rivet bumps on hood of car

[lizzard71]

I am shopping for a 68-72. If a car does not have these bumps (and has old or original paint), can a person be confident they won't appear in the future? Or is it always a risk?

 

[norms72]

My 76 the headerbar was so rusty it was not fastened to the fiberglass and had no rivot pops
So any info on this repair will be of future use to me.

I think starting with the '73's the rivets weren't used, but the pro's here might chime in to verify this.

I've got the bumps so this repair will be in my future as well.

 

[6880 Mike]

The aluminum rivets were used to hold the header bar (steel) to the bonding strip. The bonding strip was, in turn, bonded to the under surface of the upper surround panel. Over time, there is a reaction between the aluminum and the steel which causes the rivets to back out and up through the fiberglass of the surround panel.

Once you can see the rivet heads in the fiberglass, they will not go away on their own.

 

[Crimson Thunder]

I know this will be hard to answer, but what is the cost involved in a repair like this.Would it be cheaper to just buy a new one piece front end(assuming its a non original car that it wouldn't hurt the value of the car)

 

[Willcox Inc.]

No, I would not replace the front end of the car… This problem is very fixable. Evidently I’m not the only one that thinks the bar should be removed to repair this issue. Check out the link on Dr. Rebuilds Page. http://www.docrebuild.com/dr-r-web/tip18.html

 

[spongebob46]

No, I would not replace the front end of the car… This problem is very fixable. Evidently I’m not the only one that thinks the bar should be removed to repair this issue. Check out the link on Dr. Rebuilds Page. http://www.docrebuild.com/dr-r-web/tip18.html

I agree. I just removed the header bar on my 72. It is really not that hard to do. My body is sitting on a dolly so access was easy. To remove the header bar use a sharp carpenters chisel. It will slice off the aluminum rivets flush with the header bar and it will almost drop off on it's own. After the header bar is off use a heat gun set on high to soften the adhesive on the bonding strip. As the adhesive softens use a putty knife to slide between the bonding strip and the surround to break loose the bonding strip. Do not pry or twist on the putty knife - let the heat do the work. As you are heating the bonding strip check the outer surface of the surround with your hand. If it is too hot to lay your hand on remove the heat from that area for a few seconds and heat on ahead of the area you are working on. Above all, be patient and don't overheat the surround. I removed the complete bondind strip in about an hour. The bonding strip is in good enough condition I am going to reuse it with new rivets. If you are doing this job with the body on the frame I think it would require the removal of the hood, radiator, and headlight buckets.

 

[iron cross]

I thought by now this would go away. IN MOST INSTANCES YOU DO NOT HAVE TO REMOVE THE HEADER. That is unless you want to make a lot of work for your self or justify charging an enormous price to repair it. :L What does a luggage rack have to do with nose bumps? If you cant repair fiberglass you shouldn`t take the job. We have repairs and modifications in Vettes, boats, and race car bodies over 30 years old and are still as good as new. You dont get the "Riddler Award" for turning out garbage.

 

[Evolution1980]

OK...it seems that we've more or less got the 1972 rivet issue cleared up as much as it's going to be. So let me not-so-subtley hijack this thread somewhat.

Norms72 said that he believes that they stopped using the rivets after '73.

Soooo...what about my 1980 where the fiberglass has broken free from that support bar (or whatever it is?) I'm a weeee bit PO'd because it's right behind the headlight door and because of that, the headlight going up and down chipped the paint on the body because it kept catching. What is the process for doing a repair like this on an '80, i.e., getting the fibergalss attached back to the support or whatever?

 

[Willcox Inc.]

All cars from 1968-1982 had the rivets. The bonding may have pulled loose, but there can be other reasons headlamp door drag problems. If the bonding is loose, you can repair this pretty easy, but you might want to look real close for the cause of the loose bonding.

Moving headlamp doors can be caused by several issues! The biggest disappointment is to paint your car only to raise the lamps and chip the paint. In most cases the failure is related to lack of proper repaired when the cars are painted and in the long run it will bite you in the rear.

Corrosion between the headlamp support and the header bar (LOCATION (A) IN DIAGRAM) will also cause the headlamp door to move when opened and closed! Look under the car at the header where the headlamp support is bolted down to the header bar. If you see swelling in the support where it bolts to the header, then you have an issue. If swelling is present, then you should remove support and access the damage before you proceed.

Check the ends of the headlamp supports where it bolts to the front metal support on the car. It is common for the ends to be broke off! Inexperienced body shops will try everything to keep from replacing these even if the ends are broken off. Broke ends will cause the headlamp bucket to move. (Location B in diagram).

If you have a headlamp door that is rubbing the outer surround panel I would check these things. I would not put so much emphasis in #3 but they should always be replaced or inspected before you paint any car with a lid that is moving.

