When choosing a 3500 lb trailer leaf spring kit, focus on fit for round axles, correct eye-to-eye length, and a durable build. This guide highlights five kits that consistently align with SW4B-compatible setups and offer reliable corrosion resistance. Ideal buyers include weekend trailering enthusiasts, small-business haulers, and DIY trailer owners seeking straightforward replacement parts. Below, you’ll find a quick comparison, product details, and practical buying tips to help select the best option for your trailer.
| Product | Axle Type | Leaf Count | Eye To Eye | Notes |
|---|---|---|---|---|
| SEHNSUCHT 4 Leaf Replacement Kit | Round | 4 | 25-1/4″ | Includes U-bolts and hanger kit; note on horizontal nut tightening |
| Aeagle 4 Leaf 1750lb Kit (SW4B) | Round | 4 | 25-1/4″ | Comprehensive hanger and U-bolt set |
| AEagle 25-1/4″ 4-Leaf Kit (SW4B) | Round | 4 | 25-1/4″ | Includes tandem hanger kit for 1-3/4″ springs |
| Youxmoto 3500lb Suspension Kit | Round | 4 | 25-1/4″ | U-bolts and hanger set included |
| Magorfas Tandem 4-Leaf Set | Round | 4 | 25-1/4″ | Coated for corrosion resistance; fits SW4B |
SEHNSUCHT 4 Leaf Replacement for SW4B Trailer
Features: 4 leaves per spring; each spring supports 1,750 lbs, totaling 3,500 lbs for standard trailers. Eye-to-eye length is 25-1/4″, with a 3″ free open and leaf width of 1-3/4″. Bushing diameter is 9/16″, with 2 bushings installed per spring. Includes 4-leaf springs, 2 U-bolts per spring, and hanger components. Note: tighten the nut horizontally to ensure proper performance.
Best for: Owners replacing a SW4B-equipped setup who want a complete kit with U-bolts and hangers. Why chosen: straightforward compatibility, heavier-duty carbon steel construction, and corrosion resistance from anti-rust coating.
Caution: Improper horizontal nut tightening can affect performance; follow the installation note for best results.
Aeagle 4 Leaf 1750lb Capacity SW4B Kit
Features: 2 x 4-leaf double-eye springs; 3,500 lbs axle U-bolt kit for 2-3/8″ round axles. Includes 4 x 5-1/2″ U-bolts, 1/2″ diameter, with 2 x tie plates for 1-3/4″ leaf springs and 8 x 1/2″-20 hex nuts. Tandem hanger kit contains 2 x EQ-E1 equalizers, 6 x tall hangers, 8 x shackle straps, and related bolts and locknuts. Each spring is rated at 1,750 lbs (per spring) for a total capacity of 3,500 lbs. Note: tighten the nut horizontally as advised.
Best for: Trailer owners needing a complete, round-axle replacement with a full hanger and U-bolt set. Why chosen: comprehensive hardware pack and compatible dimensions for SW4B replacements.
Caution: Not compatible with square axles; verify axle type before purchase.
AEagle 25-1/4″ 4-Leaf SW4B Kit
Features: Replaces SW4B; suitable for round axles only. Each spring delivers 1,750 lbs capacity, totaling 3,500 lbs for trailers. Eye-to-eye length 25-1/4″, free open 3″, leaf width 1-3/4″, 4 leaves, 9/16″ bushings with 2 per spring. Includes 4 springs, 3,500 lbs axle U-bolt kit (2-3/8″ dia round axles), 8 x 1/2″-20 hex nuts, 2 x 3″ tall hangers and 2 x 2.1″ tall hangers, plus shackle bolts and locknuts.
Best for: Those replacing a SW4B with a robust, all-in-one kit that includes complete hanger components. Why chosen: reliable dimensions and a sturdy coating for corrosion resistance.
Caution: Verify axle diameter before ordering; data specifies 2-3/8″ round axles only.
Youxmoto 3500lb Suspension Kit
Features: 4-leaf springs with 1,750 lb per-spring capacity, designed for 3,500 lb trailers. Eye-to-eye length 25-1/4″, free open 3″, leaf width 1-3/4″, bushings 9/16″ with 2 installed per spring. Kit includes 4 U-bolts (5-1/2″ long, 1/2″ dia.), 2 tie plates for 1-3/4″ leaves, and 8 hex nuts. Includes tandem hanger components for a complete install. Note: horizontal tightening of nuts is required.
Best for: DIY installers who want a complete, value-packed kit for SW4B-equivalent configurations. Why chosen: straightforward contents and compatible hardware for a 3,500 lb system.
Caution: Ensure your axle is round and 2-3/8″ diameter to avoid fit issues.
Magorfas Tandem 4-Leaf Set
Features: 4 leaves per spring; 1,750 lb per leaf, total capacity 3,500 lbs. Eye-to-eye 25-1/4″, free open 3″, leaf width 1-3/4″, bushing dia 9/16″, leaf thickness 5/16″. Includes U-bolts, tie plates, and a complete hanger kit designed for SW4B, with additional corrosion-resistant coatings for long-lasting use.
Best for: Trailer owners seeking a corrosion-resistant kit with a full hanger and hardware package. Why chosen: robust steel construction and comprehensive accessories for a full replacement.
Caution: Check load rating to confirm the correct leaf spring selection for your trailer.
Buying Guide
What to check before buying: Confirm axle type (round vs square) and axle diameter (2-3/8″ is common). Verify eye-to-eye length (25-1/4″) and free open height (3″). Ensure leaf count matches your current setup (4 leaves for a 3,500 lb system). Look for corrosion resistance and included hardware (U-bolts, tie plates, hangers).
Material and durability: Springs in these kits are typically high-strength carbon steel with anti-rust coatings for better longevity in outdoor environments. Consider manganese steel options for higher durability in rough terrain.
Installation considerations: Horizontal nut tightening is emphasized across products to ensure proper clamping force and reduced looseness. If you’re replacing both springs and U-bolts, verify your mounting hardware compatibility with existing brackets and hangers.
Different configurations: If you need a tandem hanger setup, choose kits that include equalizers and shackle hardware. For single-axle trailers, ensure the kit corresponds to a 1-3/4″ leaf width and 9/16″ bushings.
FAQ
- What axle type is required for these kits? Most kits are designed for 2-3/8″ round axles; not all fit square axles. Check product notes before purchasing.
- What does “eye to eye” mean? It is the mounted length from the inner sides of the spring eyes, typically 25-1/4″ for these kits.
- Are U-bolts included? Yes, most kits include U-bolts and associated hardware for a complete replacement.
- Why is horizontal nut tightening recommended? It ensures proper clamping force and reduces movement that can affect performance.
- Can these kits fit a tandem axle? Some kits include tandem hangers and equalizers; verify the included hardware matches your trailer’s setup.
- What if I have a SW4B design? Most listed kits are SW4B-compatible and specify this in the features.