Rockwell American 3,500 lb Idler Trailer Axle Kits

Rockwell American 3,500 lb Idler Trailer Axle Kits

Build, repair, or upgrade your trailer with a Rockwell American 3,500 lb Idler Trailer Axle Kit designed for dependable performance on utility trailers, cargo trailers, landscape trailers, boat trailers, ATV trailers, and other light-duty single-axle applications.

Choose from Axle Only, Suspension Kit, Build Kit, or Running Gear Kit configurations to match your project. Whether you are replacing a damaged axle, rebuilding worn suspension components, or assembling a trailer from the frame up, each package provides a practical combination of compatible axle and running gear components.

Rockwell American axles are part of the Dexter family of trailer axle brands and feature Posi-Lube® greaseable spindles, a cambered axle beam, pre-installed idler hubs, and a durable powder-coated finish. Multiple hub face and spring center sizes are available to fit many common trailer frame configurations.

Made in America. Free shipping in the lower 48 states.

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Compare Kit Options

Select the trailer axle package that best matches your repair, replacement, or new trailer build requirements.

← Swipe left/right to compare all kit options →

Axle Only: Includes one Rockwell American 3,500 lb idler axle with pre-installed idler hubs, Posi-Lube® spindles, spring seats, and brake mounting flanges. Best for replacing an existing axle while reusing compatible suspension components.

Suspension Kit: Includes the idler axle, double-eye leaf springs, and a U-bolt kit. This package is well suited for replacing the axle and primary suspension components while retaining an existing hanger system.

Build Kit: Includes everything in the Suspension Kit plus a complete single-axle hanger kit. Ideal for new trailer fabrication, frame-up builds, and complete suspension replacement.

Running Gear Kit: Includes everything in the Build Kit plus matching 15″ wheels and ST205/75R15 radial trailer tires. This is the most complete configuration for new trailer construction or major running gear replacement.

Axle Only and Suspension Kit configurations are commonly selected for repairs and partial upgrades. Build Kit and Running Gear Kit configurations are better suited for complete trailer builds and major rebuilds.

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Choose Your Axle Size (Hub Face / Spring Center)

Select the hub face (HF) and spring center (SC) measurements that match your trailer frame and suspension setup. Correct measurements help provide proper wheel positioning, spring alignment, tire clearance, and overall trailer fitment.

Hub Face (HF): Measure from the wheel-mounting surface on one hub to the wheel-mounting surface on the opposite hub.

Spring Center (SC): Measure from the center of one spring seat to the center of the opposite spring seat.

Important: Measure your existing axle before ordering. Do not select an axle based only on trailer deck width, frame width, fender spacing, or overall trailer width.

Not sure which axle size you need? Read our How to Measure a Trailer Axle Guide or contact us, and we’ll help verify your measurements before you order.

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Why Choose Rockwell American?

• Made in America: Rockwell American axles are manufactured in the USA for dependable fitment and towing performance.
• Dexter Family of Brands: Rockwell American is supported by one of the most recognized names in the trailer axle industry.
• 3,500 lb Axle Capacity: Well suited for many utility, cargo, landscape, boat, ATV, and light equipment trailer applications.
• Posi-Lube® Spindles: Integrated grease fittings simplify routine bearing lubrication without removing the hubs.
• Cambered Axle Beam: Designed to support proper wheel tracking and tire contact when the axle is loaded.
• Powder-Coated Finish: Provides a durable protective coating for regular road and trailer use.
• Brake-Ready Design: Pre-welded 4-bolt brake mounting flanges allow compatible electric brakes to be installed later.

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Idler Axle with Brake-Ready Flanges

This axle is supplied as an idler axle, meaning it does not include electric brake assemblies or hub-and-drum assemblies. It includes idler hubs for free-rolling trailer applications.

Pre-welded 4-bolt brake mounting flanges make it possible to add compatible electric trailer brakes later. Additional brake assemblies, hub-and-drum assemblies, wiring, and brake-control components are required for conversion.

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Posi-Lube® Spindle System

Rockwell American Posi-Lube® spindles include built-in grease fittings that direct lubricant through the spindle and into the hub assembly. This design makes routine bearing lubrication more convenient and helps support dependable hub and bearing performance.

Posi-Lube® does not eliminate the need for periodic hub inspection, bearing service, seal replacement, or proper trailer maintenance.

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Common Applications

• Utility Trailers
• Cargo Trailers
• Landscape Trailers
• Boat Trailers
• ATV and UTV Trailers
• Small Equipment Trailers
• Farm and Property Trailers
• General-Purpose Trailers
• Custom Single-Axle Trailer Builds

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Fitment and Capacity Notes

• Verify the selected hub face and spring center measurements before ordering.
• Confirm the hub bolt pattern matches your trailer wheels.
• Verify wheel, tire, suspension, and trailer frame ratings before loading.
• Confirm adequate tire, fender, and frame clearance throughout the suspension’s full range of movement.
• The axle’s 3,500 lb rating does not determine trailer payload or GVWR by itself.
• Final trailer capacity is limited by the lowest-rated component in the complete trailer system.
• Hanger installation and welding should be completed by a qualified trailer fabricator when applicable.

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Frequently Asked Questions

What is included with each kit configuration?

Axle Only includes the Rockwell American idler axle. The Suspension Kit adds double-eye leaf springs and a U-bolt kit. The Build Kit adds a single-axle hanger kit. The Running Gear Kit adds matching wheels and ST205/75R15 radial trailer tires.

How do I measure my trailer axle?

Measure the hub face from one wheel-mounting surface to the opposite wheel-mounting surface. Measure the spring center from the center of one spring seat to the center of the opposite spring seat. Visit our How to Measure a Trailer Axle Guide for additional help.

Can electric brakes be added later?

Yes. These idler axles include pre-welded 4-bolt brake mounting flanges. Compatible brake assemblies, hub-and-drum assemblies, wiring, and brake-control components must be purchased separately.

What are Posi-Lube® spindles?

Posi-Lube® spindles use an integrated grease fitting and internal lubrication passage to help direct grease into the hub assembly during routine maintenance.

Does the axle include springs and mounting hardware?

Only the Suspension Kit, Build Kit, and Running Gear Kit include springs and U-bolt hardware. The hanger kit is included only with the Build Kit and Running Gear Kit.

Does the Running Gear Kit include wheels and tires?

Yes. The Running Gear Kit includes matching 15″ wheels and ST205/75R15 radial trailer tires in addition to the axle and suspension components.

What trailers commonly use this axle?

These 3,500 lb idler axle kits are commonly used on utility, cargo, landscape, boat, ATV, UTV, and other light-duty single-axle trailers.

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Resources & Downloads

• Rockwell American Axle Service Guide
• Trailer Hanger Kit Spacing Guide
• How to Measure a Trailer Axle
• Johnson Trailer Parts YouTube Channel

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Installation Video

Watch our video for helpful information about trailer axle measurements, installation, suspension setup, and replacement axle selection.

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Need Help?

Need help selecting the correct axle size, bolt pattern, or kit configuration? Our knowledgeable team can help verify your measurements and fitment before you order.

Call or Text: (602) 292-9690
Email: sales@johnsontrailerparts.com