RADIUS ROD PIN

Description

A radius rod pin—sometimes called a torque rod pin—is a critical suspension component used to secure the radius rod (also known as a torque arm or radius arm) to the axle or chassis. Here’s a focused breakdown of its purpose, design, and practical considerations:

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🎯 What Is a Radius Rod Pin?

• Function: Secures the radius rod’s forked or clevis end to the axle or frame, allowing the rod to pivot and control fore-and-aft wheel movement—particularly under braking or acceleration

• Typical Design: A hardened steel or alloy pin, often inserted through aligned holes in the rod and mounting bracket or fork.

• Retention: Usually held in place with a cotter pin or snap ring inserted through a cross-drilled hole in the pin .

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🔧 Common Specifications

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🚜 Applications & Usage

• Suspension Applications: Found on older tractors (e.g. Ford 9N/2N/8N), trailers, and aftermarket radius rod linkages—especially in drag‑race or vintage vehicle setups using hairpin or four-bar suspension designs

• Installation & Fit: Press-fit or free-sliding, pin should not rotate unintentionally; lubrication helps ease removal. If corroded or worn, reuse can cause sloppy steering behavior.

• DIY Replacement: Some owners create replacement pins by modifying a grade‑8 bolt — cutting length, removing excess thread, drilling a cotter hole, and applying anti‑seize—though original hardened steel is preferable for load-bearing tension/torsion

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🧠 Why It Matters

• Control & Safety: The radius rod restrains longitudinal wheel movement; without a firm pin connection, braking or acceleration forces can lead to axle shift, wheel-hop, or misalignment.

• Wear Management: Over time the mounting holes (yoke or clevis) can wear or elongate. If tolerances grow, you may need to replace bushings, the pin, or even the rod itself

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✅ Quick Summary

• The radius rod pin is a hardened fastener providing a pivot point between a radius rod and axle or frame.

• It is typically retained via cotter pin through a cross‑drilled hole.

• Sizes and exact specs depend on vehicle model—e.g. classic Ford tractor versions use ~5/8″ × 4.68″ pins.

• Always use high‑strength material and correct tolerance; DIY bolt substitutions are workable but not ideal under load.