1968 riveted gas lid

[Jeff P.]

[Gary B.]

Re: 1968 riveted gas lid

McMaster Carr sells tubular rivet installation tools. You can form the rivet with the tool and a hammer. Each size rivet takes a different size tool.

https://www.mcmaster.com/tubular-rivet-installation-tools/

I bought one, then used my small South Bend engine lathe to make different sizes. Bought steel rod, different sizes at my local ACE Hardware.
I would paint the door first, set it on a soft piece of felt, then hammer the rivets down. I think that's the process GM used?
GB

[Jeff P.]

Re: 1968 riveted gas lid

Thank you for the advice Gary.

[Joe R.]

Re: 1968 riveted gas lid

Hi Jeff:

I have restored several C2 gas lids. For those rivets, I use a standard rivet-forming tip that I bought several years ago. This tip is designed for use in an air-impact gun, but I use it in a standard drill press without turning the drill press on. The zinc casting material of the gas lid is fairly soft, so just the manual pressure that the drill press allows me to apply is sufficient to form the rivet rim. In effect, I'm using the drill press as an arbor press.

As I understand it, the rivet-forming operation was modified for 1968 to use a spinning ball-shaped tip to form the rim of the rivet. The term applied to this method was "spin rivet." According to John Hinckley, this method did not work well and resulted in a high reject rate in production.

So, I would nor recommend using the spin rivet method for your lid restoration. I think the non-spinning method that I have used for C2 lids is more reliable, and the finished appearance is almost identical to the spin rivet appearance.

When I get home on Sunday, I can try to look up the source I used for the rivet-forming tool that I have. I think it would work very well for the '68 lid.

Note that to fully duplicate the original appearance of the '68 lid, your NOS lid should be painted body color on the underside BEFORE you form the rivets to attach the lid to the chrome hinge.

[Joe R.]

Re: 1968 riveted gas lid

Hi Jeff:

Per my earlier post, below is the rivet-forming tool that I used on midyear lids. I used the tool for 1/8" rivets, #4504:

Solid & Semitubular Rivet Tools | Rivets in Stock

To form the rivet heads on midyear lids, I simply chucked the tool in a drill press and, WITHOUT TURNING THE DRILL PRESS ON, used the drill press as an arbor press to form the rivet heads. I formed each head just a little at a time, inspecting the rim in between iterations to confirm that the tool was well centered and that the rim was forming outward rather than inward.

Comparing samples of midyear lids to '68 lids, I found some slight differences in the rivet stud dimensions:

Midyear stud: .125" diameter stud with a .060" center hole
1968 stud: .112" diameter stud with .070" hole

So, you can see how the '68 stud had much thinner walls, causing the formed rivet head to be weak and prone to breaking off.

The photo below shows an original lid with four surviving factory rivet heads. Next to it is a NOS lid that shows what the studs looked like before they were formed.

When you attach your NOS lid, I have two suggestions:

1) Before forming the rivets, consider putting some JB Weld in the recess that contains the four studs, to physically glue the lid to the hinge. If you clean the areas where the JB Weld adheres to the two surfaces, the glue *might* help to retain the hinge on the lid. This would reduce the stress on the weak rivet heads. Lightly clamp the hinge in place with a small C-clamp, clean off any excess glue, and wait overnight for the JP Weld to set up.

2) Before using the tool to form the rivet heads, "pre-form" them with a conical shape (similar to a counter-sink) to spread the tops slightly and get the rim of the studs headed in the right direction, outward from the center hole. This helps to ensure that when you press the tip with the rivet-forming tool, the rim will spread outward rather than caving in toward the center.

[Jeff P.]

[Joe R.]

Re: 1968 riveted gas lid

Hi Jeff:

Per the information in my post #5, the tool that I used on midyear lids is available from rivetsinstock.com, at the following URL:

Solid & Semitubular Rivet Tools | Rivets in Stock

There is a photo that shows the shape of the tip, which is designed to spread and roll over the rim of a rivet or hollow stud.

I used part number 4504 for 1/8" rivets. Even though the '68 studs are slightly less than 1/8" in diameter, I think the 1/8" tool is the closest match for the job.

I don't recall experimenting with home-made forming tools, but if it was many years ago, perhaps I did that and forgot about it. My sales receipt for the 4504 tool is dated 2006. I have been very happy with the results I get with that tool, so I haven't used anything else since then.

As I'm sure you have figured out, you only get one chance to get the rivets properly formed on your NOS lid, so I encourage you to take your time and form each rivet just a little bit at a time. That gives you a chance to take corrective action if the rim is not forming properly. In my experience, the most common problem is that the tool is not perfectly centered on the post, so the rim starts getting squashed to one side. If you see this starting happen, you can usually take corrective steps to move the tool back to center. I do this by tilting the lid a little bit.

The other common problem I have had is that part of the rim starts folding toward the center, rather than toward the outside. That's why I recommend pre-forming the rim with a conical shape to get the rim spreading out slightly at the top before using the rivet-forming tool. For the pre-forming operation, I press on the hollow stud with the tip of a counter-sink tool (tool NOT spinning!).

If you want to practice before doing the studs in your NOS lid, consider purchasing some 1/8" hollow rivets to practice with. You can drill some 1/8" holes in a steel plate and practice your technique on the aluminum rivets. Just make sure that the aluminum rivets are protruding through the steel plate by approximately the same amount as the gas lid studs will be protruding through the hinge.

Please post the results of your project when it's done. I've long had an interest in attempting to make a 100% original looking '68 lid. One problem that has held me back is that for 100% original appearance, the back side of the NOS lid has to be painted body color BEFORE it is attached to the hinge. Since your car is apparently out for paint, you can have the painter take care of that part for you.

[Jeff P.]