Connecting Rods & Related Components for Caterpillar 3406 Engines

The connecting rod is one of the most critical components inside any Caterpillar 3406 engine. It acts as the link between the piston and the crankshaft, converting the piston’s linear motion into the rotating force that powers the engine. A properly fitted connecting rod, along with its bushings, bearings, bolts, and nuts, ensures smooth engine operation, balanced power delivery, and long-term reliability.

Diesel Pro Power supplies OEM-quality and aftermarket connecting rod components for the Caterpillar 3406, as well as compatible options for related models such as the 3408 and 3412. Below you’ll find a detailed catalog of replacement rods, bushings, bolts, and bearings—all designed for different styles of the 3400 series engines, including both old pre-combustion chamber designs and direct injection models.

Complete Connecting Rod Assemblies for Caterpillar 3406

Straight Rod – Old Pre-Combustion Style

Designed for earlier 3406 engines, the straight rod style is robust and simple in design. It is compatible with 3406, 3408, and 3412 pre-combustion chamber engines. These rods are often installed during major overhauls of legacy 3400 series units and remain an excellent choice for operators maintaining older fleets.

Narrow Taper Rod – 6 Degrees (Old Pre-Combustion Style)

This rod variation includes a narrow taper angle of 6 degrees. It allows for slightly different stress distribution on the crankshaft journal and bearing surface, improving performance in certain load conditions. These rods are also found in pre-combustion 3406 engines and require matched bushings and bearings for proper installation.

Wide Taper Rod – Direct Injection Engines

As Caterpillar transitioned the 3406 line into direct injection technology, the connecting rods evolved as well. The wide taper rod design is stronger, offering greater durability under high compression ratios and heavy-duty applications. This is the go-to rod for modernized 3406 engines that rely on direct fuel injection for improved efficiency and cleaner combustion.

Connecting Rod Bolts & Nuts

Every connecting rod is secured to the crankshaft using high-strength bolts and lock-tightened nuts. These fasteners must withstand thousands of pounds of pressure with every combustion cycle.

• Rod Bolts: Each connecting rod requires two bolts. These are manufactured with heat-treated steel to ensure strength and fatigue resistance. Regular replacement of bolts is recommended during rod servicing to avoid bolt stretch or failure.

• Rod Nuts: Used with the rod bolts to hold the cap securely in place. Designed with precision threads and hardened construction to maintain torque specifications.

Connecting Rod Bushings

Bushings provide the pivoting surface between the small end of the rod and the piston pin. Over time, bushings wear out due to constant oscillation and high operating temperatures. Diesel Pro Power supplies bushings matched to each rod design:

• Straight Rod Bushings: For pre-combustion style straight rods.

• Narrow Taper Bushings (6°): Designed to fit the small end of narrow taper rods.

• Wide Taper Bushings: Engineered for direct injection wide taper rods, with wider contact surfaces for strength under heavy loads.

Each bushing is manufactured from durable alloys and machined to exact tolerances, ensuring proper oil clearance and lubrication flow.

Connecting Rod Bearings for Caterpillar 3406

The big end of the connecting rod uses replaceable bearings to ride smoothly on the crankshaft journal. These precision-engineered shells protect both the crankshaft and the rod from direct metal-to-metal contact. Bearings are available in standard sizes as well as multiple oversizes to match crankshaft conditions after machining.

Standard Bearings

• Narrow Bearings: Used in older pre-combustion rods.

• Wide Bearings: Used in direct injection rods with wider bearing surfaces.

Oversize Bearings

When a crankshaft has been reground during an overhaul, oversized bearings are required to restore proper clearance. Diesel Pro Power offers oversize bearings in .010", .025", and .050" increments. These ensure that no matter the wear or machining performed on your crankshaft, you can achieve proper oil film clearance and maintain engine reliability.

Why Connecting Rod Variations Matter in the Caterpillar 3406

The Caterpillar 3406 family evolved significantly over its production life. Early pre-combustion chamber versions used different connecting rod geometries compared to later direct injection designs. Choosing the correct rod and bearing combination is critical because:

• Incorrect taper matching can cause uneven bearing wear and rod misalignment.

• Mismatched bushings can result in piston pin scoring or seizure.

• Improper bearing clearance leads to oil starvation, overheating, or catastrophic rod failure.

By stocking straight rods, narrow taper rods, and wide taper rods along with the correct bushings and bearings, Diesel Pro Power ensures you can service any version of the 3406 engine family.

Technical Benefits of OEM-Quality Rod Components

• Precision Machining: Ensures exact fit between rod, piston pin, and crankshaft.

• High-Strength Alloys: Designed to endure high combustion pressures and prevent fatigue cracking.

• Heat Treatment: Provides durability and resistance to wear at high operating temperatures.

• Matched Components: Rods, bolts, bushings, and bearings are engineered to work together as a complete system.

Applications of the Caterpillar 3406 Connecting Rod

The 3406 engine is one of Caterpillar’s most widely used powerplants, found in:

• On-highway trucks (freight hauling, vocational trucks)

• Construction equipment (bulldozers, graders, loaders)

• Marine engines (commercial vessels, workboats)

• Industrial applications (generators, pumps, drilling rigs)

Reliable connecting rods and bearings are vital in all these environments, where downtime translates directly into lost revenue.

Why Buy Caterpillar 3406 Connecting Rod Parts from Diesel Pro Power

• 40,000+ Satisfied Customers Worldwide – Trusted by fleets, ship operators, and repair shops across the globe.

• OEM-Quality Fit & Performance – Every rod, bearing, bushing, and bolt meets or exceeds original Caterpillar specifications.

• Fast Global Shipping – Whether you need a single bearing or a full set of rods, Diesel Pro delivers quickly to minimize downtime.

• Dedicated 3406 Catalog – Our catalog is organized by engine model, so you can order with confidence knowing each part fits your specific 3406.

• Expert Technical Support – Our team assists with identifying correct rod styles (straight, narrow taper, wide taper) and matching bearings for any rebuild scenario.