Best 4 Leaf Springs For Trailer: Compare 10 Replacement Options

#1 · Best Overall

1. Aeagle Complete Suspension Kit

Best for: Round-Axle Hanger Kit Bundle.

Why it ranks #1: Includes two 1,750-pound springs, U-bolts, tie plates, and a hanger kit; listed for SW4B and 2-3/8-inch round axles.

A complete single-axle hanger kit joins the springs and U-bolt hardware in this Aeagle package, bringing hangers and shackle straps into the same replacement set. Its four-leaf springs are rated at 1,750 pounds each for a 3,500-pound trailer axle.

The package lists two 3-inch hangers, two 2.1-inch hangers, four shackle straps, and an axle U-bolt kit with tie plates and nuts. That hardware breadth can reduce separate sourcing when replacing a single trailer axle suspension. The springs measure 25-1/4 inches long and 1.75 inches wide, and the listing specifies SW4B replacement. Fit is limited to 2-3/8-inch round axles; square axles are explicitly excluded. Electroplated coating is listed for rust protection.

Skip it if you have a square axle; this package is specified only for round axles, while Magorfas MFLS0007Q2 serves a 5,000-pound trailer spring application.

This Aeagle bundle suits a 3,500-pound trailer owner replacing SW4B-style suspension and seeking springs plus hangers, straps, and axle hardware together. Its stated fit is a 2-3/8-inch round axle, not a square beam.

Listed on Amazon as: AEagle 4 Leaf 1750lb Capacity Double Eye Spring for 3500lb Trailer Axle, 25-1/4" Length, 1.75" Width, 3" Free Open & U-Bolt & Hanger Kit, Suspension Kit Replaces SW4B, 2PCS

#2 · Best U-Bolt Kit

2. Aeagle U-Bolt Kit Pair

• Weight: 28.8 lb
• Package Dimensions: 28.4 x 12.2 x 4.9 in

Best for: Round-Axle SW4B Replacement.

Why it ranks #2: Pairs two 1,750-pound, 25-1/4-inch springs with U-bolts and tie plates for a 3,500-pound axle and 2-3/8-inch round axle.

The 60Si2Mn manganese-steel springs distinguish this Aeagle set, with the listing linking their elasticity and shock absorption to a smoother, steadier trailer ride. The pair is rated at 1,750 pounds per spring for a 3,500-pound axle.

Each four-leaf spring measures 25-1/4 inches long and 1.75 inches wide, and the package includes a U-bolt kit with tie plates and nuts. That combination can simplify a SW4B replacement on a 2-3/8-inch round axle by supplying spring and axle-mounting hardware together. The listing also specifies a 3-inch free opening and electroplated rustproof coating, supporting buyers checking dimensions and seeking corrosion protection. Its compatibility is explicitly limited to round rather than square axles.

Skip it if you need springs for a square axle; this set is specified only for round axles, while Magorfas MFLS0007Q2 is rated for a 5,000-pound trailer.

This Aeagle pair suits a 3,500-pound trailer owner replacing SW4B springs on a 2-3/8-inch round axle and wanting mounting hardware in the package. The round-axle restriction is central to fit.

Listed on Amazon as: Aeagle 25-1/4" 4-Leaf 1750lb Capacity Double Eye Spring for 3500lb Trailer Axle & U-Bolt Kit, 1.75" Width, 3" Free Open, Replaces for SW4B, 2PCS

#3 · Best Rust Protection

3. Youxmoto U-Bolt Suspension Kit

• Weight: 28.7 lb

Best for: 3500-Pound Axle Hardware Kit.

Why it ranks #3: Combines 1,750-pound springs for a 3,500-pound trailer with U-bolts and tie plates; the listed springs have an extra rust-proof coating.

A matched U-bolt package is the key distinction here: the pair of 1,750-pound, four-leaf springs comes with axle fasteners and tie plates, giving owners of a 3,500-pound round-axle trailer more of the suspension hardware in one kit.

