Racing Fasteners - The Ins & Outs Of Nuts & Bolts

Nuts and bolts are very simple parts when viewed from a philosophical perspective. But in actuality they are quite complex when you consider the metallurgy and the exactness in the manufacturing processes required for the fabrication of these parts.

By and large they are completely ignored components on the racecar until they break or cause an issue of some sort. The majority of racers really do not understand nuts or bolts and their suitability or lack of suitability for specific applications. And, for the most part, they do not need to have that deep of an understanding. But as a racer you need to develop a greater understanding for all the components on your car, and this includes nuts and bolts.

The racer's application of fasteners is not much different from the average person's. In 99 percent of the applications on your racecar you really only have two choices, Grade 5 or Grade 8. These grades of bolt will work for almost every application on a racecar outside of engine and transmission hardware.

The most violent lesson a racer can learn is if a bolt breaks during competition. It does not matter if the bolt is holding a bracket on the car or a suspension component, a break is a break. The impact to the racer and racecar may be varied, but nonetheless a breakage usually means the racer is forced to take notice of the fasteners on the car. Most are overdesigned and have a much higher yield or failure point than we will be placing on a given fastener. Suspension fasteners are a good example.

Breaking bolts is a situation that 99 percent of the time is completely preventable if we learn how to select the right hardware for the given application and we give it reasonable care.

From a racer's perspective, nuts and bolts are the primary methodology for holding the car together. We may start with an OEM frame and weld tubes and sheetmetal together to form a structure, but the other parts that make the car a racecar are held in place primarily with nuts and bolts. The trick is making sure we match the bolt and nut to the job we will be asking it to accomplish.

At this point we need to define what a bolt is and how it works. When you tighten a bolt up or use a nut against a stud, exactly what happens? How is that bolt and nut combination holding anything together? A bolt is really a spring and the tightening of the nut or bolt stretches the bolt, and the action of the bolt trying to return to its original length is what develops the clamping force that holds your car together. Although it is sometimes difficult to visualize that this is what is happening, stretching the bolt is where the majority of the clamping force is being developed.

The amount of force that can be developed with a bolt and a nut or a stud and a nut is incredible. Just think about a connecting rod in a race engine. If the racecar is powered by a V-8 engine and it is making 800 horsepower (not an unreasonable number in today's world) then that is 100 horsepower per cylinder being contained by two bolts and two nuts. And we expect these two bolts to not fail over the course of a season. In fact, we may use the same bolt and nut multiple times over multiple rebuilds. That's not the best option but the reality is that racers will be racers and if the bolt and nut look good it will get reused.

The automotive world is filled with technological wonders that demonstrate how the engineering community has done some wonderful things. Nuts and bolts are no different, as the engineering and metallurgical sciences have really given us products that we take for granted. We have some wonderful racing vendors who build exceptional products that are made to the same or better standards than many aerospace components. The racing community benefits greatly from the aerospace and the automotive industries, insomuch that they have developed specifications and standards that govern the manufacture and material content of nuts and bolts. The racing community has been the benefactor of this standard and specification development. That said, we still expect bargain-basement prices for a set of rod bolts that will survive in a harsh racing environment.