PARTS IS PARTS

NUTS AND BOLTS

ARP AND THE ART OF THE FASTENER

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o say that hot rodders are detail oriented would be an understatement. We fabricate custom brackets, balance assemblies, machine tolerances, and gap sheet metal in an effort to build the best performing and best looking hot rods we can. But when’s the last time you considered the fasteners that hold it all together? They’re literally the foundation of

our cars, maintaining the structural and mechanical integrity of everything we build. And they play a significant role in a car’s aesthetic as well.

Recently we had the opportunity to learn more about a company who’s been considering fasteners—and perfecting them—for decades. Automotive Racing Products, or ARP, is probably more familiar to those who follow motorsports. From drag racing and NASCAR to Formula 1, tractor pullers, and hydroplanes, you’ll find their fasteners wherever reliability is not only a factor in performance, but in safety as well. But their use isn’t limited to mammoth horsepower, high stress applications. ARP offers beautiful polished stainless steel and chrome moly fasteners and kits for a wide variety of hot rod, vintage muscle car, and modern performance applications. They’re significantly stronger than OEM, or even the best hardware you’ll find at parts houses and hardware stores, and for external applications they’re the nicest looking fasteners going.

Although we have used ARP fasteners for decades, we’ve only used them on engines. Our friends at Johnson’s Hot Rod Shop introduced us to the idea of using them for our chassis and the rest of our cars as well. After seeing ARP fasteners used throughout the chassis and driveline of Jon Wright’s Deuce coupe (TRJ #64) and the land speed racing “Stupidbaker” (TRJ #65), our interest was piqued. We visited their expansive Southern California facility last summer. It’s an impressive operation that handles every step of the manufacturing process, turning raw stock into the finished product you’ve likely seen in ARPs trademark blue and yellow packaging.

The more we learned, the more it became apparent that there were many ways to improve the quality and looks of our hot rods by paying a little more attention to the nuts and bolts we use. After all, if you’re upgrading your current car, and especially if you’re starting a new project, you’ll need fasteners. It seems wise to invest in hardware that lives up to the level of quality, performance, and aesthetics embodied in the rest of the car.

FASTENERS FIT FOR THE SNAKEWe’ve all heard the adage that a chain is only as strong as its weakest link. For hot rodders, all too often that weak link is a fastener. Choosing the properly sized and spec’d hardware and installing it correctly is up to us—the hands-on hobbyist or professional builder. But designing and making that hardware to standards that will live up to the rigors we’ll expose them to is the manufacturer’s responsibility. And ARP has intimate knowledge of exactly the kind of rigors we’re referring to.

Gary Holzapfel started the company in 1968. After years as a machinist in the aerospace industry, he first opened his doors as a grinding and thread rolling shop for other hardware manufacturers. Thread rolling is just one of several operations involved in making hardware, and typically manufacturers rely on a network of subcontractors to perform those various tasks. As Gary’s company grew, so did their capabilities. Mike Holzapfel, Gary’s son, came on board, and they began adding equipment to perform more of the tasks involved with manufacturing. At first much of their clientele was concentrated in the aerospace industry, but a friendship with a well known racer changed that.

“As the company grew, one of the shops they moved into was near Don Prudhomme’s shop in the San Fernando Valley,” explains Chris Raschke, ARP’s Director of Sales and New Products, and an employee of nearly 20 years. “Mike Holzapfel was into hot rods, and they all began hanging out.” Hearing about the fastener failures Prudhomme and other drivers and engine builders were experiencing, Gary began refocusing his efforts. By 1975 the company was re-named Automotive Racing Products, and they were manufacturing almost exclusively for the automotive and performance aftermarket.

Along with making fasteners and kits for racing teams like Prudhomme’s, Dick Moroso’s, Wood Brothers’ NASCAR operation, and others, ARP began developing products like head stud, rod bolt, and main stud kits for street applications. The first kits were for the smallblock Chevy, but today they offer over 2,700 kits for 567 engines, from flathead Fords and early Hemis to the most modern performance power plants.

The key benefit of all of their fasteners lies in their strength, and to understand the difference between ARP and standard Grade 8 or commercial stainless hardware it will help to explain their approach to manufacturing. The Holzapfel’s recognized early on that in order to maintain complete control over the quality of their hardware, two things were necessary: they had to start with the very best materials available, and they needed to bring every step of the manufacturing process in house.

“We had to keep bringing equipment in,” says Chris Raschke. “Not only was it inconvenient to outsource various operations, but there was no way to control the quality.”

PUNCHING YOUR WEIGHTRegarding materials, ARP uses more than 10 different alloys—some of which are proprietary. For our purposes, we’re mostly concerned with high strength stainless steel and chrome moly. With the exception of 8740 chrome moly, all of the raw

By Curt Iseli | Photography by Geoff Miles

ARP (Automotive Racing Products) makes high strength fasteners for a wide range of applications, from hot rod and muscle car drivelines and chassis to high performance racing engines. They handle all manufacturing in house in their Southern California facilities. Fasteners are made from a variety of materials (some of which are proprietary to ARP), from stainless steel and chrome moly to titanium. The visual impact these nuts and bolts have on hot rods is impressive.

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materials come from a Pennsylvania-based mill known for producing a premium product (their 8740 is sourced offshore because they can no longer source a strong enough premium material domestically). “To give you an idea of the strength, Grade 8 hardware has a minimum tensile strength of 150,000 psi, and commercial stainless is about 90,000 or less” Chris says. “Our entry level stainless has a minimum tensile strength of 170,000 to 190,000 psi. We get that strength from the quality of the materials, and the patented technology we use in manufacturing.”

