Stemco 449-4973 Pro-Torq Axle Spindle Nut – For Trailer Axles

The Stemco 449‑4973 Pro‑Torq® spindle nut is engineered for heavy-duty trailer and drive axle applications, delivering precise bearing adjustment, robust locking, and reliable durability. Ideal for fleets, OEMs, and repair shops looking to enhance wheel-end performance.

🌟 Key Features

• Thread Size: 3 1/4″‑12 (3.25″ diameter with 12 threads per inch)

• Across‑Flats (Nut Width): 4 3/8″ (8‑point socket)

• Nut Thickness: 1.000″

• Outer Bearing Cup/Cone: 580/572 series

• Keeper Part Number: 450‑4973

🔩 Why It Matters

• High-precision adjustment: Bearings can be set in 0.001″ increments for optimal end play and longevity

• Single-nut design: Eliminates overtightening complications associated with jam nuts, helping avoid bearing thrust issues

• Durable locking: Spring-steel keeper locks into nut at multiple positions, securing bearing preload reliably.

• Maintenance-friendly: Works seamlessly with Stemco’s Pro‑Torq keeper system and supports consistent servicing protocols.

🛠️ Application Specs

• Compatible Axles: Dana EST‑230‑P (post‑2006), Meritor, Eaton, Mack, Ford, Freightliner, IHC, Kenworth, Peterbilt, Volvo, Western Star, and other commercial tandem axles rated 30,000–50,000 lb

• Common Use Cases: Drive axle wheel ends on semi-trailers, tractor-trailers, tankers, and vocational vehicles.

🔗 Cross-Reference & Interchange

Equivalents and compatible part numbers include:

• Stemco: 449‑4973

• Keeper: 450‑4973

• Volvo OEM: 21052655, 8084235, 94404‑0001/0002, 3099532

• Alternative aftermarket: BWP M‑5221, NSI M‑522

✅ Benefits at a Glance

1. Precision-fit bearing adjustment in 0.001″ increments.

2. Reduced wheel seal wear and extended tire life.

3. One-step installation — no jam nuts required.

4. Positive locking system ensures stable, safe axles.

5. OEM-grade quality backed by Stemco’s reliability.