The springs measure 25-1/4 inches eye to eye and 1-3/4 inches wide, with 9/16-inch eye IDs, while the included tie plates suit that spring width. Four 5-1/2-inch U-bolts, eight nuts, and the plates support a single-axle replacement workflow. The listing specifies a 2-3/8-inch round axle and SW4B fit, so this is a targeted combination rather than a universal axle kit. Its added rust-proof coating is intended to handle harsh environments.

Skip it if you have a square axle or a different axle diameter; this kit is specified for a 2-3/8-inch round axle.

Choose this Youxmoto kit for a 3,500-pound trailer owner replacing SW4B-style springs who wants U-bolts and tie plates included. Its stated axle boundary is a 2-3/8-inch round beam, not a square axle.

Listed on Amazon as: Youxmoto 3500lb Single Trailer Axle Suspension Kit 1750lb Leaf Springs & Ubolt Kit; Pair of Trailer Leaf Spring 4 Leaf Double Eye, 25-1/4" L, 1-3/4" Width, 9/16 Eye I.D

#4 · Best Spec Detail

4. Youxmoto Four-Leaf Pair

• Weight: 23.7 lb

Best for: Dimension-Specific SW4B Springs.

Why it ranks #4: Lists 25-1/4-inch eye-to-eye length, 1-3/4-inch width, 9/16-inch bushing diameter, and 1,750-pound capacity per spring.

Precise eye-to-eye and bushing dimensions make this Youxmoto pair useful for a close SW4B replacement match: it lists a 25-1/4-inch length, 1-3/4-inch width, and 9/16-inch bushing diameter for 3,500-pound trailers.

Each four-leaf spring is rated at 1,750 pounds and has a 3-inch free opening, 5/16-inch leaf thickness, and two installed bushings. These measurements give suspension replacers several points to compare with their existing setup before installation. The listing identifies SW4B compatibility and a 3,500-pound trailer application, while its added rust-proof coating is intended for harsh environments. This is a pair of springs rather than the U-bolt and tie-plate package found in some suspension kits.

Skip it if you want axle fasteners bundled with the springs; this package lists a pair of springs rather than U-bolts and tie plates.

This Youxmoto pair fits buyers replacing SW4B-style springs on a 3,500-pound trailer who value specified bushing and leaf dimensions. It does not list U-bolts, so account for mounting hardware separately.

Listed on Amazon as: Youxmoto Pair of Trailer Leaf Spring 4 Leaf Double Eye, 1750lbs Cap for 3500lbs Axle, 25-1/4" L, 1-3/4" Width, 9/16 Eye I.D (2 Bushings), Fits for SW4B

#5 · Best Hanger Kit

5. SEHNSUCHT Hanger Kit

• Weight: 37.9 lb
• Package Dimensions: 29 x 13 x 4.5 in

Best for: Complete SW4B Suspension Package.

Why it ranks #5: Includes two 1,750-pound springs and a U-bolt and hanger kit; listed spring dimensions include 25-1/4-inch length and 1-3/4-inch width.

A spring, U-bolt, and hanger package sets this SEHNSUCHT kit apart from spring-only listings, offering a broader collection of components for a single 3,500-pound trailer axle replacement. Each four-leaf spring is rated for 1,750 pounds.

The pair uses 25-1/4-inch eye-to-eye springs with 1-3/4-inch width, 9/16-inch bushings, and a 3-inch free opening. Those dimensions help buyers compare the springs with an SW4B setup, while the listed U-bolt and hanger kit can bring more replacement components into one installation workflow. The listing says each spring has two bushings installed and notes that nuts should be tightened horizontally. Its 3,500-pound axle application is the relevant capacity boundary.

Skip it if you are replacing only springs and do not need the listed U-bolt and hanger kit; SEHNSUCHT LS0002 lists springs without that broader hardware package.

Choose this SEHNSUCHT package for an SW4B-style, 3,500-pound single-axle replacement where springs, U-bolts, and hangers are useful together. Follow its horizontal nut-tightening instruction during installation.

