3500 lb Trailer Axle Kit – 1 Brake Axle + 1 Idler Axle, Springs & U-Bolts – 7K Capacity

3500 lb Trailer Axle Kit – 1 Brake Axle + 1 Idler Axle, Springs & U-Bolts – 7K Capacity

Product Description

Build or upgrade your tandem-axle trailer with a practical combination of braking performance, durable suspension components, and heavy-duty axle construction.

The 3500 lb Tandem Trailer Axle Kit includes one 3,500 lb electric brake axle and one 3,500 lb idler axle, providing a combined axle capacity of up to 7,000 lbs.

The kit also includes four 1,750 lb 4-leaf double-eye springs and two U-bolt kits, providing the primary axle and spring components required for a compatible tandem-axle trailer setup.

The axle assemblies feature durable steel construction, greaseable spindle components, and an underslung spring-seat configuration, with the spring seats positioned below the axle tube to help maintain a lower trailer deck and ride height.

Available in multiple Hub Face / Spring Center configurations to fit different trailer applications.

Key Features

• 3,500 lb Capacity Per Axle
• Up to 7,000 lb Combined Axle Capacity
• 1 × Electric Brake Axle
• 1 × Idler Axle
• 5 × 4.5" Bolt Pattern
• Includes 4 double-eye leaf springs
• 1,750 lb Spring Capacity Each
• Heavy-duty 4-leaf spring design
• Includes 2 complete U-bolt kits
• Greaseable spindle design for convenient maintenance
• Underslung spring-seat configuration
• Durable steel axle construction
• Multiple Hub Face / Spring Center sizes available
• Designed for compatible tandem-axle trailer applications

What's Included

Trailer Axles

• 1 × 3,500 lb Electric Brake Axle
• 1 × 3,500 lb Idler Axle

The electric brake axle provides braking capability when connected to a compatible trailer brake controller and wiring system.

The idler axle is equipped with idler hubs and does not include electric brake assemblies.

Leaf Springs

• 4 × 1,750 lb Double-Eye Leaf Springs
• 4-Leaf Design

The four double-eye springs are designed for compatible tandem-axle suspension installations.

U-Bolt Kits

• 2 × U-Bolt Kits

The included U-bolt hardware is used to secure the axles to the leaf springs.

Important Product Note

Suspension Hanger Kit is NOT Included

This kit does not include:

• Tandem Hanger Kit
• Equalizers
• Shackles
• Hanger Brackets
• Other Suspension Mounting Hardware

These components must be purchased separately if required for your trailer installation.

Technical Specifications

Available Hub Face / Spring Center Sizes

Choose the appropriate axle size for your trailer before ordering.

Hub Face

Hub Face is the distance from one wheel-mounting surface to the other.

Spring Center

Spring Center is the distance between the centerlines of the two spring seats.

Always measure your existing axle or trailer carefully before selecting a size.

Electric Brake + Idler Configuration

This tandem axle kit combines:

1 × Electric Brake Axle + 1 × Idler Axle

The electric brake axle provides trailer braking capability when properly connected to a compatible brake controller and electrical system, while the second axle uses idler hubs without electric brake assemblies.

This combination provides a practical solution for compatible tandem-axle trailer builds and replacement applications.

3,500 lb Axle Capacity

Each axle is rated for 3,500 lbs, giving the two-axle combination a total axle rating of up to:

7,000 lbs

Actual trailer capacity is determined by the complete trailer design and the rating of the lowest-capacity component in the system.

4-Leaf Double-Eye Springs

The kit includes:

4 × 1,750 lb 4-Leaf Double-Eye Springs

The double-eye design provides mounting eyes at both ends of each spring for use with compatible tandem suspension hardware.

Greaseable Spindle Design

The axle assemblies feature greaseable spindle components to provide convenient access for routine bearing lubrication and maintenance.

Regular bearing inspection and lubrication are recommended as part of normal trailer maintenance.

Underslung Spring Configuration

The spring seats are positioned below the axle tube.

This underslung configuration can help maintain a lower trailer deck and ride height compared with configurations where the springs are mounted above the axle.

Compatible Trailer Applications

Suitable for many compatible light-duty tandem-axle trailers, including:

• Utility Trailers
• Cargo Trailers
• Boat Trailers
• ATV Trailers
• Motorcycle Trailers
• Lawn & Landscape Trailers
• Car Haulers
• Enclosed Trailers
• Other Compatible Tandem-Axle Trailers

Frequently Asked Questions

Q1: What is included in this 3.5K tandem axle kit?

The kit includes:

• 1 × 3,500 lb Electric Brake Axle
• 1 × 3,500 lb Idler Axle
• 4 × 1,750 lb 4-Leaf Double-Eye Springs
• 2 × U-Bolt Kits

Suspension hanger components are not included.

Q2: Are both axles equipped with electric brakes?

No.

This kit includes:

1 Electric Brake Axle + 1 Idler Axle

Only one axle is equipped with electric brake assemblies. The idler axle does not include brake assemblies.

Q3: What is the total capacity of the tandem axle kit?

Each axle is rated for 3,500 lbs, providing a combined axle rating of up to 7,000 lbs.

Actual trailer capacity depends on the complete trailer structure and the ratings of all installed components.

Q4: What bolt pattern does the axle use?

The axle uses a:

5 × 4.5" Bolt Pattern

Always verify your wheel bolt pattern before purchasing.

Q5: What Hub Face / Spring Center sizes are available?

Available configurations are:

• 73" Hub Face / 58" Spring Center
• 89" Hub Face / 74" Spring Center
• 95" Hub Face / 80" Spring Center

Please measure your existing axle or trailer before selecting a size.

Q6: What does Hub Face / Spring Center mean?

Hub Face is the distance between the two wheel-mounting surfaces.

Spring Center is the distance between the centerlines of the two spring seats.

These dimensions are important for proper axle fitment.

Q7: Are leaf springs included?

Yes.

The kit includes:

4 × 1,750 lb 4-Leaf Double-Eye Springs

Q8: Are U-bolt kits included?

Yes.

The package includes 2 U-bolt kits for securing the axles to the leaf springs.

Q9: Is the tandem suspension hanger kit included?

No.

The following suspension mounting components are not included:

• Tandem Hanger Kit
• Equalizers
• Shackles
• Hanger Brackets
• Other Suspension Mounting Hardware

Q10: Are the spring seats mounted above or below the axle?

The spring seats use an underslung configuration, meaning the spring seats are positioned below the axle tube.

Q11: What trailers can this axle kit be used on?

The kit is suitable for many compatible tandem-axle trailer applications, including:

• Utility Trailers
• Cargo Trailers
• Boat Trailers
• ATV Trailers
• Motorcycle Trailers
• Lawn & Landscape Trailers
• Car Haulers
• Enclosed Trailers

Always verify axle dimensions, spring-center dimensions, bolt pattern, suspension configuration, wheel compatibility, and trailer capacity requirements before ordering.

Installation Notes

Before installation, verify:

• Correct Hub Face measurement
• Correct Spring Center measurement
• Wheel bolt pattern
• Trailer suspension configuration
• Spring and hanger compatibility
• Wheel and tire capacity
• Brake controller and wiring compatibility
• Trailer frame and suspension capacity

Professional installation is recommended when replacing or installing trailer axles.