2 Pieces Replacement SW4B 4-Leaf Trailer Spring Kit - 1750lb Each

In this review the focus is on a practical trailer suspension replacement kit intended for standard 3,500lb single axles. The reviewer found it best for owners who need a direct SW4B swap with reliable load capacity and straightforward hardware included. The single biggest reason to buy is the matched 1,750lb capacity per spring and the complete set of u-bolts and hangers that make a one-stop replacement, delivering predictable ride support and corrosion-resistant construction for trailer use.

Key Features

• Load capacity: Each leaf spring is rated at 1,750lb, providing matched support for a 3,500lb axle and predictable towing stability.
• Exact fit dimensions: Eye-to-eye length of 25-1/4 in and 3 in free-open length help ensure a correct replacement for SW4B-style suspensions.
• Durable construction: Heavy duty carbon steel with anti-rust coating increases resistance to corrosion and extends service life in road and marine conditions.
• Complete hardware kit: Includes 4 u-bolts, tie plates, hangers, shackle straps and bolts so most swaps can be completed without sourcing extra parts.
• Bushing ready: Two 9/16 in bushings are installed per spring to simplify installation and reduce initial fitment effort.

Who It's For

This kit is aimed at trailer owners who need a like-for-like replacement for SW4B leaf springs on a single 3,500lb axle, including boat trailers and utility trailers that require matched spring capacity. Installers who prefer a packaged solution with u-bolts, tie plates, hangers and shackles will appreciate having the common fasteners included.

It is not ideal for heavy commercial trailers that exceed the rated axle capacity or for custom suspension setups that require non-standard eye-to-eye lengths or different leaf widths. Those seeking premium powder-coat finishes or custom spring rates should look elsewhere.

Pros & Cons

Pros

• Solid 1,750lb per spring rating provides proper support for a 3,500lb axle when installed as a pair.
• Comprehensive hardware pack reduces the need to hunt for matching u-bolts and hangers.
• Carbon steel construction with anti-rust coating improves longevity in wet and coastal environments.

Cons

• Some customers report missing parts in shipments, so verify all components on receipt.
• The nut tightening instruction (tighten horizontally) is important; incorrect tightening can affect performance and user experience.

Specifications

Our Verdict

This replacement kit is a practical, cost-effective choice for trailer owners seeking a direct SW4B swap with proven 1,750lb spring capacity and a full hardware set included. It offers durable carbon steel construction with anti-rust coating and simplifies most repairs, but buyers should inspect the kit on arrival for missing pieces and follow the horizontal nut tightening instruction for best results.

Frequently Asked Questions

Will these springs fit my 3,500lb trailer axle?
Yes, each spring is rated 1,750lb and the pair is intended for standard 3,500lb single axles when dimensions match.

Does the kit include all u-bolts and hangers needed?
The kit includes 4 u-bolts, tie plates, hangers, shackle straps and hardware, but inspect the shipment on receipt because some customers report missing parts.

Are bushings installed?
Yes, two 9/16 in bushings are installed per spring to simplify installation.