Wheels and tires on a race car are, literally, “where the rubber meets the road.” Racers spend hours and hours debating the perfect tire for the perfect lap. But, commonly ignored is how those wheels and tires are affixed to the car. Wheels are attached by lug nuts on wheel studs, and the reason people often ignore these items is that they rarely fail on a street car and thus don’t require much attention. However, on race cars, this is a very different story.
With sticky race tires, big horsepower, big brakes, and aggressive driving, the stress applied to studs and lug nuts will often destroy stock factory components. When these parts fail, goodbye wheel, and hello car accident. It is hard to win a race when you are upside down and on fire. For a couple of Benjamins and a few hours in the garage, you can install stronger, lighter parts to ensure your wheels stay where they should be — on your car.
We decided to upgrade the wheel studs and lug nuts on our Double Nickel Nine Motorsports 1990 Acura Integra RS NASA Honda Challenge car. From years of racing, we learned the hard way that stock factory wheel studs are designed for passenger car trips to the store to pick up toilet paper, not to handle heavy curb strikes and wheel-to-wheel racing.
We trust ARP bolts for all of our necessary fasteners, and they have a set of strong chromoly wheel studs for Honda/Acuras. With a simple click of the mouse, all we had to do was wait for the UPS man to show up and we could get to work.
Once we ordered the wheel studs, it was time to source a set of lightweight and sturdy lug nuts for holding the wheels on the studs. For this, we entrusted the folks over at Skunk2 Racing who have tons of racing wins under their belt and have been leaders in the import racing scene for years. There are plenty of lightweight aluminum lug nuts on the market (you want hot pink ones?). However, only Skunk2 Racing makes a set made with forged aluminum which makes them stronger (precisely what we are looking for in racing).
Once our parts arrived, we took the time to compare the stock components with our new aftermarket racing components. At first glance, it is obvious the ARP wheel studs are longer, which is an advantage for using different wheels and wheel spacers on race cars. The ARP wheel studs are manufactured from premium-grade, heat-treated 8740 chromoly steel, nominally rated at 190,000 psi tensile strength, and cadmium plated for extra durability.
According to the folks at ARP, “Our studs can easily handle the tremendous acceleration shock loads and lateral forces found in racing applications. Our ARP wheel studs are must-have replacements for competition vehicles.” The ARP wheel studs have a bullnose end which makes it easy to thread on lug nuts during fast pit stops. This design feature assists in not cross-threading a lug nut with an impact gun.
With the longer wheel stud comes added weight, and racers hate adding weight, especially when it comes to rotational mass. But, we were able to counteract this with the lighter Skunk2 Racing forged aluminum lug nuts. Jeff Giovino at Skunk2 Racing detailed some of the design advantages of its lug nut, “Our Skunk2 forged lug nuts are hard-anodized for superior corrosion resistance and are extremely lightweight.”
“With an industry-leading weight of 23.5 grams, each Skunk2 lug nut helps reduce unsprung weight without compromising strength. Each lug nut also features a perfectly tapered end for maximum wheel-to-lug contact, as well as durable threads for added longevity.” To see if Jeff’s claims on weight were legit, we put their lugs on our scale to compare. He was right on the money; they were super light, which made us very happy at the race shop.
Once we were convinced the parts we chose were the correct ones, it was time to install them on our race car. In most cases, you will not be able to replace wheel studs without taking the hubs off, so the first step is to remove the hubs. Using our handy, inexpensive Harbor Freight press, we pressed out the stock wheel studs.
With the right tools (a press instead of a hammer) this is a straightforward and quick process. The key to using a press is to ensure your parts are in-line as you press the components out. To find the perfect setup for this takes some ingenuity and creativity. We use equal length sockets to hold things in just the right place to make pressing studs out super easy.
Assembly is the opposite of disassembly when it comes to pressing-in wheel studs. An important thing to remember here is which direction to press the studs in. Once a hub has no studs in it, it isn’t always obvious which way the studs go (until you do it wrong and try to re-attach the hub to the car). Our recommendation is to mark the hub “outside” with a magic marker before you start pressing-out studs. The ARP studs, which are manufactured with extremely accurate tolerances, pressed into our Acura hub perfectly.
With our studs pressed-in and the hubs re-attached to the car, we took the time to inspect the match between our wheels and our new Skunk2 Racing lug nuts. We use lightweight Enkei RPF1 wheels and wanted to ensure the tapered edge of the lug nut mates correctly with the wheels. The match was right on.
What we liked about the Skunk2 Racing lug nut was the amount of surface area at the tapered edge that contacts the wheel once the lug nut is torqued down. We also liked the large number of threads mating to the stud. Both of these features will provide more strength in the wheel attachment.
The ARP studs and Skunk2 Racing forged-aluminum lug nuts allow our team to use a higher torque value for attaching the wheels to the race car. If we tried to torque our wheels at 100 foot-pounds with a stock stud, there is a good chance we would strip the threads or break the stud.
With the 8740 chromoly ARP stud mated with the 7075 forged-aluminum Skunk2 Racing lug nut, we can have confidence the hardware can handle the torque specs needed for racing. As a standard practice, we torque our lug nuts after every session on track to ensure we don’t lose a wheel. We also keep a box filled with spare lug nuts and tools to clean the threads inside of a lug nut or the threads on a wheel stud for emergencies.
We bolted our wheels onto our Honda Challenge car and torqued them down to our specifications. We drove the car around and then re-torqued again to ensure our wheel studs were pulled-in all the way. Once we knew everything was set, we headed to the track and put some hard miles on the new studs and lug nuts. Good news! A wheel didn’t fall off!
The forged lug nuts and chromoly wheel studs give me a lot of confidence when I am running the car at the limit. There are plenty of things to worry about when racing, losing a wheel should not be one of them. Ensuring you have the correct hardware in place means you can drive hard and not worry about this sort of thing. Metallurgy is everything. If you want to nerd out on metallurgy and learn all kinds of things about metal brittleness, check out the technical information from ARP here.
Swapping out wheel studs and changing lug nuts is an easy project and one I recommend to anyone taking their car to the track. Regardless if you are a wheel-to-wheel road racer, an autocrosser, or an HPDE/track day fan, adding performance tires and running around a racetrack will put stress on your car beyond that of the manufacturer’s design. Be smart and upgrade. In my opinion, this modification is a no-brainer.