Choosing the right 3/8 nylon lock nut depends on strength needs, environment, and how often you expect to reuse fasteners. This guide highlights five solid picks suited for common automotive, machinery, and DIY projects. Each product is evaluated for best use cases, potential limitations, and what makes it stand out. Use the buyer tips below to compare locknuts by material, corrosion resistance, and installation torque.
Summary at a glance: the top five picks cover Grade 8 high-strength options for demanding tasks, corrosion-resistant stainless steel variants for outdoor or humid settings, and economical Grade 2 options for general purpose projects. The table helps you quickly assess suitability for vibration-heavy assemblies, rust-prone environments, and storage-friendly kits.
| Product | Material / Grade | Count | Best For | |
|---|---|---|---|---|
| 3/8-16 Grade 8 Nylon Insert Locknuts (100 Pack) – Makers Bolt | Grade 8 high-strength steel, nylon insert | 100 | Heavy-duty mechanical assemblies, high vibration | Higher torque may be needed; check compatibility with bolt grade |
| Vifmy 35 Pack 3/8″-16 Nylon Lock Nuts – 304 Stainless | 304 stainless steel, nylon insert | 35 | Outdoor, moisture-prone or corrosion-prone settings | Smaller count per pack; stainless steel price premium |
| Vmuter 45 Pack 304 A2-70 Nylon Lock Nuts – 3/8″-16 | 304 stainless steel, nylon insert | 45 | Vibration resistance in automotive and machinery | Weighty stainless option; store away from humidity |
| BNUOK 20Pcs 3/8-16 Nylon Lock Nuts – 304 Stainless | 304 stainless steel, nylon insert | 20 | Spare fasteners for varied projects | Lower quantity; may require reordering for bulk tasks |
| 3/8″-16 Nylock Hex Nuts (100 Pack) – Makers Bolt | Grade 2 steel, nylon insert | 100 | General-purpose fastening and light-duty projects | Grade 2 is lower strength than Grade 8 |
Note: The selections emphasize a mix of strength, corrosion resistance, and value. When selecting, consider whether the part will face vibration, moisture, or outdoor exposure, and match the nut material accordingly. Each product listing includes a clear thumbnail image and direct link for quick comparison.
3/8-16 Grade 8 Nylon Insert Locknuts by Makers Bolt (100 Pack)
Best for high-load, high-vibration applications. The 100-pack includes 3/8″ nuts with a 9/16″ wrench size, 0.453″ nut height, and coarse 16 threads. Grade 8 heat-treated carbon steel ensures high strength. Choose this if you need a bulk, heavy-duty Nylock option for machinery or automotive assemblies. Limitation: higher-strength steel can be stiffer to install in tight tolerances.
Vifmy 35 Pack 3/8″-16 Nylon Lock Nuts (304 Stainless)
Best for environments prone to rust or moisture. These 3/8″-16 Nylock nuts are made from 304 stainless steel with a nylon insert for anti-loosening performance. The set includes 35 pieces and is ideal for outdoor or humid settings where corrosion resistance is important. Limitation: higher price per piece compared with carbon steel options.
Vmuter 45 Pack 304 A2-70 Nylon Lock Nuts
Best for vibration-prone automotive and machinery work. The 304 stainless construction resists rust while the nylon insert prevents loosening under motion. The 45-pack value set includes an organized storage case for portability. Limitation: stainless steel can be heavier than carbon steel alternatives.
BNUOK 20Pcs 3/8-16 Nylon Lock Nuts
Best for spares for diverse projects. These 20 pieces are 3/8″-16 nylon insert locknuts made from 304 stainless steel with a standard inch thread. Their nylon insert helps resist loosening due to vibration. Limitation: moderate count may require restocking sooner for frequent use.
Makers Bolt 3/8″-16 Nylon Lock Nuts (25 Pack) Grade 8
Best for mid-bulk jobs needing Grade 8 strength without the full 100-count. This 25-pack includes 3/8″ nuts with a 9/16″ wrench, 0.453″ height, and coarse 16 threads. They are hardened, medium carbon alloy steel for strong fastenings. Limitation: not ideal where corrosion resistance is critical unless used with protective coatings.
Hard-to-Find Fastener Coarse Nylon Insert Lock Nuts – 3/8-16 (100)
Best for robust locking in heavy-duty joints. The set features a built-in nylon collar to prevent loosening in vibration-heavy settings and uses a coarse 3/8″-16 thread. Stainless or hardened steel variants are adaptable for various torque needs. Limitation: weight and bulk may be excessive for tiny assemblies.
Buying Guide
What material should you choose?
Carbon steel with nylon insert offers strong performance at a lower cost. Stainless steel (304/18-8) provides excellent corrosion resistance for outdoor or humid environments. Grade 8 nuts deliver higher shear strength for heavy-duty use, while Grade 2 is suitable for light- to medium-duty tasks.
How important is corrosion resistance?
For outdoor equipment or marine environments, stainless steel Nylock nuts are typically preferred. For indoor or dry settings, carbon steel options with nylon inserts can be more economical.
When is more pack-count better?
High-count packs are beneficial for workshops, repair shops, or ongoing projects. If you only need a few replacements, smaller packs or singles reduce upfront investment.
What about installation and torque?
Nylock nuts rely on a nylon insert to resist loosening. Ensure proper torque as over-tightening can degrade the nylon insert over time. Choose a nut with a height and thread length that matches your bolt for reliable performance.
Quick comparison tips
- Best for vibration-heavy tasks: Grade 8 Nylock with nylon insert.
- Best for moisture-prone environments: 304 stainless Nylock nuts.
- Best for bulk, general-purpose use: Grade 2 Nylock nuts in larger packs.
FAQ
- What does Nylock mean? It refers to nylon insert lock nuts that resist loosening from vibration or torque.
- Can I reuse nylon lock nuts? Reuse is possible but performance may decline after multiple cycles; inspect for cracks or wear.
- Are stainless Nylock nuts stronger than carbon steel? Stainless resists corrosion; strength depends on material grade and design.
- What wrench size fits 3/8″ Nylock nuts? Most 3/8″ Nylock nuts use a 9/16″ wrench or hex driver, depending on the exact nut height and design.
- Which pack size should I buy for workshops? For ongoing projects, 35–100 piece packs provide a balance of cost and replacement availability.
- Do nylon locks degrade in high heat? Elevated temperatures can reduce nylon’s locking efficiency over time; consider material and operating range for high-heat applications.