'72 Grilles

[Roger D.]

Took the grille pieces off my '72 for restoration as the previous Owner had painted them black. A couple of questions:

1. I understand that the grilles are not made of pot metal but are aluminum. Anyone had experience in fixing a crack in one of these? I have a crack on the upper right side of the right grille.

2. My '72 car has a September '71 build date. My left grille does not have the fiber optic connector but my right one does. Any chance that they had leftovers from previous years with fiberoptics and used one on my early build '72?

Thank you.
Roger Dupler

[Terry M.]

Re: '72 Grilles

1) I thought the "pot metal" used for these kinds of castings is primarily zinc. I think aluminum would be more expensive than necessary for these parts. Finding someone to fix them, unless something like epoxy glue, or JB Weld is used, will be a challenge. On the other hand folks with really old cars have to cross the bridge also, so see what information comes up here and in the pages of Hemmings.

2) Could be for your early car they used the remaining stock of 1971 parts, but you will meet skeptical judges since the long available SERVICE part was the 1971 style with the hole for fiber optics.

[Joe L.]

Re: '72 Grilles

1) I thought the "pot metal" used for these kinds of castings is primarily zinc. I think aluminum would be more expensive than necessary for these parts. Finding someone to fix them, unless something like epoxy glue, or JB Weld is used, will be a challenge. On the other hand folks with really old cars have to cross the bridge also, so see what information comes up here and in the pages of Hemmings.

2) Could be for your early car they used the remaining stock of 1971 parts, but you will meet skeptical judges since the long available SERVICE part was the 1971 style with the hole for fiber optics.

Terry and Roger-----

The grilles used for 1970 through 1972 were zinc diecast (i.e. "pot metal"). None were EVER aluminum. The 73-74 grilles were also zinc diecast. In fact, I think the last time that any aluminum material was used on ANY Corvette grille was for the 1965 model year, although it's possible that some late 70's grilles used some.

[Steven G.]

Re: '72 Grilles

I always considered them to be pot metal also, until i spoke with Richard Fortier and he did mention they were aluminum, unless I was half asleep, I dont really know myself, but i plan on getting him to rework a set. Steve

[Joe L.]

Re: '72 Grilles

I always considered them to be pot metal also, until i spoke with Richard Fortier and he did mention they were aluminum, unless I was half asleep, I dont really know myself, but i plan on getting him to rework a set. Steve

Steve-----


All I can say is that I'm amazed that Dick Fortier would think that these grilles were aluminum.

[Gordon H.]

Re: '72 Grilles

Had one of mine repaired and the welder said it is aluminum . He did a heliarch weld to fix it . My welder said aluminum ! After his welding I filed it to shape . He's been in the business for 35 years . Have to take the chrome off first . It can be done

[Gordon H.]

Re: '72 Grilles

If this comes out you can see the weld .Haven't uploaded pictures before .

[Joe L.]

Re: '72 Grilles

Had one of mine repaired and the welder said it is aluminum . He did a heliarch weld to fix it . My welder said aluminum ! After his welding I filed it to shape . He's been in the business for 35 years . Have to take the chrome off first . It can be done

Gordon-----


Well, it's a complete surprise to me. These things have always felt way too heavy to me to be aluminum. Plus, when I've seen them broken (usually the studs on the bottom), the "break point" looked like zinc diecast to me. But, I'll have to admit, I've never filed off any of the metal, dissolved it it acid, and analyzed it. I'll have to look closer at one the next time I come across one.

[Steven G.]

Re: '72 Grilles

Gorden, Weld + Filing work sure looks good ! Are you going to do prep work or send it for chrome and let them do that, and have you chosen a chrome shop? Thanks, Steve

[Roger D.]

Re: '72 Grilles

Fellas, I actually spoke to Richard Fortier on the phone this evening. He said he has repaired/restored a number of these and that they are indeed aluminum. He said once the crack is fixed then you have to plate the grille first with copper and then with chrome. I am still reeling over the cost to have one of these repaired and then rechromed (not even including paint which I would do myself). He sells a reproduction grille for a very reasonable price. The only thing is that all reproduction grills for 71-72 have the holes in the housing for fiber optic.

Thanks to Scott Simms for getting me in contact with Richard.

[Patrick H.]

Re: '72 Grilles

Gordon-----


Well, it's a complete surprise to me. These things have always felt way too heavy to me to be aluminum. Plus, when I've seen them broken (usually the studs on the bottom), the "break point" looked like zinc diecast to me. But, I'll have to admit, I've never filed off any of the metal, dissolved it it acid, and analyzed it. I'll have to look closer at one the next time I come across one.

The way these things corrode, they sure don't seem to "act" like aluminum. Those nice zits sure look like pot metal corrosion to me as well. And, I'd agree that they weigh a lot more than I'd expect for an aluminum part, and don't crack like one either.

I've got a broken one here that I may be able to test.
How should I attempt to differentiate the two types of metal?

Patrick

[Terry M.]

Re: '72 Grilles

If you have a reasonably small piece I would send it to the guy who identified the radiator cap finish. He has the absolute best equipment for the job.

[Patrick H.]

Re: '72 Grilles

If you have a reasonably small piece I would send it to the guy who identified the radiator cap finish. He has the absolute best equipment for the job.

Ah yes.

I'll have to check into that.

Patrick

[Joe L.]

Re: '72 Grilles

The way these things corrode, they sure don't seem to "act" like aluminum. Those nice zits sure look like pot metal corrosion to me as well. And, I'd agree that they weigh a lot more than I'd expect for an aluminum part, and don't crack like one either.

I've got a broken one here that I may be able to test.
How should I attempt to differentiate the two types of metal?

Patrick

Patrick-----


Yes, the manner in which they corrode ("zits") is something else I've observed and forgot to mention.

If I still had access to my lab at work, I could easily determine the metal. Just file off the tiniest amount, have the lab staff dissolve it in hydrochloric acid, and analyze the solution with atomic absorption spectrophotometry. I used to do this all the time to determine the metal or finish a particular part. However, that ability pretty much ended when I retired. I'll have to ask the also-retired chemist I used to work with if he can come up with any easy way to ID the metal. He's better than me in coming up with that kind of thing. You don't really need atomic absorption spectrophotometry for something like this since you're not looking for trace levels of the metal----just the predominant metal, either zinc or aluminum in this case.

[Patrick H.]

Re: '72 Grilles

Patrick-----


Yes, the manner in which they corrode ("zits") is something else I've observed and forgot to mention.

If I still had access to my lab at work, I could easily determine the metal. Just file off the tiniest amount, have the lab staff dissolve it in hydrochloric acid, and analyze the solution with atomic absorption spectrophotometry. I used to do this all the time to determine the metal or finish a particular part. However, that ability pretty much ended when I retired. I'll have to ask the also-retired chemist I used to work with if he can come up with any easy way to ID the metal. He's better than me in coming up with that kind of thing. You don't really need atomic absorption spectrophotometry for something like this since you're not looking for trace levels of the metal----just the predominant metal, either zinc or aluminum in this case.

OK.
I won't be near the grille until Thursday.

Patrick