'73 Lower Rubber Air Dam w/Rivets

[John M.]

Re: '73 Lower Rubber Air Dam w/Rivets

Peter- The rivets I was telling you about may not work after all. I think the ones I have are too small. Let me know how your search for the rubber is working out. John

[William M.]

Re: '73 Lower Rubber Air Dam w/Rivets

The air dam itself is not reproduced, so you need to find an NOS one (good luck) or make it yourself. Doctor Rebuild has the metal retaining strips.

[Rich C.]

Re: '73 Lower Rubber Air Dam w/Rivets

Those wide head rivets are the same ones that were used to attach urethane bumper to 'lower bumper reinforcement'. I spent a LOT of time looking for a source with no luck. The '73 AIM shows the part #'s for these rivets are the same, for '73 anyhow. My Oct. '72 built C-60 454 didn't have this lower extension.

'73 LS-4 454

[Terry M.]

Re: '73 Lower Rubber Air Dam w/Rivets

Those wide head rivets are the same ones that were used to attach urethane bumper to 'lower bumper reinforcement'. I spent a LOT of time looking for a source with no luck. The '73 AIM shows the part #'s for these rivets are the same, for '73 anyhow. My Oct. '72 built C-60 454 didn't have this lower extension.

'73 LS-4 454

Like I said way up higher in this thread -- I think there was a TSB to add this thing. If I get a chance I will look, but I won't be able to scan it until I go back to work on Tuesday. Besides that we have 1968-69 manual to work on this weekend so you guys will take a back seat.

[Ken K.]

Re: '73 Lower Rubber Air Dam w/Rivets

My 73 LS4 with C60 Was made 3-1-72. I can measure all of the parts if you want. I have had problems with uploading pictures on Threads. If you give me your email address I will send photos. The height is .920 for the backing strip, and the thickness of the rubber airdam is .200. Here is a link to two pictures. You can call me if you want 352-243-4863
http://kkosanda.shutterfly.com/112

[Ken K.]

Re: '73 Lower Rubber Air Dam w/Rivets

The height is .920 and the thickness of the backing strap, the rubber airdam is .200 thick. Here is a link to two pictures. You can call me if you want 352-243-4863

[Ken K.]

Re: '73 Lower Rubber Air Dam w/Rivets

Here is a photo of the backing bracket;

[Terry M.]

Re: '73 Lower Rubber Air Dam w/Rivets

There is some data in TSB (Technical Service Bulletin) 73-T-28. I will put up a scan tomorrow -- if my day job permits.
For the moment: "To improve low speed cooling, an additional grille extension was installed in 1973 Corvettes produced after Vehicle Identification Number 1Z37Z3S410722."

Rivets are 3/16" diameter Aluminum Pop Rivet, 3/8" Length, 5/8" Head Diameter.

The TSB applies to 1970-1973 454 with C60 and adds a flex fan for any 1970-1973 454 with C60 that encounters overheating. This may explain where all the "shark's tooth" fans went.

You can get the part numbers, not that it will do anyone any good from the scan tomorrow.

[Terry M.]

Re: '73 Lower Rubber Air Dam w/Rivets

Here you are. Oops I have to make them smaller. I just hate that.

Your file of 596.2 KB bytes exceeds the forum's limit of 293.0 KB for this filetype.

So we will be without the PDF image because this board will not support this file size.

If anyone knows how to change the size (bytes) of a PDF I have two of them I can email to you. Aparently because the TSBs are printed on yellow paper, and the scanner picks up the background color as "noise" the file size becomes too large to post here. I don't have anything at work or home (that I know of) to change the file size of PDFs. I reduced the resolution of the images, but that didn't change the file size.

Here you go -- thanks to Vinnie Peters.

https://www.ncrs.org/restorer/TSB%2073-T-28%20Page%201.pdf

https://www.ncrs.org/restorer/TSB%2073-T-28%20Page%202.pdf

[Peter G.]

Re: '73 Lower Rubber Air Dam w/Rivets

Thanks Terry and all! This should be enough information to make this item. Just have to find the rubber piece.

[Peter G.]

Re: '73 Lower Rubber Air Dam w/Rivets

We'll I have collected all the materials to fabricate this rubber air dam extension. Rubber, metal strips, metal primer paint, semi gloss black paint and rivets.

The only thing that was NOT mentioned here was how much rubber in width that I will need to cut a V-Shape just under 4" rubber flap? I got a 1/8 thickness 12" wide by 51" long.

I think that will work. I just soaked my plastic air dam bolts with lubricate to help the bolts come out easier.

I intend to place the plastic air dam on the rubber or template (in the middle) and go both sides from the center line just under 2"?

Does this sound right? Mathematics and Alegbra was never my strong point in school! Maybe I should have studied harder?

Thanks everyone.

If and when this part is finished..maybe I could start another patent and sell to Doc Rebuild. I am sure that I am not the only one with RPO's LS4 and C60 that would like to have this piece.

[Ken K.]

Re: '73 Lower Rubber Air Dam w/Rivets

My rubber air dam is .200 thick, 3 5/8 tall. If you put it down flat, it is about 10 1/2 inchs from the bottom of the V to the top of the ends. Hope that helps.

[Peter G.]

Re: '73 Lower Rubber Air Dam w/Rivets

Ken..thanks...I believe 1/8 inch is the same as .200? The 10 1/2" from the bottom of the V to the top of the sides should work. I guessamate with 12" so I should have approx. 1 1/2 inch left.

[Kenn S.]

Re: '73 Lower Rubber Air Dam w/Rivets

1/8" would be .125. .200 is closer to 1/4" (which would be exactly .250). Unless I'm jumping into a discussion without understanding.

[Peter G.]

Re: '73 Lower Rubber Air Dam w/Rivets

Ok everyone I am done with this. It is complete thanks to my co-fabricator John Marisco of the NCRS Rocky Mountain Chapter and ALL the researchers that posted here to help us get this done. A big THANK YOU!

It took most of the day on Thursday and sometimes you can over calculate the numbers so at the end I just made a drawing on a template and then we measured it to make sure it was what it was supposed to be.

It took almost two hours to get the air dam back on as some of the flat washers were hitting the metal braces (and my shoulder and back) didn't speed things up when getting up and down.

Here is a pic of the completed rubber air dam with rivets.