If you’ve been around any kind of high-performance engine, you know the name ARP. Short for Automotive Racing Products, the company was started by (and is still owned by) Gary Holzapfel back in the late ‘60s when he realized there were no commercially available studs and bolts up to the unique challenge of racing. He had a history in making aerospace-level fasteners and started a racing-specific bolt making shop in his Southern California garage to address that concern. The company now has several buildings in Santa Paula and Ventura, California, with more than 115,000 total square feet where raw steel goes in one end and fully finished fasteners come out the other.
Point at any high-end race car (and most entry level home builds as well) and you’ll be able to find ARP fasteners on it. ARP makes a fastener for virtually any part on a car, and supplies specialty hardware to top Formula 1, IndyCar, NASCAR, and NHRA teams. Even John Force is one of their endorsers.
ARP’s director of sales and marketing and general “Jack of all trades” Chris Raschke gave us a tour recently and explained all the complicated steps a fastener goes through from raw bar stock to a finished piece of jewelry that gets the ARP stamp.
There are other bolt companies out there. When asked why ARP was better, Raschke said, “Everything ARP makes is to a recipe, and you have to follow that recipe. If somebody says, ‘I can make an 8740 rod bolt just as good as ARP’…if you look at it like a chocolate chip cookie, you can go out and buy a premix and get poor quality chocolate chips, and follow the recipe, and you’ll get a cookie in the end, maybe. But the ARP way is to purchase the finest ingredients, follow the recipe very carefully, and you’ll come out with a better chocolate chip cookie.”
Good analogy there, and something to remember when choosing any high-end part of any kind over cheaper versions of the same. Now, here’s how ARP makes its fasteners.
The Raw Material
In order to ensure optimum quality control, ARP controls all aspects of the manufacturing process, from start to finish, in-house. If something is wrong with a fastener, ARP is quickly able to figure out why and fix it, instead of being at the mercy of an outside contractor. The process begins right at the foundry, where ARP orders only premium grade materials, including several proprietary alloys. The ever-popular 8740 chromoly steel, for example, comes from the mill in four distinct grades. The lowest is “commercial,” which is followed by “aircraft quality.” ARP uses only the top two grades (SDF and CHQ), which cost twice as much but provide for defect-free fasteners. These materials come in bar stock (for studs) and huge coils (for bolts).
Hot and Cold Heading
Transforming raw material into a fastener begins with “hot” and “cold” heading processes, where the head of the bolt is formed to the shank, which supports the threads will eventually go. The coiled raw material is fed into big, insanely powerful machines, straightened and cold forged or induction-heated and formed under tons of pressure.
Following the basic shaping process, the material is heat-treated to desired levels. A gang of bolts, studs, nuts, or whatever is loaded into a rack and put into an internal quench furnace (IQF) where they are heated to a specific temperature for a specific time, then they go into what Raschke calls “the Maytag”, where they are washed off, then moved to a draw oven to bring the Rockwell hardness within spec. Different hardness levels are required for different strength levels depending on the part.
Big round vibrators loaded with various types of material are used to debur the un-machined fastener and polish the stainless steel ones.
The Grinding Department is where all studs are centerless ground to ensure that they are perfectly concentric. As many as ten machining steps are required to achieve this level of accuracy, and there are many machines in this area that are set up differently for whatever part is being machined at the time.
The thread-rolling operation (to MIL-S-8879A specs) is done after heat treat, which accounts for a fatigue strength up to 10 times higher than fasteners that are threaded prior to heat-treat. There are several different types of machines that roll threads, depending on the fastener.
Nut Forging and Tapping
ARP manufactures nuts in a multi-step process that begins with raw material being fed into a giant forming device that “blanks” the hex and 12-point nuts and continues with highly sophisticated automated threading equipment that taps each nut with an accuracy of .001˝ (which is five times higher than the aerospace standard). This ensures an exceptionally close-tolerance fit between the bolt/stud and nut. A series of CNC-threading machines are used to accurately tap the threads in nuts. Tolerances held are five times better than aerospace standards.
Nuts then go to metal finish, including a black-oxide coating of chromoly or polishing stainless steel to a brilliant luster. Raschke told us making a nut is far more difficult than making a stud or bolt.
Steel rusts. That’s a fact of life, so any fastener exposed to air must have some type of coating, which ARP gives its bolts and nuts. Of course, stainless steel does not rust or overly corrode, but a stainless fastener looks better if it’s polished or coated in some way. ARP offers most fasteners either polished or coated with a black oxide that looks almost like anodizing, but is really nothing more than an appearance item. Raschke calls it “accelerated rust.” But they look good when you use them.
R&D And Quality Control
A series of special checking devices are employed to monitor the quality of threads. For every thread size, there is a checking device, and several steps to quality inspection.
When you manufacture a product, you must have a shipping department to send it out to buyers. Once an ARP fastener is finished going through the many steps of manufacturing, it gets stored in a warehouse in buckets with all the other ARP fasteners in a warehouse next to the shipping department. When you (or your local speed shop or engine builder) order a set of bolts, they’re boxed, weighed, and shipped right from ARP’s Santa Paula facility.
And that’s how ARP makes its fasteners. More complicated than you thought, huh? ARP stuff is often more expensive than the competitors and that cheap Chinese garbage, and you may be asking yourself, ‘Why should I pay extra for a bolt?’ Remember Raschke’s chocolate chip cookie analogy. Why would you eat at the French Laundry (Google it) when you could just have McDonalds? Think about it. ARP also makes more than fasteners for race and performance cars. While we were there, we saw some super-secret bolts, made for a local aerospace company, about which Raschke said, ‘You didn’t see this.’ They offer serialized fasteners for the top Formula 1 and IndyCar teams, and who knows what other applications we don’t know about. We wouldn’t be surprised if there were ARP bolts in the CIA’s spy planes that are watching you right now.