Listed on Amazon as: 2 Pieces of Replacement for SW4B 4 Leaf Trailer Spring, 3500lb Single Trailer Axle Suspension Kit with 1750lb Capacity Double Eyes Leaf Springs, U-Bolt and Hanger Kit

#6

6. SEHNSUCHT Four-Leaf Pair

• Weight: 24.2 lb
• Package Dimensions: 28.3 x 12 x 4.8 in

Best for: 3500-Pound Spring-Only Pair.

Why it ranks #6: Offers two SW4B replacement springs rated at 1,750 pounds each, with 25-1/4-inch eye-to-eye length and 9/16-inch bushings.

A stated 3-inch free opening adds a useful fit dimension to this SEHNSUCHT pair of four-leaf springs, alongside its 25-1/4-inch length and 1,750-pound capacity per spring for a standard 3,500-pound trailer axle.

The 1-3/4-inch-wide springs have 9/16-inch bushing diameters, 5/16-inch leaf thickness, and two bushings installed per spring. Those measurements help owners compare the pair with an SW4B replacement before beginning installation. The listing identifies the springs as a match for that application and gives the per-spring capacity for assessing the intended axle class. Unlike a package listing U-bolts and hangers, this product is described as two springs, so hardware needs are a separate consideration.

Skip it if you need a full suspension hardware package; this listing specifies two springs, while SEHNSUCHT LS0004 includes U-bolts and hangers.

This SEHNSUCHT pair suits owners replacing SW4B springs on a standard 3,500-pound axle who can source any other needed components. Check the listed length, width, and bushing dimensions against the existing suspension.

Listed on Amazon as: SEHNSUCHT Trailer Leaf Spring, 4 Leaf 1750lb Capacity Double Eye Leaf Springs for 3500lb Trailer Axle, 25-1/4"L, 1.75" Width, 3” Free Open of Leaf Spring, Replace for SW4B, 2 Pieces

#7

7. Magorfas U-Bolt Pair

• Weight: 29.2 lb
• Package Dimensions: 29.2 x 12.7 x 5.6 in

Best for: 3500-Pound Springs With U-Bolts.

Why it ranks #7: Pairs two 1,750-pound springs with four 5-1/2-inch U-bolts, suiting buyers seeking replacement springs and axle hardware together.

Included U-bolts give this Magorfas pair an installation-oriented advantage over spring-only listings: the four-leaf double-eye springs are rated at 1,750 pounds each, and the kit includes four 5-1/2-inch U-bolts for a 3,500-pound trailer.

The springs are listed at 25-1/4 inches long and fit SW4B applications, while the included U-bolts measure 5-1/2 inches and have a 1/2-inch diameter. Having both springs and axle fasteners together can simplify sourcing for a single-axle replacement. The listed 1,750-pound capacity per spring establishes the intended 3,500-pound trailer class. The supplied facts do not name tie plates or hanger components, so buyers needing those parts should account for them separately.

Skip it if you need tie plates and hangers included as well as U-bolts; Aeagle AELS0004Q2 lists a broader axle hanger kit.

Pick this Magorfas set for a 3,500-pound trailer owner replacing SW4B springs who wants U-bolts included. The listing does not specify tie plates or hangers, so check what other parts your replacement requires.

Listed on Amazon as: Single Trailer Leaf Spring 4 Leaf Double Eye 1750 lbs Cap for 3500 lbs Axle Suspension & U-Bolt kit, 25-1/4" Length fits for SW4B – Set 2

#8

8. Magorfas 3500-lb Pair

• Weight: 24.3 lb
• Package Dimensions: 28.3 x 12 x 4.7 in

Best for: Simple 3500-Pound Spring Pair.

Why it ranks #8: Provides two four-leaf double-eye springs rated at 1,750 pounds each for a 3,500-pound trailer axle; detailed dimensions are not provided.

A 1,750-pound rating per spring gives this Magorfas pair a clearly stated 3,500-pound trailer application. Its four-leaf, double-eye configuration and 25-1/4-inch length identify it as a replacement option for buyers matching those specific spring characteristics.

