Answering the common question “which 4-leaf trailer spring should I buy?” this guide highlights five well-matched options that balance load capacity, durability, and compatibility. Ideal for small utility trailers, boat haulers, or cargo trailers, these springs are designed for easy replacement and long service life. The top picks cover a range from 1400–3500 lb per spring, helping you choose based on axle capacity and trailer type. The buyer-friendly table below summarizes key details for quick comparison.
| Product | Leaf Count | Capacity (per spring) | Length | Fitment |
|---|---|---|---|---|
| Dorman 929-1031 | 4 | 2000 lb | 26″ | Eye/Eye, 1 3/4″ width |
| Magorfas 4 Leaf SW4B | 4 | 1750 lb | 25-1/4″ | SW4B, 3500 lb axle |
| Magorfas 4 Leaf SW4B (Single) | 4 | 1750 lb | 25-1/4″ | SW4B, 3500 lb axle |
| Magorfas 4 Leaf SW4 | 4 | 2500 lb | 25-1/4″ | SW4, 5000 lb axle |
| RV MURTS Kit | 4 | 1750 lb (per spring) | 25-1/4″ | SW4B, 3500 lb tandem |
| Youxmoto Pair | 4 | 1750 lb | 25-1/4″ | SW4B |
Dorman 929-1031 Utility Trailer Leaf Spring
Type: Eye/Eye, 1 3/4″ width, 26″ length, 4 1/4″ arch, 4 Leaf, 2000 lb capacity. The design mirrors original leaf springs, enabling a direct replacement for trailers that experience overloading, damage, or corrosion. Durable construction aims for reliable performance over time.
Best for: Trailer owners replacing aging springs on standard utility trailers or small enclosed units. This option is especially suitable when aiming for a straightforward, bolt-on swap with minimal modification. Cautions: Check axle and spring alignment before installation to avoid misfit or binding.
Magorfas 4 Leaf SW4B 1750 lb Per Spring (Set 2)
Capacity: 1750 lb per spring (3500 lb per axle). 25-1/4″ eye-to-eye, 1-3/4″ leaf width, 5/16″ leaf thickness, and 9/16″ bushing diameter. This set uses 60Si2Mn manganese steel with corrosion-resistant two coats of paint. Fits SW4B trailers and is intended for heavier loads within its rated range.
Best for: Trailers that operate under moderate-to-heavy loads on SW4B axles. Better for those needing a robust, manganese steel solution with corrosion resistance. Caution: Ensure proper load rating alignment to avoid undersizing for your trailer.
Magorfas 4 Leaf SW4B Single Spring 1750 lb (Set 2)
Specs mirror the dual-set with eye-to-eye length of 25-1/4″, 3″ free open, 1-3/4″ leaf width, 9/16″ bushing diameter, and 5/16″ leaf thickness. Fitment SW4B and 3500 lb axle compatibility, with 1750 lb per spring rating. No-hassle corrosion protection through two paint coats.
Best for: Users seeking a paired set for a single axle SW4B trailer or replacing an existing second spring. Choose this if you want matched pairs for balanced suspension. Limitation: Verify squarely that the set matches your specific axle and hanger design.
Magorfas 4 Leaf SW4 2500 lb Per Spring (Set 2)
Capacity: 2500 lb per spring (5000 lb axle). Eye-to-eye length 25-1/4″, free open 3″, leaf width 1-3/4″, 9/16″ bushing diameter, leaf thickness 3/8″. The kit uses manganese steel with corrosion-protective two-coat finish and suits SW4 trailers with higher load demands.
Best for: Heavier load scenarios on SW4 axles where 5000 lb gross capacity is anticipated. Better for: longer lifespan under repeated heavy-duty use. Caution: The higher stiffness may affect ride smoothness on rough roads; ensure vehicle weight distribution supports the higher rating.
RV MURTS 4 Leaf Trailer Spring Kit
Includes: 4-leaf springs, U-bolts, hangers, and shackle kit for a 3,500 lb trailer axle tandem suspension. Each spring offers 1,750 lb capacity per spring. The kit variant is designed for SW4B compatibility with multiple reference numbers for ease of identification. The bundle approach supports a complete axle swap or refresh.
Best for: Trailer owners seeking an all-in-one replacement kit that includes hangers, shackles, and U-bolts. Avoid this if you need only springs without accessories or have a different axle style, as kit contents are tuned to SW4B tandem configurations.
Youxmoto 4 Leaf SW4B Pair with Bushings
Profile: 25-1/4″ eye-to-eye, 3″ free open, 1-3/4″ leaf width, 5/16″ leaf thickness, 9/16″ bushing diameter. 1750 lb per spring, suitable for 3,500 lb trailers (SW4B). The set emphasizes direct replacement with mounting bushings included, ensuring correct fitment and easier installation.
Best for: Buyers wanting a straightforward, ready-to-install pair for SW4B trailers with included bushings. Choose this if you prefer a packaged solution that minimizes compatibility guesswork. Caution: Confirm your axle and hanger dimensions before ordering to ensure a precise match.
Buying Guide: Key Purchase Considerations
- Trailer axles and capacity: Match per-spring capacity to your trailer’s axle rating to avoid undersized or oversized springs.
- Fitment compatibility: Confirm eye-to-eye length, width, and bushing diameter match your existing hardware (SW4B vs SW4, etc.).
- Material and finish: Manganese steel (60Si2Mn) offers strength and durability; two coats of paint improve corrosion resistance.
- Replaceable kit vs. springs only: Kits with U-bolts, hangers, and shackles simplify installation but may include items you already own.
- Single vs. paired sets: For dual-axle trailers, consider sets that provide two springs per side to balance load.
- Installation considerations: Proper alignment, torque on bolts, and verifying no binding under full suspension travel reduce service issues.
- Weight distribution: Higher-capacity springs can affect ride quality on light-duty trailers; ensure the load profile justifies the upgrade.
FAQ
- What is a leaf spring’s main purpose for a trailer?
- How do I know which spring capacity to choose?
- Can I replace just one spring, or should I replace pairs?
- What does eye-to-eye length mean, and why does it matter?
- Are these springs compatible with all trailer brands?
- What maintenance should I perform after installing new springs?
Direct answers: Leaf springs support weight, distribute load, and absorb road shocks. Capacity should align with axle rating and expected cargo. Replacing in pairs maintains balance; eye-to-eye length must match the existing mounting points. Compatibility depends on axle type (SW4, SW4B) and hanger style. After installation, check for proper alignment and retorque bolts after a brief break-in period. Regular inspection for corrosion or cracked leaves extends service life.