That technology begins with forging what are known as blanks from raw stock (coil for nuts and bolts, bar stock for studs). A blank is a bare fastener, cut to length and formed with the specified head through either hot or cold forging. Most manufacturers rely on “hot heading,” which involves heating the metal and forming the head under pressure. The problem is that the heat reduces the hardness of the metal, particularly at the head and just below it, which is the most critical part of the fastener. The majority of ARP’s hardware is formed using a multi-die cold forging process. The metal is work hardened while it’s being formed, helping to make the fastener’s hardness consistent from end to end.

Heat treating and threading come next, and these are two more processes that contribute significantly to the strength of ARP’s hardware. But to better understand why, there are a couple of terms that should be explained. Fasteners undergo a great deal of testing to determine hardness, tensile strength, and fatigue strength. Tensile strength refers to the amount of stress that can be applied while stretching a fastener before it fails. Fatigue strength has to do with the number of times the

material can be stressed prior to failure. “I like to think of it in terms of boxing,” Chris says. “Tensile will tell you how hard a hit you can take. Fatigue will tell you how many rounds you can go.”

Many manufacturers roll or cut the threads into the blanks prior to heat treating them in large heating bins. At ARP, the blanks are heat treated first. Using special racks, each piece is separated and hung vertically, insuring full penetration and increasing tensile strength in the process. Shot peening, straightening, and grinding for concentricity and to achieve the desired diameter follows. The threads are then rolled (not cut) after heat treating, which increases fatigue strength 20 times over hardware that’s threaded prior to heat treating.

During production, the thread machines are stopped shortly after each run is started so that samples can be inspected. Thread quality and dimensional accuracy is checked before the parts go through tensile and fatigue testing. And even these tests are performed differently at ARP. In aerospace, fatigue testing is based on components going through a maximum of 130,000 test cycles. If each piece lasts 85,000 cycles, the batch passes. ARP realized that in racing engines operating at 18,000 rpm, it takes just over five and a half minutes to go through 100,000 cycles. With that in mind, ARP’s test samples are run through

ARP’s polished stainless steel fasteners, like the studs and the hex head and 12-point nuts and bolts shown here, are beautiful. But more importantly, they’re manufactured from premium materials via labor-intensive processes that make them significantly stronger than commercial stainless steel and even Grade 8 hardware. Material hardness is consistent throughout the entire bolt, and threads are machined to a .001” tolerance–five times greater than aerospace standards.

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one million cycles, and they only pass if all samples survive a minimum of 350,000 cycles. Once the process is complete, the production run can continue (though additional samples are still checked randomly).

Finally, the fasteners are tumbled and polished or black oxide-coated prior to packaging for distribution. The entire manufacturing process takes place in ARP’s complex in Santa Paula, California. The fasteners are then transported 14 miles southwest to their packaging and warehouse facility in Ventura.

KIT OR CUSTOM, THEY’VE GOT WHAT YOU NEEDWe mentioned the staggering number of bolt and stud kits ARP has developed, and there are plenty more in the works. Their R&D department, which is also located in the Ventura facility, is constantly evaluating new products to serve hot rodders, racers, and other automotive enthusiasts.

“Whenever we design a kit, we find an engine, dismantle and clean it, and get new factory fasteners to torque-tension test and figure out factory clamp loads,” says Chris. “Then we measure and figure out if we can put more thread into the block, figure how much clearance we have in various areas, and determine what material and design will increase the fastener performance. We usually start with heads, mains, rods, balancer, and flywheel, then pick and choose what else we want to do outside of those.”

They’re currently working with Johnson’s Hot Rod Shop and others, including Detroit Speed, on some chassis kits to complement their extensive driveline kits. But ARP is a company that was built on custom applications, and if you’re looking for fasteners unique to your project, they’re happy to help figure out what you need and create a custom package for you. For example, we’ve got plenty of hardware throughout the engine in the TRJ Deuce roadster, from the heads to the headers, but after seeing other uses for their fasteners we’ve ordered up a custom stud kit for the quickchange cover.

With over 150,000 square feet of facility floor space, ARP has clearly grown leaps and bounds from the one-man operation Gary Holzapfel started in 1968. But through it all, they’ve maintained their grassroots feel. A third generation now works for the company (Mike’s son Ryan works in nut forming—one of the more complex operations), and they still operate under the singular mission of providing hot rodders and racers with the finest fasteners possible.

Incidentally, ARP regularly host tours and rod runs at their Santa Paula facility, and even operate a full-service restaurant, Hozy’s Grill, on the premises. Gary’s father, “Hozy,” was a great cook, and apparently passed his skills down to his son and grandson, so they named their restaurant in his honor. If you’re ever near Santa Paula, we recommend you to stop by and check out their impressive facility.

ARP’s Ultra-Torque fastener lubricant is resistant to wear and has a 360-degree melting point, both of which help prevent galling of stainless steel. But it’s recommended for use with all fasteners because it allows you to get within five percent of a target preload on the first, and each subsequent, torque cycle. Other common lubricants can take as many as eight cycles to achieve the same result. Fasteners are available individually or in kits for everything from head studs and exhaust collector fasteners to intake bolts. The smallblock Chevy intake bolts shown in the bottom photo provide a six point OE-style look in a high strength polished stainless finish.

PARTS IS PARTS

ARP

1863 Eastman Avenue, Ventura, California 93003

(800) 826-3045 | www.arp-bolts.com

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