The pair is described as four-leaf, double-eye springs measuring 25-1/4 inches and fitting SW4B applications. Those details help a buyer compare the spring layout and length against an existing suspension before replacement. The stated 1,750-pound capacity per spring supports the listed 3,500-pound trailer use, rather than a higher-capacity setup. The supplied listing does not identify bundled U-bolts or hanger hardware, so plan the replacement around the springs themselves and source any other needed components separately.

Skip it if you need U-bolts or hanger components in the same package; this listing identifies a spring pair, not a hardware kit.

Pick this Magorfas pair when replacing SW4B-style springs on a 3,500-pound trailer and matching the 25-1/4-inch length. It is a spring-focused listing, so buyers needing mounting hardware should plan for that separately.

Listed on Amazon as: Trailer Leaf Spring 4 Leaf Double Eye 1750 lbs Cap for 3500 lbs Axle Suspension 25-1/4" Length fits for SW4B – Set 2

#9

9. SEHNSUCHT 5000-lb Pair

• Weight: 29.3 lb
• Package Dimensions: 28 x 8 x 4.8 in

Best for: Multi-Reference 5000-Pound Springs.

Why it ranks #9: Its four-leaf springs are rated at 2,500 pounds each and list 25-1/4-inch length, 1-3/4-inch width, and several replacement references.

A broad replacement-reference list distinguishes these SEHNSUCHT springs: the listing names SW4, 72-25, UNA218, PR4, 124886, 9150016, and 93181. Each four-leaf spring is rated at 2,500 pounds for a 5,000-pound trailer axle.

The pair measures 25-1/4 inches long and 1-3/4 inches wide, with a 3-inch free opening and 3/8-inch leaf thickness. Eye diameters are listed as 9/16 inch with the bushing and 11/16 inch without it, giving buyers detailed points for comparing an existing spring. The 2,500-pound-per-spring rating supports the stated 5,000-pound axle application. The listing describes springs rather than U-bolt or hanger hardware, so installation components may need separate planning.

Skip it if you need mounting hardware bundled with the springs; this package lists springs, while Aeagle AELS0004Q2 includes U-bolts and hangers.

This SEHNSUCHT pair suits a 5,000-pound trailer owner matching one of its listed replacement references and detailed dimensions. It is a spring-only listing, so plan separately for U-bolts or hangers if needed.

Listed on Amazon as: Trailer Leaf Spring, 4 Leaf 2500lb Double Eye Leaf Springs for 5000lb Trailer Axle, 25-1/4"L, 1.75" Width, 3” Free Open of Leaf Spring, Replace for SW4 / UNA218 / PR4 / 9150016 / 93181, 2 Pieces

#10

10. Magorfas 5000-lb Pair

• Weight: 29.1 lb
• Package Dimensions: 28 x 8.5 x 5 in

Best for: Higher-Capacity 5000-Pound Pair.

Why it ranks #10: This is a 2,500-pound-per-spring option for a 5,000-pound axle, rather than the more common 1,750-pound 3,500-pound-axle setup here.

The 2,500-pound capacity per spring is the defining figure for this Magorfas pair, placing its stated application at 5,000-pound trailers rather than the 3,500-pound class. It uses a four-leaf, double-eye layout and measures 25-1/4 inches long.

For a buyer sorting springs by axle application, the listed 2,500-pound capacity per spring gives a clear starting point for a 5,000-pound trailer setup. The 25-1/4-inch length and four-leaf double-eye design provide additional characteristics to compare with the existing suspension. The listing identifies SW4 fit, while it does not specify bundled U-bolts, hangers, or other mounting hardware. That makes this a spring-focused choice for replacements where the required installation components are already available or sourced separately.

Skip it if you need U-bolts or hangers included; this listing identifies a spring pair, while Aeagle AELS0004Q2 includes an axle hanger kit.

Choose this Magorfas pair for a 5,000-pound trailer owner matching SW4 springs at 25-1/4 inches. The listing focuses on springs, so buyers replacing other suspension hardware will need to address those components separately.

Listed on Amazon as: Trailer Leaf Spring 4 Leaf Double Eye 2500 lbs Cap for 5000 lbs Axle Suspension 25-1/4" Length fits for SW4 – Set 2