Question on applying body assembly rivets

[67HEAVEN]

I've seen a discussion on this a couple of years ago, but for the life of me I can't remember the answer.

The C2 body is full of aluminum rivets to secure various metal brackets and braces to the fiberglass. EXAMPLE.........the seatbelt "underbody" reinforcement brackets; the seat track "underbody" reinforcement metal brackets; etc.

What tools and procedure are used to achieve a nice flat, round result.

We drilled a couple of holes in a piece of scrap metal and applied a straight-on hit with both a ballpeen and a bodywork hammer with the following messy results.

The flat-head aluminum rivets just collapsed sideways instead of mashing cleanly.

What am I missing?

 

[Dave65]

I also restore aircraft. The "correct" way is with a rivet gun on the head of the rivet and a bucking bar (hunk of steel) on the end that is being compressed. The following link will show you what they look like.

http://www.aircraftspruce.com/catalog/topages/menus/to20.php


These are aircraft tools and are fairly expensive (even more than Corvette stuff). If you do not have one, a $9.99 air hammer from Harbor Freight would probably work for the gun. You still need a flat faced tool to put in the gun. A 16 oz ball peen hammer can be used for a bucking bar.

The mistake most people make at the beginning is to use too much air pressure on gun. It takes very little force to compress the rivet - it should feel more like vibration than hammering. Three or four - two second bursts should do it. Keep the bucking bar (or hammer) centered on the rivet and perpendicular or the head will bend over.

It is actually very easy.

Dave

 

[PTighe]

'67, I use a 40 lb piece of a steel trailer hitch as a buck and a 5 pound hammer with a 6" handle. It gets tough in the tight spots though, and it takes practice. The key to getting the rivet "mushroomed" properly is to hit the tip exactly perpendicular to the head of the rivet. PT

 

[Islander]

Ooooooo, I'm going to need pictures for this one 'cause I have no idea what the process would look like.....

 

[67HEAVEN]

I have an air hammer, and I suppose I could find a flat-faced tool to put in it.

I'm puzzled by how I'm going to get to some of these areas.

The example I gave above concerning the seatbelt reinforcement brackets (below the floor) is relevant. Each of them requires six rivets to hold them in place and the location will make access very difficult.

Thinking back to the mid-60's when they built these cars......I'm trying to imagine how the boys in the St. Louis factory did this. I assume that the body panel (or section) in question was held in a jig and various locations on the jig acted as bucking bars. The worker simply inserted the rivets in the holes, loaded the panel (or section) into the jig and then smacked each of the rivets home with a gun. Sound feasible?

If that is how it was done, and I'm assuming it was done prior to the panels or sections became one big car, it must have been much easier than doing the same thing now to a complete body.

I guess it's a two-man job for many of these locations as there is no practical way for one person to be able to reach both ends of the job -- example, inboard seatbelt reinforcement brackets, etc.

Also, due to obstructions incumbent in an assembled body, it may be nigh on impossible to get a bucking bar and/or the impact-applying tool to-the-point-of-action.

I would appreciate hearing more comments.....and thanks for all the info so far.

Has anyone out there actually done this to the following items?
- seatbelt reinforcement brackets (both inboard and outboard)
- clips that hold the wiring harness channel along driver's sill

 

[JohnZ]

Here's what you need to set aluminum body rivets - an air gun, a regulator, and a rivet-set tool. Insert the rivet first through the parts (head on the fiberglass side), snip off the end of the rivet so you have about 3/8" of shank exposed, back up the head with a solid object ("bucking bar"), and shoot it with a burst from the air gun (about 20 psi works well). See the next post for a close-up of the setting tool.

 

[JohnZ]

Here's a close-up of the rivet-setting tool for the air gun - it's concave so it mushrooms the end of the rivet evenly into a round head. I get mine (for 3/16" rivets) from Aircraft Tool Supply, www.aircraft-tool.com . Works like a champ; practice for ten minutes to experiment with the air pressure that works best for you, and have at it!

 

[67HEAVEN]

It's all becoming clearer now, John.

The info about snipping off the excess shank and using a concave tool are real helpers.

As always........thanks. :BOW

 

[Dave65]

A couple of comments from the aircraft repair world.

The length of the rivet showing before it is bucked should be 1 1/2 times the diameter of the rivet. The surface of the bucking tool should be flat and corvette factory rivets were done with a flat bucking bar.

The weight of the bucking bar for the size of dead soft aluminum used in the Corvette is about 1 pound which is why I suggested a 16oz ball peen hammer as a good substitute. Too much will flatten it too quickly and the rivet will not properly fill the hole, too little will not flatten it enough before the aluminum work hardens and begins to “resist” flattening anymore.

May be more than you want to know.

Dave

 

[Doc Rebuild]

Corvette Aluminum assembly rivets

Those Corvette Aluminum assembly rivets are such a noble and maligned object. I too though force (hammering) was applied to the shaft. But my Boeing Corvette owners explained otherwise as did Dave. I think only us amateurs do it backwards.

Because of the various thickness’ of materials to be assembled, each different rivet length has a specific GM part number as seen in the AIM. There are about 6 main ones of this particular style in a 1963-1982 Corvette AIM. Note that most rivets use a formula of a head OD 2 times the shaft OD. However, these Corvette rivets are specials in that the head OD is 4 times the shaft OD and very thin to boot. But they serve admirably on a soft fiberglass substrate.

