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Getting ready to tackle this job on my 70 LT-1. Even though the bar is not badly rusted, I can't stand the "dimples" from the swollen rivets. Body is off the frame and on a jig, so everything is really easy to get to.
Found this thread that spans 11 years!!! https://www.corvetteforum.com/forums...acement-4.html
Lots of good info. One of the last posts by Willcox indicates scribing before removal so that you can line up the new bar. Plan to do that.
Several references to the Willcox instructions. But, the Willcox site is down, so I can't get those. Any chance someone has a copy?
Planning to leave the bonding strip in place and grind out the rivets like this guy did:
On another note, I need a new front cross member. Available from Ecklers for $449.99 and from Corvette Central for $242.75. I could not find where either was made.
Seems like a huge price difference, assuming they are made in the same place. Zip has the same part for $299.99. I don't mind paying a premium for quality parts; just don't want to pay a premium for the same parts that may be available for much cheaper.
Also, Ecklers lists the same part for 68-72. CC and others show 68 as being different, and 69-72 using the same part.
The 70 bar has 3 threaded holes for a plate. This plate has the 2 h/l relays mounted to it. Other bars have 4 threaded holes where the relays mount directly to the bar.
Quoted from post #5, “At the time that I did mine, I went into it thinking that all reproduction Header Bars could potentially be different than the original GM one. So, I marked up my new reproduction Header Bar to the body during mockup, just to make sure that my headlight brackets would all line up. During that process, I noticed that my reproduction Header Bar sat on the old bonding strip tightly between the old adhesive and it lined up perfectly without any play. Just like the original.
The Wilcox “Installing headLamp Header Bar” document (attached) is really good and it is what I followed to replace my rusted out header bar.
I didn’t have to cut the header bar in pieces first or pry it to get it off. I just ground off the rivet tips with a zip cutter and ground deep enough into the old rusted header bar so that there was no rivet metal sticking out grabbing the header bar. The header bar just fell out.
I then used a Dremel and a flat end metal cutting bit to grind out the galvanic corroded rivet remnants from under the bonding strip. In order to get all of the aluminium rivet remnants removed, the holes became the size of a quarter and about a 1/8” to 1/4"deep. DO NOT GO TOO DEEP TO GO THROUGH THE FIBERGLASS PANEL!
I mocked up the new header bar and marked a couple of locations for alignment then used SEM 3974 to adhere it using clamps.
I did not cut mine up either. Cut out all the rivets, and although it did not fall out, it didn't take much persuasion.
My old header bar as no rust through, just some very light surface rust; so I will be reusing it.
I will sandblast, then paint (leaving the mating surface blasted) then adhere. Seems like a lot of guys are really high on the Lord adhesives.
I did a lot of other work today, but did not cut the rivets out of the bonding strip. I wanted to make certain I knew what size there were.
Attached is a pic of a rivet head from elsewhere on the car (#4 body mount reinforcement). I am assuming this head is the same size as the ones in the bonding strip for the headlight reinforcement bar. It is a little smaller than a dime. I have an assortment of small hole saws, and was planning to use that (very judiciously) to remove the rivets from the bonding strip.
Unfortunately my header bar rivets were so swollen and disintegrated, that I personally don't know what the original size was, sorry.
I had to carve out about the size of a quarter to get all the galvanic corroded rivet remnants removed.
I happen to use SEM39747 cuz i have the special application gun and the SEM product has never failed me on other projects. There are a few different similar products out there that fit other folks needs
Cheers,
Richard
Success. Got all 36 cut out without any damage to the fiberglass.
As you described Richard, I had to cut about a nickel to a quarter size hole to get all the old corroded aluminum out.
I found the perfect cutting stone; about 7/8 in diameter with a cupped head. It cut right through the bonding strip. Once it hit the rivet in the middle of the cup many of them just popped out. I had to dig about half out; then scrape all the powdery residue..
The three rivets on both sides at the ends could not be reached with my mini die grinder, and I don't have a 90 degree mini grinder. So, I used a pointed carbide rotary file and cut all the way around rivet, then dug it out.
Ordered some SEM39747.
I am also planning to replace the two shoulder belt reinforcements and the #4 body mount reinforcements. Seeing how they were originally held on with these same rivets, I am thinking I might just use plastic pins for alignment purposes only, and bond with a thin layer of the same panel adhesive. Once the body is mounted, there is not stress on the pins. As this is a different subject, I will start a new thread. I want the car to look good, but don't plan on ever having it judged. Just not my bag.
04-28-2024, 10:31 AM
Headlight reinforcement bar replacement
