AN5 Airframe Bolts, 5/16-24 Thread, 5/16″ Dia, Undrilled Shank, Alloy Steel 125 KSI, Cadmium Plated (Choose Grip Length)

Order AN Bolts by Grip Length, Not Overall Length

This is the single most common ordering mistake with AN hardware. The dash number on an AN5 bolt describes the grip — the smooth, unthreaded portion of the shank — not the total length of the bolt. Measure the combined thickness of everything you are clamping (brackets, washers, spacers, bushings) and buy the bolt whose grip matches that stack. The threads should never sit inside the hole. If your stack falls between two sizes, take the next longer grip and make up the difference with AN960-516 and AN960-516L washers under the nut.

Every AN5 bolt, from the shortest to the longest, has the same 0.531″ of thread. That length is deliberate: it accommodates one full-height nut plus one AN960-516 washer with correct thread engagement. UHL (Under Head Length) is simply grip + 0.531″.

A note if you are cross-shopping AN sizes: the dash number does not mean the same grip in every diameter. A -13 in this series is a 0.938″ grip, because thread length grows with diameter while the overall under head length for a given dash stays fixed. Always read the grip column for the diameter you are actually buying.

What the “A” Means

AN bolts were originally designed around a castellated nut and cotter pin, so the base part number — AN5-13, for example — indicates a drilled shank. Adding an “A” to the end (AN5-13A) means undrilled shank and undrilled head, intended for use with a self-locking nut. Every bolt on this page is the undrilled “A” version. This is by far the most common configuration in modern race car, robotics, and airframe work, where self-locking nuts have largely replaced castle nut and cotter pin joints.

Specifications

Size Chart — AN5 Grip Length, UHL, and Weight

Find the row whose grip matches your clamped stack thickness, then select that dash number from the dropdown above.
A handy one page guide and size chart for all common AN bolts can be found here.

Bulk pricing

Discounts apply automatically in the cart and can be mixed across any combination of grip length in this listing — all count toward the same total.

• 25 – 50 bolts — 5% off
• 51 or more bolts — 10% off

No code needed; the discount is applied at checkout.

Why AN Hardware Instead of Grade 5 or Grade 8?

An AN bolt is not simply a strong bolt. It is a controlled bolt. The shank diameter, head dimensions, grip length, thread length, and material are all held to a published specification, so an AN5-13A from one manufacturer interchanges with an AN5-13A from another. Commercial graded hardware controls only the strength class; the shank length, thread runout, and grip are whatever the manufacturer found convenient.

The behavior under overload matters just as much. At 125 KSI minimum tensile, an AN bolt is not the strongest fastener you can buy — a Grade 8 cap screw is rated higher. But AN bolts are substantially less brittle. Overstressed, an AN bolt tends to yield and bend before it separates, which in a suspension or control linkage is the difference between a car that limps back to the paddock and a component that lets go without warning. That toughness, combined with the guaranteed unthreaded grip that keeps threads out of a shear plane, is why AN hardware remains the default in aircraft and open-wheel chassis construction.

If you need higher strength in the same envelope, look at close tolerance NAS shear bolts at 160 KSI.

Recommended Torque

Standard published values for a 5/16-24 fine thread fastener, clean and dry, torque applied to the nut (per AC 43.13-1B, Table 7-1):

Always defer to the torque specified by your chassis manufacturer, kit designer, or maintenance manual where one exists. Add the nut’s running (prevailing) torque to these figures when using an all-metal locknut. Cadmium plating is a dry film lubricant in its own right — do not add anti-seize or oil and then apply dry torque values, or you will over-tension the bolt.

Need a Drilled Shank or Drilled Head? We Can Get It.

We stock the undrilled AN5-dashA configuration only. The other three drilling configurations are available to us on special order, usually with short lead times.
Call 1-844-F1PARTS (1-844-317-2787) or email sales@formularaceparts.com with the part number and quantity and we will quote it for you.

Note that the letter goes before the dash number in the drilled head configuration: a drilled head AN5-13A is written AN5H-13A. Drilled versions carry their own NSNs and are not interchangeable with the undrilled part for certification purposes.

Applications Beyond the Race Track

AN5 is a workhorse structural fastener anywhere a controlled grip length and a predictable failure mode matter more than raw tensile numbers:

• Road racing and motorsport — rod end and spherical bearing mounting, wishbone and bellcrank pivots, damper and pushrod clevises, steering arms, wing and bodywork mounting, seat and harness anchorages.
• Experimental and homebuilt aviation — the standard 5/16-24 airframe bolt for control system hardware, bracketry, spar and fitting attachment, and engine mount structure on kit-built and amateur-built aircraft.
• Robotics and competition robotics — arm and linkage pivots where the smooth grip acts as a bearing surface and the threads stay clear of the shear plane; drivetrain and gearbox mounting.
• Drones and UAS — airframe joints, gimbal mounts, and payload attachment where an aerospace-traceable fastener is required and weight is critical.
• Aerospace ground support and tooling — jigs, fixtures, and test rigs built to airframe practice.
• Maritime — rigging hardware, control linkages, and deck fittings, though note that cadmium plating is a sacrificial coating, not a stainless finish; ask us about corrosion resistant alternatives for continuous saltwater immersion.
• Light industrial and automation — machine guarding, linkage pivots, sensor and actuator mounting where a defined shoulder is needed.

Matching Nuts and Washers

• MS21042-5 — all-metal self-locking jetnut. The standard partner for an undrilled AN5 bolt and the lightest option.
• AN365-524 — nylon insert self-locking nut.
• AN316-5 — thin jam nut for use as a check nut on rod end adjustment.
• AN960-516 — standard flat washer. AN960-516L is the thin version, useful for fine-tuning grip.

Also Available

We carry the companion diameters in the AN airframe bolt series. Contact us if you need a dash size, a drilled configuration, or a bulk quantity not shown.

• AN3 — 10-32 thread, 3/16″ diameter.
• AN4 — 1/4″-28 thread, 1/4″ diameter.
• AN6 — 3/8″-24 thread, 3/8″ diameter.

Bulk and OEM quantities: we quote volume pricing on AN hardware for teams, manufacturers, and integrators. Call 1-844-317-2787 or email sales@formularaceparts.com.