The right tandem axle trailer springs deliver smoother rides, improved stability, and longer-lasting suspensions for 3,500 lb trailers. This guide highlights five top options designed to replace SW4B/SW5 style springs with U-bolt and hanger kits, emphasizing capacity, durability, and installation details to help you choose confidently.
| Product | Capacity Per Spring | Eye-to-Eye | Leaf Count | U-Bolt Kit |
|---|---|---|---|---|
| SEHNSUCHT 4 Leaf Replacement | 1,750 lb | 25-1/4 in | 4 leaves | |
| Aeagle 25-1/4 4-Leaf | 1,750 lb | 25-1/4 in | 4 leaves | |
| dreamdragon Tandem Kit | 1,750 lb | 25-1/4 in | 4 leaves | |
| SEHNSUCHT SW5 Replacement | 3,000 lb | 25-1/4 in | 5 leaves | |
| LIBRA 3500lb Suspension Kit | 1,750 lb | 25-1/4 in | 4 leaves |
The following selections emphasize compatibility with 3,500 lb trailer axles, standard eye-to-eye measurements, and complete installation kits that include U-bolts, tie plates, and hanger components. Each entry is designed to replace SW4B or SW5 configurations while offering corrosion resistance and straightforward installation.
SEHNSUCHT 4 Leaf Replacement Kit for SW4B
Product overview: This kit features four leaf springs with a 1,750 lb capacity per spring, suitable for standard 3,500 lb trailer axles. Eye-to-eye length is 25-1/4 inches, free open height is 3 inches, and leaf width is 1-3/4 inch with 5/16 inch leaf thickness. The set includes two bushings pre-installed for each spring and a U-bolt kit. Note: ensure horizontal nut tightening for proper operation. Designed to replace SW4B, the springs are made from heavy-duty carbon steel with anti-rust coating for corrosion resistance and longevity. U-bolt kit contents: two 2-3/8″ axle-ready kits (2 x 5-1/2″ U-bolts, 1/2″ diameter; 2 tie plates; 8 hex nuts). Installation aligns with standard tandem trailer axles.
Key considerations: corrosion resistance is enhanced by the coating, but care should be taken during assembly to avoid misalignment. Users should verify axle diameter and leaf spring mounting hardware compatibility with their trailer model.
Aeagle 25-1/4″ 4-Leaf Spring Kit
Overview: Aeagle’s 4-leaf springs provide 1,750 lb per spring capacity for a 3,500 lb axle setup. Eye-to-eye length is 25-1/4 inches with a 3 inch free open height and 1-3/4 inch leaf width. Each spring uses 9/16 inch bushings, with two bushings installed. The kit includes four double-eye springs and a complete U-bolt kit for 2-3/8″ round axles, plus tie plates and hex nuts for 1-3/4″ leaf springs. Horizontal nut tightening is recommended to ensure proper seating and performance.
Considerations: The kit is designed for SW4B compatibility and requires a 2-3/8″ diameter axle. Ensure the trailer’s current hanger and equalizer components align with included parts for a clean install.
dreamdragon Tandem Kit With U-Bolts & Hangers
Overview: Each leaf spring is rated at 1,750 lbs, suitable for standard 3,500 lbs trailers. The kit features a 25-1/4″ eye-to-eye length, 3″ free open height, and 1-3/4″ leaf width. It includes a U-bolt set for 2-3/8″ diameter axles (4 x 5-1/2″ long U-bolts, 1/2″ diameter), along with 2 tie plates and 8 hex nuts. The design aims for smooth operation and enhanced stability, with corrosion resistance from protective coatings on the steel components.
Notes: When installing, ensure the installation surface is clean and free of debris to avoid binding. Verify compatibility with existing hangers and equalizers before mounting.
SEHNSUCHT SW5 Replacement 5-Leaf Kit
Overview: This replacement set is designed for 5-leaf springs, offering a 3,000 lb capacity per spring to suit 5,200–6,000 lb axle assemblies. Eye-to-eye length remains 25-1/4 inches with a 3 inch free open, 1-3/4 inch leaf width, and 9/16 inch bushings. The “SW5″ designation indicates compatibility with larger tandem setups, and the kit includes two U-bolt assemblies for 3” diameter axles plus tie plates and hex nuts. As with other kits, horizontal nut tightening is essential for optimal performance.
Considerations: Higher load capacity means closer attention to axle and frame clearance. Ensure the trailer’s current hardware can accommodate the larger 5-leaf configuration and the included hanger components.
LIBRA 3500lb Tandem Suspension Kit
Overview: This LIBRA kit delivers 1,750 lb per spring for 3,500 lb axles, with an eye-to-eye length of 25-1/4 inches and a free open height of 3 inches. The leaf width is 1-3/4 inch, and the set uses 9/16 inch bushings with nylon bushings installed for smoother action. It includes a 3,500 lb axle U-bolt kit compatible with 2-3/8″ round axles, along with tie plates and hex nuts. The kit is positioned as a SW4B replacement option and emphasizes a corrosion-resistant finish for longevity.
Notes: Nylon bushings can offer quieter operation and softer reception of shocks. Confirm axle diameter and mounting hardware compatibility with your trailer before purchasing.
Buying Guide: Key Considerations For Tandem Axle Trailer Springs
- Load capacity: Match the per-spring rating to your trailer’s gross weight. For a typical 3,500 lb axle, 1,750 lb per spring is common, but heavier setups may require 3,000 lb per spring options.
- Eye-to-eye length: The standard 25-1/4 inches fits many SW4B/SW5 configurations. Verify your trailer’s measured length to ensure a proper fit.
- Leaf count and width: More leaves provide greater load distribution and resistance to sag. Ensure leaf width (usually 1-3/4 inch) matches frame clearance and hanger spacing.
- Bushing type and diameter: Common 9/16 inch bushings with horizontal nut tightening help maintain alignment. Nylon bushings can reduce noise and wear over time.
- U-bolt and hanger kit contents: A complete kit with four U-bolts, tie plates, and nuts simplifies installation. Confirm compatibility with your axle diameter (2-3/8″ is common).
- Corrosion resistance: Look for anti-rust coatings or protective finishes suited to your operating environment, especially if the trailer is exposed to salt or humid conditions.
- Compatibility with existing hardware: Ensure the springs align with your trailer’s current hangers, equalizers, and shackles to avoid additional modification costs.
- Installation considerations: Horizontal nut tightening is a recurring requirement. Follow torque recommendations and recheck alignment after initial test runs.
- Warranty and service life: Consider brands offering warranties or documented service life expectations to gauge long-term value.