All too often, fasteners are overlooked. They are not covered in the media the way that engine or suspension components are, and they rarely receive as much attention as your common rubber or cork gasket. According to Carroll Smith, Team Manager of Carroll Shelby’s Ford GT40 Le Mans project, “There are only two basic structural groups: threaded fasteners and rivets.” Smith understood the value of good fasteners in building winning race cars. In addition to his very popular books Tune to Win, Drive to Win, Prepare to Win and Engineer to Win, he authored what is perhaps the greatest book ever written on race car fasteners, Carroll Smith’s Nuts, Bolts, Fasteners and Plumbing Handbook. Rivets played an enormous role in the success that Carroll Smith had on the track, and he devoted chapters to the selection and use of rivets.
Blind rivets were introduced into the marketplace in the mid-1930’s and over time they have become the unsung heroes of fasteners. Different metals have been used in their construction, but the design has stayed remarkably the same for almost 70 years. We have become so accustomed to seeing the same thing done the same way for so long, that when something new comes along it is often slow to gain widespread acceptance. We’re going to take a good hard look at blind rivets and examine how one company has used modern engineering to advance their technology.
aDP Rivet is changing the way race car builders choose rivets when constructing their race cars.
How Much Value does a Rivet Really Have?
Winning races and Championships does not happen by accident. If you value winning, and winning a lot, then rivets become quite important. “The season’s race championship can rely on just one fastener doing its job,” wrote Smith. “If that fastener shears or loosens, the whole race can be lost – not to mention valuable machinery and perhaps even lives.”
If you think that it’s a stretch to say that rivets can cost a life, let’s consider where rivets are used. With racing’s emphasis on safety, manufacturers of safety devices have been working steadily to improve the quality of their products and the components used in the assembly of these devices.
HANS and Hutchens Devices use helmet hooks anchored to the helmets by rivets, enabling the devices to work properly. Randy LaJoie’s company, The Joie of Seating, has been very selective in choosing the materials used in manufacturing their high-end racing seats. As a testament to the high quality products that aDP manufactures, they have been selected as the official rivet supplier for The Joie of Seating. Discussing the choice, LaJoie explained that aDP manufactures, “a safer rivet, that works better than the rest.”
So, to answer the question of how much value a rivet really has, we can say this: If you like winning races and Championships and if you want to live to be an old racer, rivets are extremely valuable.
Anatomy of a Rivet
An open end blind rivet consists of two basic parts: the rivet body and the setting mandrel (often called “the nail”). The rivet body is essentially a hollow tube shank with a head on the top, providing the seat or seal to the material being joined. The shape of the mandrel directly affects the way the rivet is pulled, as well as its gripping power.
We’ve all seen what happens when a fabricator chooses a rivet that is way too long for the application. This results in the tail of the rivet looking like a poorly stuffed sausage – and that just covers the aesthetics. Needless to say, the gripping strength around the fastener is not evenly distributed when the rivet is too long, resulting in poorly joined metal.
Types of Rivets
The blind rivets most commonly used in race car fabrication can be separated into two categories: open end and closed end rivets. The primary difference between the two is that the closed end blind rivet is closed on the tail end of the rivet and has a larger expansion area to prevent leakage of liquids or vapors. Otherwise, both types of rivets have the same advantages.
Open End Rivets
Strong, low cost
Variety of metals and sizes
Ideal for most applications
Several options in head styles (Domed, Large, Flanged, Countersunk)
Closed End Rivets
Full Mandrel retention
Prevents leaks of liquid and vapors
Expansive capability for strong joints
Open End Rivets and Specialty Rivets
Open end blind rivets are the type most commonly used in race car fabrication, but they are not all the same. Our favorite rivet from aDP incorporates a couple of features that are “extras” in other brands, but are standard in aDP’s Ultimate Rivet line. When you look at the working end of the aDP Ultimate Rivet, you can see that the nail is shaped like a diamond. There are product lines in other rivet brands that feature this engineering (commonly referred to as “Easy-Entry” rivets), and feature all of the same characteristics as open end rivets, but they incorporate a cone shape on the nail for faster installation. aDP has incorporated this as a routine feature in their Ultimate Rivet line. aDP’s rivets also include a broad shoulder on the other side of the cone that helps the rivet “set” into the holes of the material. This expansion ensures that the rivet will have a stronger grip, thereby making a stronger joint between the two pieces being riveted together.
Another element that comes standard on all aDP Ultimate Rivets is the “Multi-Grip” feature. The grooves in the tubular body of the rivet serve to optimize the clamp-up force of the rivet as it is being pulled by the rivet gun. The expansive properties of the Ultimate Rivet accommodate oversized or irregular holes in the metal. The Ultimate Rivet’s ability to easily fill oversized or elongated holes with more strength than regular rivets makes it a one-man show. The aDP Ultimate Rivet literally does the job of three other specialty rivets, and does it better in each specific area than specialty rivets that have been designed for a certain singular task. A race car builder can reduce his rivet inventory by 75% simply by using aDP’s Ultimate Rivets for every rivet application.
Comparing Specialty Rivets to aDP’s Ultimate Rivet
We wanted to test the ability of aDP’s Ultimate Rivets against rivets that were “purpose-built,” so we collected some of the most popular brands of specialty rivets as well as a couple of regular blind rivets, for our somewhat less-than-scientific testing. There are set ISO standards in testing blind rivets, however access to that equipment is limited and very expensive. So, we chose to put the rivets through a more real-world testing procedure. We intended to use them as we would in normal situations and evaluate them based on their own merit.
