As racers and home garage engine builders, we have long understood the role of quality nuts and bolts as important components of our race cars. All the way back to 2012, we researched the topic with ARP Bolts, coming up with a great article on the hows and whys of fasteners. The full content of this article can be found at The Role Of Engine Fasteners In Critical Engine Measurements.

To help us get a handle on the subject, we enlisted the help of Chris Raschke at ARP. Raschke explains how intricate and precise race car fasteners actually are, “Most commercial and aerospace houses don’t hold the tolerances that we need to hold here for race car parts,” says Raschke.

Most commercial and aerospace houses don’t hold the tolerances that we need to hold here for race car parts. – Chris Raschke

Threaded fasteners allow for the removal and reassembly of parts where other types of solid fasteners are a single-use item. With the wide range of applications where threaded fasteners can be used, there are basically two categories that fasteners are divided into, critical and non-critical.

Raschke was quick to point out there are different categories of fasteners, “We’ve always been known for our connecting rod bolts and our head and main studs, but we make quality fasteners in a variety of different shapes and forms. From bumper to bumper.”

The critical category of fasteners includes the high stress and high load areas like connecting rods, main bearings, and head bolts or studs. These critical fasteners generally have exact tightening specifications and procedures whereas the non-critical fasteners have relaxed tightening specifications.

Examples of non-critical fasteners are pan bolts, timing cover bolts, and valve cover bolts. Because non-critical fasteners do not require a detailed tightening procedure, we limited our focus to critical fasteners in this particular article.

The full article included a section on how ARP bolts are manufactured, from the initial cutting of the wire, through heading, heat-treatment, machining, shot-peening, and finally the finishing process, and packaging.

ARP continues this time-proven process in fastener manufacturing today. With a few slight tweaks, the process is the same as we first saw it in 2012.