1) Headlamp support pivot bushings #36 in picture.
2) Headlamp support corrosion to the header bar. (A) In picture.
3) Bushing wear in the headlamp actuator linkage bushings. 45, 48, 49, 54, 57, 58
4) Headlamp end support broken off due to prior repair! (B) In picture.

Good Luck,

 

[Evolution1980]

If you have a headlamp door that is rubbing the outer surround panel I would check these things...

Yeah, that's my problem. The headlight panel is fine. It's the portion of the body directly between the hood and headlight door. I can push down on the body there and see the flex / unattached area.

 

[Tominator]

Header Panel Bumps

Thank you for all the great comments posted here. They helped me start a repair job I was not looking forward to. Managed to get the metal support bar/bonding strip out even though both seams were still solidly bonded to underside of header panel. The bonding strip will be reusable with a bit of sanding to remove old bonding material and allow a fresh mating surface. Metal support bar will need sand blast and epoxy prime also.

 

[Evolution1980]

Thank you for all the great comments posted here. They helped me start a repair job I was not looking forward to.

All part of our friendly service! And thank you for using the "search" function of the site (if that's what you did) Good job!

How did you come across a three year old thread?

 

[paz72vette]

Great Write Up

I this one task I am also not looking forward to. Thanks for the pictures.

Cheers

Vito

 

[VetteV8]

Thanks for the pictures!
They clarified the problem a lot better than the 2 pages of text before; at least for someone like me, who is not familiar with this problem/defect.
All clear now.
Thanks again.
Cor

 

[6880 Mike]

...The header does NOT need to be removed in most cases, nor the headlights, brackets, ect. However the rivets must be removed...

Hmmm. I am wondering whether you have actually made this repair. Without drilling through the hood surround panel and making more work than you need to, how did you get the rivits out without removing the bar?

 

[2VettesMike]

Tominator, thanks much for the great photos. I have had the "rivet bumps" on my 72 since I bought it 23 years ago, they are the same as they were then and I consider them beauty marks of originality.

BTW, over 4 years between posts 30 and 31. If not a record a fine average between posts on a dormant topic...

Thanks again,

Mike

 

[Tominator]

Evolution 1980
I typed "hood bumps 71 corvette" into GOOGLE and this thread came up - These posts may have started over 4 years ago but I didn't even know this car existed then so it was nice to have found this very informative site now that the repairs are under way. Thanks again for such a fine site.

paz72vette + VetteV8
Glad you like the photos

2VettesMike
I can appreciate your take on the rivet bumps. But as the saying goes "Beauty is in the eye of the beholder" and the owner of the car has a different definition.

 

[SolidLifters]

I'm kinda' surprised at Wilcox's comment on the previous page "all cars 68 through 82 had the rivets. This is untrue. Sometime after 1970 they started bonding the header bar directlly to the surround without the bonding strips OR the rivets. I'm not sure what year the change was made 'cause I've never been interested much in anything newer than 70, or truthfully 1969.

One other thing we've got going for us now is superior bonding adhesives. I never can remember the number, but one of the two part 3M's that is shot from the gun through a mixing tube will hold a bare header bar to the surround better than either method the factory used from '69 foward.

As an alternative to the method of pulling the bar, which I would think removing and reinstalling in exactly the right place would be nighmarish on a car that's complete, seeing as how it'd take removing the hood, headlights, and preferably the radiator and core support. I've done several 69's that have lastted a long time by cutting holes in the glass down to the rivets (I actually did slots with a die grinder instead of round holes with a holesaw, sanding the tops of the rivets, covering them THICK with Zinc Chromate, then glassing and finishing. I usta' use the Fiberglass Evercoat brand of panel adhesive as filler over the glass, but more recently use the panel adhesive that Corvette Image sells in the can that is as close to the old factory glue as anything I know of on the market. As a side note, I don't know how that stuff works.............. when used as a filler it'll feel sticky still even if allowed to dry overnight, but light sanding firms it right up, and I haven't seen any shrinkage with it at all.

I read an article by RAlph Eckler many years ago in which he stated that panel strip adhesive should never be used as filler and that he always skimmed over repairs with regular old polyester filler like Bondo. I've just never liked putting Bondo type materials on a fiberglass car, and I've never had shrinkage and other issues over the years that I've seen on cars with Bondo type materials.

Anyway, fixing from the top has always been adequate for me and they've made it through multiple Bloomington Gold and NCRS Top Flight awards.

 

[SVO]

1972 was the last year for the riveted header bar. With the change in 1973 to SMC body panels, the header bars were bonded in. With the change in panel material, bonding adhesive changed from a polyester based material to an epoxy based material. The epoxy bonding adhesive is superior to the older material used.

 

[paz72vette]

Tominator,

I was under the nose this past weekend. I got to wondering how you fit into the area to work. Did you make a raised platform? Are you shorter then 4"11"? Did you also take both the bar and bonding strip out same time? If it is not too much to ask, can you do a write up and post or send me a PM.

Many thanks

Cheers

Vito