Test #1: Oversized Holes
The true test of a rivet lies in its ability to work in the most problematic conditions possible. Oversized holes tend to cause the most problems in joining metal with rivets, so this is where we wanted to begin our test.
We drilled two holes in a piece of flat aluminum. Using two rivets, one aDP Ultimate Rivet and a rivet from a popular manufacturer, we drilled two 0.250″ holes in the flat plate. The tube body of the rivets both measured 0.188 on our digital caliper, so we were measuring apples to apples. Using a battery-operated rivet tool, we installed the popular brand rivet into the oversized hole first. After the mandrel snapped, the rivet fell out of the oversized hole (as expected). Honestly, we had expected both rivets to fail this test. A realistic oversized hole would have been 3/8 of an inch, not 1/4 of an inch. To our amazement, the aDP Ultimate Rivet expanded and gripped the aluminum plate. We attempted to check the gripping power by grabbing the tail of the rivet with channel locks and turning the rivet radially in the hole. No dice. The rivet did what it was supposed to do in a significantly oversized hole.
Test #2: Measuring the aDP Ultimate Rivet against the Tri-fold Rivet
We left the aDP Ultimate Rivet in the oversized hole and installed a Tri-fold Rivet into the other oversized hole. The Tri-Fold rivet works like a drywall anchor screw – the body of the rivet compresses and forces three legs out, providing the gripping area on the tail-end side of the rivet. This seemed to work, as the other manufacturer’s rivet stayed in place, but it was evident that the rivet body did not expand to fill the hole. There was noticeable space around the body of the rivet and the edge of the hole. It was also clearly visible that the only gripping power from this rivet consisted of the three areas where the “legs” of the rivet splayed out enough to contact the sheet of aluminum. Once again we used a pair of channel locks to check the clamping power of the rivet in the oversized hole. The Tri-Fold rivet did not meet our expectations for what a good, tight joint should be.
We did a little research into the Tri-Fold or “Exploding” type of rivets and found that they can be useful in the applications that they were originally designed for. Tri-Fold rivets were designed to be used in softer materials because they will not crack the piece that you are working on. That’s perfect for plastics or carbon fiber but in our opinion, it doesn’t work well for structural body panels. It should come as no surprise that a rivet designed for use in softer materials would not have as much expansive properties as a rivet designed for gripping metal.
Test #3: General Appearance
With sponsorship money for racing getting tighter, racers have become even more conscientious about making their cars look as good as they possibly can. Even dirt track racers at the grassroots level have taken the appearance of their cars to the next level. Because rivets are such a noticeable part of a race car’s body, selecting the proper rivet is crucial – not only for function, but also for appearance. In researching rivets for this article, we called National Dirt Late Model Hall of Fame member Barry Wright of Barry Wright Race Cars and asked him which rivets he uses. Wright told us that he uses aDP Ultimate Rivets because, “they clamp hard and the paint stays on the painted rivets. They are priced right, and they look better on the back side. To me, they just have a neater, cleaner look on the back side.”
We checked out what Wright told us, and took a closer look at the tail of the installed rivets. The conventional blind rivets had tails that looked uneven and curved in all different directions. The Tri-Fold rivets had three legs that stuck out, exposing sharp edges that looked like they would do some damage to bare skin if you were trying to remove panels quickly or even clean them. aDP’s Ultimate Rivets were pulled into a compact tail, almost resembling a ball. Wright was correct – aDP rivets have a neat, clean appearance, even on the back side of the joint.
Test #4: Cost
Performance is a great thing, but most of us can’t afford to pay Ferrari prices for Ferrari performance. We’re looking for the best value we can get. The absolute last thing that anyone wants to do is pay for a name brand product when it isn’t the best product on the market. We did some checking around, and our unofficial price comparison showed that aDP’s rivets cost less than the Tri-Fold rivets, and cost slightly more than conventional rivets that are manufactured overseas. aDP’s products are manufactured entirely in the USA, so you can also rest assured when you buy their products that you are putting money directly into the pockets of American workers.
Economically, aDP’s rivets make more sense. Cost vs. performance is a no brainer. aDP’s Ultimate Rivet offers the best buy for race car fabrication.
Our unscientific research was telling in its own right, but we wanted to back it up with some real measurable data. Using our own measuring technique, we compared a top selling brand’s Tri-Fold (exploding) rivet against the Long Ultimate Rivet, Extra Long Ultimate Rivet and the Extra, Extra Long Ultimate Rivets from aDP. Here are the results:
Tri-Fold Rivet: Sheared at an average 421 lbs of pressure.
aDP Long Ultimate Rivet: Sheared at an average 948 lbs of pressure.
aDP Extra Long Ultimate Rivet: Sheared at an average 948 lbs of pressure.
aDP Extra, Extra Long Ultimate Rivet: Sheared at an average 1322 lbs of pressure.
Testing indicated that aDP’s Ultimate Rivets provided more than double the clamping power of the popular Tri-Fold rivet and cost less. Based on testing and professional evaluation from Hall of Fame chassis builder Barry Wright and Craftsman Gold Wrench Award Winner Gary Oliver, as well as professional endorsement from Randy LaJoie, we have to give two thumb’s up to aDP Rivet for changing the way that rivets are made. Armed with the knowledge of what rivets can do, we expect nothing less than aDP Ultimate rivet quality now.
For more information about blind rivet comparisons, click here.
For more information about other products offered by aDP, click here.