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Most racers are focused on generating maximum horsepower and getting it to the ground. Often overlooked are wheel bolts that can withstand shear loads of up to 30,000 psi in a 11,000 horsepower nitro car and more than 15,000 psi in a door knocker.

To apply their expertise to this topic, we contacted two companies with more than 100 years of wheel stud experience: ARP and Mark Williams Enterprises.

As early as 1974, Williams developed the basic setup for professional cars, and has been successfully used since: a sturdy 5/8-inch screw-in stud, fixed to the back by a lock nut, and has a larger 11/ 16-inch shoulders to accommodate aluminum drive wheels. This places the wheel in the center of the stud instead of relying on the taper of the lug nut. However, in view of the wide variety of rim thicknesses on the market and the desire to minimize the rotating weight, many variables need to be considered. But first, let's check the shoulderless studs.

This diagram shows the various parameters involved in selecting the best shouldered wheel stud length.

The strength of ARP is the manufacture of special press-fit wheel bolts with pitches of 7/16-20, ½-20, M12 x 1.50 and M14 x 1.50. There are more than three dozen dedicated stud part numbers in the latest ARP catalog. ARP also offers screw-in studs (1/2-20) of various lengths for aftermarket axles, and M12 x 1.50 studs with a total length of 2.955 inches.

In order to achieve the best weight reduction, MW's top-of-the-line kit includes titanium drive studs and aluminum nuts.

Far superior to OEM products, ARP's studs are made of 8740 chromium-molybdenum steel alloy and heat treated to reach 190,000 psi tensile strength. They are cadmium plated to improve durability.

The installation of press-in studs is quite simple, however, ARP studs have a knurled interference fit. If the hole is too large, the studs will rotate. This is why almost all aftermarket car axles and hubs use screw-in bolts.

(Left) ARP's press-in studs are usually application-specific, but for other vehicles, they can be determined by the total length (1), knurled length (2), nose length (3), and knurled diameter (4) Make sure they have multiple thread sizes. (Right) The key dimensions required to determine the correct screwing of the stud include the under-head length (1), thread length (2) and nose length (3). ARP provides six configurations.

For anyone considering modifying OEM shafts to accommodate different studs or drill hubs, detailed instructions can be found in the ARP catalog (free printed copies are available upon request).

MW's shoulder drive studs are available in steel and titanium. A typical installation includes a 5/8-18 stud and a lock nut to fix it. The wheel is fixed in place with split flange nuts and aluminum washers to prevent damage to the wheel.

Screw-in studs are available in a variety of configurations, including hexagonal wrench, 12-point wrench, and allen wrench types. ARP is usually 12 o'clock.

Titanium studs are available and are about 45% lighter than steel studs of the same size. This is an important consideration for racers who strive to minimize the mass of rotation. However, improving performance comes at a price, because the cost of titanium studs is about three times that of steel studs.

MW manufactures its basic nuts from steel and adds a protective galvanized layer.

It is obviously important to choose the right length of the drive stud; the drive shoulder of the bolt should fully engage the wheel. MW recommends that the unthreaded shank of the stud is slightly larger than the total thickness of the brake cap or brake drum and wheel. The washer should be thicker than the part of the shoulder that extends beyond the surface of the wheel.

The base nut can be matched with four different washers with thickness ranging from 3/16 inch to 3/4 inch.

In order to simplify the installation of any type of stud (wheel or other) and reduce the chance of damaging the thread or stud shoulder, MW provides a special stud installation tool that can accept from 5/16-24 to 5/8 -18.

You would not think that low lug nuts will be the focus of a lot of attention, but Williams has developed an efficient setting with encapsulated aluminum washers of various thicknesses from 3/16 to 3/4 inches to compensate for the different The wheel and brake cap are combined and prevent damage to the wheel. The steel Snap-Lock base nut is used instead of the standard flange nut, and there are four washer options.

ARP manufactures a wide variety of press-in wheel bolts, from the sturdy "Speed ​​Studs" (left) used by the NASCAR Cup team to smaller application-specific bolts suitable for more than three dozen vehicles.

For those who want to reduce weight absolutely, MW offers one-piece aluminum nuts made of 7075-T6 aluminum and hard anodized. The one-piece aluminum washer snaps onto the nut and rotates freely. Although they are part of the MW titanium stud package, they can also be used with steel studs.

So you have it...information that you can use to help your car’s transmission system "bulletproof". More importantly, both ARP and MW have experienced technical teams that can provide free and convenient personalized help.

The standard MW stud kit has shouldered studs, steel lock nuts and lug nuts, and 10 pieces of aluminum each.

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