ARP 3/8-24 Hex Nut Kit (10 pack)

Precision-Ground Chrome Moly Hardware That Refuses to Back Down

The ARP 200-8634 is a 3/8-24 fine thread hex nut kit built from premium Chrome Moly Steel with a durable black oxide finish. Each kit includes 10 nuts rated to 180,000 PSI tensile strength, giving you the clamping force required for high-stress engine, drivetrain, and suspension applications. ARP 200-8634 uses a 9/16-inch socket size for fast, clean installation across a wide range of bolt patterns. Whether you are building a race motor, replacing worn factory hardware, or assembling a high-performance street build, these hex nuts deliver the reliability ARP is known for worldwide.

Key Features

• Chrome Moly Steel construction for exceptional strength and fatigue resistance
• Black oxide finish provides corrosion protection and a clean appearance
• 3/8-24 fine thread pitch for precise torque control and secure fastening
• 9/16-inch socket size for compatibility with standard tool sets
• 180,000 PSI tensile strength rating for demanding high-load applications
• 10-piece kit provides enough hardware for a full job or restocking your supply
• Universal fit for use in engine, drivetrain, suspension, and custom fabrication applications
• Manufactured to ARP's stringent quality standards with consistent dimensional accuracy

Specifications

What's Included

• 10x ARP 200-8634 3/8-24 Chrome Moly Hex Nuts, Black Oxide

Frequently Asked Questions

The ARP 200-8634 uses a 3/8-24 fine thread pitch. Fine thread provides greater clamping force per torque increment compared to coarse thread and is the standard choice for high-performance fastener applications where precise torque control is critical.

You need a 9/16-inch socket to install the ARP 200-8634 hex nuts. This is a standard size compatible with most 3/8-inch and 1/2-inch drive socket sets commonly found in automotive tool kits.

The ARP 200-8634 is rated to 180,000 PSI tensile strength. This rating exceeds the requirements of most performance engine, suspension, and drivetrain applications and is far superior to standard OEM or grade 5 hardware.

These nuts are manufactured from Chrome Moly Steel, which offers an excellent balance of high tensile strength, fatigue resistance, and machinability. Chrome Moly is widely used in motorsports and high-performance builds where standard carbon steel fasteners are insufficient.

Black oxide provides a mild corrosion-resistant coating that reduces oxidation in low-moisture environments and gives the hardware a clean, uniform appearance. For environments with heavy exposure to moisture, additional lubrication or anti-seize is recommended.

Yes. The ARP 200-8634 is a universal hex nut kit intended for use anywhere a 3/8-24 fine thread nut is required. Common applications include rocker arm studs, cylinder head accessories, suspension linkages, custom bracket fabrication, and general high-performance assembly work.

Each ARP 200-8634 kit includes 10 hex nuts. This is typically sufficient for one rocker arm set on a V8 engine or a variety of other single-application jobs, with extras remaining for future use.

Yes. ARP nuts are dimensionally matched to work with ARP studs and bolts using the same thread specification. Using matched ARP hardware ensures consistent thread engagement, torque accuracy, and maximum clamping load without galling or cross-threading.

ARP recommends using ARP Ultra-Torque fastener assembly lubricant during installation to achieve accurate torque-to-clamp-load results. Using the correct lubricant is essential for reaching and maintaining the rated clamping force specified in your application's torque specs.

Installation Instructions

1. Verify the mating stud or bolt is the correct 3/8-24 fine thread specification before installation.
2. Clean all mating threads thoroughly with a thread chaser or wire brush to remove debris, corrosion, or old thread locker.
3. Apply a small amount of ARP Ultra-Torque lubricant to the threads and the underside of the nut bearing surface.
4. Thread each ARP 200-8634 nut on by hand until finger tight to confirm there is no cross-threading.
5. Torque each nut to the specification required by your application using a calibrated torque wrench and a 9/16-inch socket.
6. Follow the correct torque sequence for your application (e.g. center-out for cylinder head work) to ensure even clamping load distribution.
7. Re-torque after initial heat cycling if the application involves thermal expansion, such as engine or exhaust components.

WARNING: This product can expose you to chemicals including lead and phthalates, which are known to the State of California to cause cancer and reproductive harm. For more information go to www.P65Warnings.ca.gov.