use silver sticky backed heat resistant tape and stick it to the underside of the painted panel to help keep the heat off the paint. I have used a good heat gun to do this. The heat causes the bonding adhesive to let loose.

Russ -- Is it possible to remove the header bar without damaging the paint and exterior fiberglass above the header bar.

[Phil D.]

Re: How Did You Repair The Nose Bumps On Your '68 to '72?

I believe the best way to repair is remove the header bar and as mentioned drill or grind (preferably a die grinder) the rivet head out leaving the end of the expanded pop rivet in place in the header bar. Then use bonding adhesive after roughing up both surfaces to bond the f/g strip back to the bar.What I would do to get rid of the "bumps" is when bonding the header bar back into the front end fiberglass, use C clamps and put one on each bump to press them back out and bond them in that position. Don't over tighten the C clamps or you will have a reverse bump-dimple.

That's an interesting idea. I'd have to buy several of those crazy deep c-clamps but I'm sure a wide, flat plank of wood over each dimple ought to serve to keep from over-doing it and indeed, each dimple would essentially be glued back down wouldn't they. What adhesive(s) did you use? Body shop was warning me that they've seen issues with some types of adhesives ostensibly sold specifically for the use bonding fiberglass to metal that seeped through and caused paint problems.

[Roger D.]

Re: How Did You Repair The Nose Bumps On Your '68 to '72?

But still questions remain about how to deal with the "memory" of the outer fiberglass panel and how many years it may hold its memory. Some say the dimples largely disappear on their own over time once the rivets are gone, some suggest a little heat and clamping will flatten them out, but is it ever appropriate to block sand the dimples away? Would that ultimately lead to a divot instead of a dimple?

Thanks for all the input so far. Does anyone have any additional thoughts regarding what to do with the remaining dimples? Of course we'd like a smooth surface to repaint and for it to stay that way long afterwards. Has anyone dealt with this issue before? If so, please advise.

Regards,
Roger

[Russ S.]

Re: How Did You Repair The Nose Bumps On Your '68 to '72?

Phil, I think a person might want to put a 5/8-3/4 inch round sticky like those dots you can buy for pricing items over each raised spot to be sure that they get pressed flat. You could also use vise grip long C clamps. The adhesive I use is a black(as original) product called APF 7 Black Premium quick set Polyester filler. It is made by Axson Technologies reference number F011034 out of Eaton Rapids MI phone 517-663-8191. I love this stuff.

That's an interesting idea. I'd have to buy several of those crazy deep c-clamps but I'm sure a wide, flat plank of wood over each dimple ought to serve to keep from over-doing it and indeed, each dimple would essentially be glued back down wouldn't they. What adhesive(s) did you use? Body shop was warning me that they've seen issues with some types of adhesives ostensibly sold specifically for the use bonding fiberglass to metal that seeped through and caused paint problems.

[Phil D.]

Re: How Did You Repair The Nose Bumps On Your '68 to '72?

Phil, I think a person might want to put a 5/8-3/4 inch round sticky like those dots you can buy for pricing items over each raised spot to be sure that they get pressed flat. You could also use vise grip long C clamps. The adhesive I use is a black(as original) product called APF 7 Black Premium quick set Polyester filler. It is made by Axson Technologies reference number F011034 out of Eaton Rapids MI phone 517-663-8191. I love this stuff.

Thanks. Here's a link to the technical data sheet. Seems like a pretty short pot life though as I work rather slow and there's a lot of surface to cover and a bunch of dimples to clamp. How much working time do I have with this product?

http://www.axson-technologies.com/sites/default/files/apf7-gb.pdf

[Russ S.]

Re: How Did You Repair The Nose Bumps On Your '68 to '72?

Lots of working time. It depends on how much hardener you use. I often speed it up after I am through bonding with heat.

Thanks. Here's a link to the technical data sheet. Seems like a pretty short pot life though as I work rather slow and there's a lot of surface to cover and a bunch of dimples to clamp. How much working time do I have with this product?
http://www.axson-technologies.com/si...es/apf7-gb.pdf