Siapupy Trailer Leaf Spring Kit 3.5K–7.2K Axles — Heavy-duty Corrosion-Resistant Shackle & Equalizer Set

Siapupy Heavy-Duty Trailer Shackle Leaf Spring Kit is a complete, corrosion-resistant replacement set engineered to restore tandem-axle trailer suspension performance for 3,500–7,200 lb axles.

This comprehensive kit supplies the core hardware and components you need to repair or replace double-eye leaf spring suspensions on utility, boat, and cargo trailers. Built from steel with an anti-rust finish, the parts are designed for routine road use and saltwater exposure. The package includes equalizers, shackle straps, bushings, bolts, and locking nuts sized to fit common trailer hanger and spring configurations, so you can complete a dependable repair in a home garage or professional shop.

How does this kit fit my trailer's suspension?

The Siapupy kit is matched to double-eye, tandem-axle setups rated between 3,500 and 7,200 pounds per axle. Key measurements are designed to align with standard trailer spring hangers and equalizer positions.

• Equalizer hole spacing: 7-3/4"
• Shackle strap length: 4.38" with 3-1/8" (3.12") hole spacing
• Bushing I.D.: 9/16"; O.D.: 11/16"
• Bolt length: 3-3/8" with 9/16"-18 thread; locking nuts included

What parts are included and why each matters?

This set bundles the critical suspension pieces so you don’t need to source multiple components separately. Each item supports proper alignment, load transfer, and wear resistance in a trailer suspension system.

• 2 long triangular equalizers — balance spring loads between axles
• 8 shackle straps — connect springs to hangers while allowing movement
• 8 nylon leaf spring bushings — reduce metal-on-metal wear and noise
• 14 shackle bolts and 14 locking nuts — secure fasteners that resist loosening

How durable and corrosion-resistant are these components?

Siapupy uses steel construction with an anti-rust coating to extend service life under road and marine-adjacent conditions. The finish and materials focus on reducing common wear points and maintaining fit over time.

• Steel parts for strength under regular towing loads
• Protective anti-rust coating to resist salt and moisture exposure
• Locking nuts engineered to hold torque under vibration
• Nylon bushings to limit abrasion and isolate shock

How easy is installation for DIYers and mechanics?

The kit is supplied as a ready set of matched parts, simplifying part selection and reducing trips to the hardware store. Basic tools for trailer suspension work and routine shop procedures are all that’s required for installation or replacement.

• All necessary fasteners and bushings included in one box
• Fits standard trailer hangers and double-eye springs without modification in most cases
• Can be installed in a home garage or professional workshop
• Locking nuts help avoid re-torquing under normal conditions

Who is this for? The Siapupy Heavy-Duty Trailer Shackle Leaf Spring Kit is ideal for trailer owners, fleet maintainers, and repair shops that need a reliable, ready-to-install suspension parts package for tandem-axle utility, boat, or cargo trailers in the 3,500–7,200 lb range. Whether you’re replacing worn shackles and bushings after years of service or rebuilding a suspension during restoration, this kit groups the correct sizes and corrosion-resistant components to finish the job efficiently.