Rear Defroster Vent Grate on 71 Convertible

[Vince L.]

Thanks,
Vince

[Joe L.]

Re: Rear Defroster Vent Grate on 71 Convertible

Thanks,
Vince

Vince------


If you are referring to the GM #3949937 grille as I expect you are, this is a piece unique to 1969-75 Corvette convertibles with C-50.

[Chuck S.]

Re: Rear Defroster Vent Grate on 71 Convertible

If I'm not mistaken, the rear grills, plus the front plenum grill and wiper door are all die cast aluminum.

You might want to check out the cost of a used grill before you go ahead. I would expect a used grill to be cheaper than having one machined from aluminum, and it would an authentic replacement.

[Vince L.]

Re: Rear Defroster Vent Grate on 71 Convertible

Yes- the C50 option. I didn't realize the grate fit that may years, however can't image GM produced that many corvette convertibles with rear defrosters. I was banking that GM took advantage of using that grate on several model cars to save on tooling costs. Thanks for the response.

[Joe L.]

Re: Rear Defroster Vent Grate on 71 Convertible

If I'm not mistaken, the rear grills, plus the front plenum grill and wiper door are all die cast aluminum.

You might want to check out the cost of a used grill before you go ahead. I would expect a used grill to be cheaper than having one machined from aluminum, and it would an authentic replacement.

Chuck------


I think you're thinking of the rear deck "Astro Ventilation" grilles. Those were zinc dicast. I believe the C-50 convertible defroster grille was stamped steel, but I'm not 100% sure.

[Chuck S.]

Re: Rear Defroster Vent Grate on 71 Convertible

Chuck------


I think you're thinking of the rear deck "Astro Ventilation" grilles. Those were zinc dicast. I believe the C-50 convertible defroster grille was stamped steel, but I'm not 100% sure.

Yep, you're right. The C50 option is not that common, and I had never paid close attention to the ones I've seen. Congrats on guessing what the OP was asking from "appears to be a stamped piece".

Was this defroster used on any other GM car? My first guess would be it's Corvette only, but if you thought you needed your rear window defrosted in those days, this would have been the only way to do it on a larger car...it was long before embedded wires in the rear glass.

[Vince L.]

Re: Rear Defroster Vent Grate on 71 Convertible

It's a stamped steel piece. Attached you will see the pictures of the one I got my hands on to have machined. It will be a different process and metal, but my guy believes he can get it to look pretty original. This has been tough to find and for a reasonable price. I called around a bunch of place from Texas east and the best I could do after many no goes was get one attached to the rear deck lid. Too much money and my deck lid is already painted. Corvette Country had one and Paul was willing to work with me to make a duplicate.

[Joe L.]

Re: Rear Defroster Vent Grate on 71 Convertible

Yep, you're right. The C50 option is not that common, and I had never paid close attention to the ones I've seen. Congrats on guessing what the OP was asking from "appears to be a stamped piece".

Was this defroster used on any other GM car? My first guess would be it's Corvette only, but if you thought you needed your rear window defrosted in those days, this would have been the only way to do it on a larger car...it was long before embedded wires in the rear glass.

Chuck------


Rear window defoggers were used on other Chevrolet cars as far back as 1964. I presume these were some sort of "forced air" defogger since, as you say, embedded element defoggers were a long time from being invented. While the basic systems may have been the same between Corvettes and other cars, I don't think that very much, if any, of the Corvette C-50 system components were shared.