When choosing 2 3/8 U-bolts for a trailer axle, the goal is a secure, rust-resistant mounting that fits your leaf springs and frame plates. This guide highlights five top options, explaining who each is best for, and why they stand out. Ideal buyers include trailer owners performing replacement hardware, boat trailer operators, and DIY enthusiasts mounting or repairing suspensions. The tables below summarize key details to compare at a glance.
Buying summary table:
| Product | Axle Type | Length / Thread | Material | |
|---|---|---|---|---|
| SPARKWHIZ Trailer U Bolt Kit (5-1/2″ U Bolts) | 2-3/8″ Round Axle | 5-1/2″ length, 1/2″ diameter, 2″ thread pitch | Best for 3,500 lb trailers needing longer U-bolts | |
| SPARKWHIZ Trailer U Bolt Kit (6-1/4″ Long) | 2-3/8″ Round Axel | 6-1/4″ long, 1/2″ diameter, 3″ thread pitch | Better for longer leaf-spring setups | |
| SVLING 2 Sets Round U Bolts | 2-1/2″ Wide, 2-3/8″ Round Shaft | 2-1/2″W x 3-1/8″L, 3/8″ diameter | Best for corrosion resistance on marine or outdoor use | |
| GREPSPUD 2 Sets Trailer U-Bolts Kit | 2-3/8″ Round Axle | 6-1/4″ long, 1/2″ diameter | Good balance of length and rust protection | |
| MCCKLE Trailer U Bolt Kit | 2-3/8″ Round Axle | 5-1/2″ long, 1/2″ diameter, 2″ thread pitch | Easy install for standard 3,500 lb trailer axles |
SPARKWHIZ Trailer U Bolt Kit, 5-1/2 Inch U Bolts
For 3,500 lb round axles with a 2-3/8″ beam diameter, this kit includes four 5-1/2″ U-bolts, eight nuts, tie plates, and rust-resistant steel construction. Best for longer, heavier-duty trailers needing a robust attach for leaf springs.
- Includes four 5-1/2″ long U-bolts and 8 nuts
- U-bolts diameter 1/2″
- 2″ thread pitch
- Comes with tie plates for 1-3/4″ leaf springs
Best for: Trailer owners who require a durable, long U-bolt set for heavier suspensions. Caution: Ensure axle beam diameter and spring configuration match the kit specifications to avoid fit issues.
SPARKWHIZ Trailer U Bolt Kit for 3,500 lbs. 2 3/8″ Round Axle
This kit is designed for a 3,500 lb trailer with a 2-3/8″ axle diameter. It includes eight U-bolts, 16 nuts, and tie plates for 1-3/4″ leaf springs. Thread pitch is 3″, which can affect compatibility with nut sizes.
- 6-1/4″ long U-bolts overall length option
- 12 total fasteners (nuts and bolts combined)
- Rust-resistant steel construction
Best for: Users needing a longer bolt option for enclosed or heavy-duty trailers. Choose this if your leaf springs require longer engagement. Caution: Verify thread pitch compatibility with existing nuts.
SVLING 2 Sets Round U Bolts (304 Stainless)
Made from 304 stainless steel, these U-bolts are corrosion resistant for outdoors and marine environments. The kit includes 2 U-bolts, frame plates, washers, and nuts. Inner dimensions suit 2-1/2″ width and 3-1/8″ length, with 3/8″ diameter bolts.
- 304 stainless steel for rust resistance
- Includes frame plates, washers, and nuts
- Partial set specifically sized for 2-1/2″ width mounts
Best for: Boat trailers or coastal installations where corrosion resistance is critical. Caution: Check full set dimensions to ensure the 3/8″ bolt diameter matches your current hardware.
GREPSPUD 2Sets Trailer U Bolt Kits
GREPSPUD offers 2 sets of U-bolts with 6-1/4″ length, designed for 3,500 lb trailers with 2-3/8″ axles. The kit includes 8 U-bolts, 16 hex nuts, and compatible washers. The longer length helps with certain leaf-spring configurations.
- 6-1/4″ long U-bolts, 1/2″ diameter
- Includes tie plates for mounting
- Coated to resist rust and corrosion
Best for: Trailer owners needing extra length for dual-plate leaf spring setups. Caution: Confirm the leaf spring size and mounting plate compatibility before purchase.
MCCKLE Trailer U Bolt Kit
Designed for 2-3/8″ round axles on 3,500 lb trailers, MCCKLE provides a 5-1/2″ U-bolt kit with 1/2″ diameter and 2″ thread pitch. Includes necessary tie plates and nuts for a complete mounting package. Construction emphasizes durability and rust resistance.
- 5-1/2″ U-bolts, 1/2″ diameter
- 2″ thread pitch
- Includes tie plates and nuts
Best for: Standard trailer suspensions requiring a straightforward, complete U-bolt kit. Caution: Verify thread pitch and nut compatibility with your existing hardware.
Buying Guide
- What axle diameter and leaf spring size do I have? Confirm your axle beam diameter (2-3/8″) and leaf spring width to ensure correct U-bolt fit and thread engagement.
- Which material suits my environment? Stainless steel offers excellent corrosion resistance for marine or outdoor use, while zinc-plated steel provides a balance of cost and protection for general trailers.
- What length and thread pitch do I need? Longer U-bolts help with certain leaf-spring configurations; thread pitch must match or accommodate the corresponding nuts.
- Are washers and tie plates included? Packages often include frame plates, washers, and nuts—needed for proper load distribution and secure mounting.
- Do I need additional components or a multi-pack? If you’re performing maintenance on multiple axles, a multi-pack can simplify replacements and maintenance scheduling.
FAQ
- What is a 2-3/8 U-bolt used for? It secures leaf springs to trailer axles on many 3,500 lb trailers with 2-3/8″ round axles.
- How do I verify fit before buying? Check axle diameter, leaf spring width, thread pitch, and whether frame plates and washers are included.
- Is stainless steel necessary for outdoor setups? Stainless steel offers superior corrosion resistance, beneficial for boats and coastal trailers.
- Can I mix brands? It’s best to match diameter, length, thread pitch, and load rating; mixing can compromise mounting security.
- What if my leaf springs are a different size? Choose a kit that explicitly lists compatibility with your leaf spring width to ensure a proper fit.
- Do these kits include nuts? Most sets include nuts and washers; confirm contents listed in the product description.