Correlate the AIM GM part number and you can determine the length required for your project. If you have the blueprints, you can determine the exact length required for each various rivet. If you don’t have the blueprints you can look them up in the following chart which summarizes that information.

http://www.docrebuild.com/dr-r-web/9024025.html

Those particular parts that appear to be difficult to rivet upon the car are most definitely, so difficult to do. However, after the separate pieces of fiberglass were actually manufactured, often they already had those steel pieces riveted on before the individual pieces of fiberglass were assembled into the finished product. In tours of the assembly plant, C3 era, I remember seeing the workers mounting steel brackets to fiberglass pieces that were not yet in the cars. Another time I watched one worker staple rubber pieces to an inner fender skirt that was not yet mounted in the nose. He had a specifically contoured form that allowed the fiberglass skirt to sit perfectly flush and supported upon this form - but rotated 90 degrees. And he placed the rubber seal in place ands went bang, bang, bang, bang, bang with the staple gun. Fairly quickly. Took it of the form and placed it on another stack of finished skirts and grabbed skirt another to start all over again. Later they were glued into the nose. The same was true of many steel brackets used throughout all base models.

In 1981 when the new plant opened, my buddy and I were asked to not take as “many” tours. For a few days, we repeatedly toured the plant and there were many visitors and the tours were busy. They bribed us with some commemorative stuff. They, the GM plant personnel were really nice every time I have been a visitor.

Geoffrey Coenen
Wanted 69 L-89 convertible. No project

 

[JohnZ]

As Doc indicated, all of the riveting of metal parts to fiberglass was done in off-line subassembly tooling in the Body Shop, before the individual panels were bonded to the body on the main line (which is why access to replace them is so limited on a finished body shell). Access was wide open for riveting in the subassembly fixtures.

 

[John Mcgraw]

Also, smaller sub-assemblies are usually riveted together with a rivet squeezer. The alligator or "C" squeeze can produce the exact same product every time. At Boeing, all rivets that could be installed with such equipment, usually was. The driving and bucking of rivets was usually reserved for those areas like skins where the rivet was more than a couple of inches from an open edge.
Regards, John McGraw

 

[StingRay6T3]

67 Heaven, Where did you purchase the aluminum rivets from?

Damian

 

[69MyWay]

I ran into this as well.

I worked with the folks at Paragon Reproductions to make sure I got the exact correct length rivet for each part.

I was not after an exact factory duplicate smash.

However, I too learned that you must have the correct length rivet for the hole. When I tried to put ones in with the shank too long, they just bent over and looked like crud.

I used a combo of hammers and flat steel plates from my hydraulic press. My wife Nikki was a real trooper, because she would get on one side of the body, and me on the other and we pounded away. As soon as I got the correct length for the job, it went very easy.

I also used the old trailer hitch ball in one spot under the rocker.

 

[67HEAVEN]

67 Heaven, Where did you purchase the aluminum rivets from?

Damian

www.zip-corvette.com

 

[JohnZ]

Doc Rebuild and Paragon are great sources - they have the correct "soft" rivets with the plain exposed heads.

 

[67HEAVEN]

This company makes a "Corvette" rivet tool.

http://www.micro-controls.com/cartools-brivet.html

Opinions?

 

[Dave65]

It is a Bubba tool. It will likely work but is not the correct way to set the rivet. Aircraft Tool Supply, as suggested by JohnZ, has a $229.95 rivet gun set that will do everything you need to do.

http://www.aircraft-tool.com/shop/detail.asp?PRODUCT_ID=2602KT&ReturnPage=search_result.asp?PageNo=1

The ATS tool set will set the rivet properly, it will not damage the fiberglass, and the assembly will have its full strength. With the other tool you are beating on fiberglass with a hammer - if you are very good it will work - if not you will crack the fiberglass and have a weak rivet.

I buy a lot of tools because in my opinion 80% of doing a professional job is having the right tools.

My 2 cents.

Dave

 

[69MyWay]

Dave,

The problem is some of these rivets are deep in the interior of the body...meaning that you more or less need two people. One on top of the rivet to hold it in place, and the other on the other side of the car with the punch and hammer.

It is a very crude way of doing things. You are correct, if you miss there will be damage to the fiberglass.

The good part is you don't have to hit these soft rivets all that hard to get them to pound down, and little to none of it is on an exterior area, so it can't be seen when the carpet and trim is back on/in the car.

 

[67HEAVEN]

It is a Bubba tool. It will likely work but is not the correct way to set the rivet. Aircraft Tool Supply, as suggested by JohnZ, has a $229.95 rivet gun set that will do everything you need to do.

http://www.aircraft-tool.com/shop/detail.asp?PRODUCT_ID=2602KT&ReturnPage=search_result.asp?PageNo=1

The ATS tool set will set the rivet properly, it will not damage the fiberglass, and the assembly will have its full strength. With the other tool you are beating on fiberglass with a hammer - if you are very good it will work - if not you will crack the fiberglass and have a weak rivet.

I buy a lot of tools because in my opinion 80% of doing a professional job is having the right tools.

My 2 cents.

Dave

Is the rivet gun simply an air hammer by another name? If so, all I need is the rivet set and bucking bar.

If the rivet gun is different from an air hammer.......what's different?