Hellwig 3511 LP-35 3500 lb Helper Spring 2011-2026 Ford F-250/F-350/F-450 SRW

Vehicle Fitment

• 2011-2026 Ford F-250 Super Duty - All Trims, All Cab Styles (Regular Cab, SuperCab, Crew Cab, Cab & Chassis), SRW only, 2WD/4WD
• 2011-2026 Ford F-350 Super Duty - All Trims, All Cab Styles (Regular Cab, SuperCab, Crew Cab, Cab & Chassis), SRW only, 2WD/4WD
• 2017-2026 Ford F-450 Super Duty - Pickup body style, All Trims, All Cab Styles, SRW only, 2WD/4WD
• 2016-2026 Ford F-450 Super Duty - Cab & Chassis configuration, SRW only, 2WD/4WD
• 2016-2025 Ford F-550 Super Duty - Cab & Chassis configuration, SRW only, 2WD/4WD

Fitment Notes

• MOUNTING KIT REQUIRED - SOLD SEPARATELY: The Hellwig 3511 is the spring leaf assembly only. LP Mounting Hardware Kit #25301 must be purchased separately and is required for installation. The 3511 cannot be installed without it.
• SINGLE REAR WHEEL (SRW) APPLICATIONS ONLY - this kit does NOT fit dual rear wheel (DRW / dually) trucks. Confirmed in Hellwig's own product description. DRW Super Duty trucks require a different product.
• FACTORY CONTACT OVERLOAD SPRINGS - CRITICAL NOTE: Do NOT install the 3511 on a vehicle equipped with factory contact overload springs without first removing them. Alternatively, if removing factory overload springs is not desired, use Hellwig Contact Overload Helper Spring Kit #9703 (or applicable year-specific contact overload kit) which is designed to work with - rather than replace - the factory overload spring configuration. Verify your truck's rear spring configuration before ordering.
• F-450 Pickup fitment begins at 2017 (the year Ford introduced the F-450 in retail pickup body style). F-450 Cab & Chassis fitment begins at 2016. Both are confirmed through 2026.
• F-550 Super Duty fitment is confirmed through 2025 per Hellwig's current product page. Verify 2026 F-550 compatibility with Hellwig at 1-800-HELLWIG (435-5944) before ordering.
• For 2008-2010 Ford F-250/F-350 Super Duty, use Hellwig LP-35 part #3518 with mounting kit #25300 - the 3511 is specific to the 2011+ Super Duty platform's spring geometry.
• Compatible with all available Ford Super Duty engine options: 6.2L V8 (2011-2022), 7.3L V8 (2020+), 6.8L V8 (2023+), and 6.7L Power Stroke Diesel (2011+) across all applicable years.
• Compatible with all cab styles and bed lengths - cab and bed configuration do not affect rear leaf spring helper fitment.

Features

• Up to 3,500 lb. level load carrying capacity - the highest-rated steel leaf helper spring in Hellwig's lineup for the 2011+ Ford Super Duty, delivering 40% more supplemental load support than the LP-25 (part #2511) for the most demanding fleet, commercial, and heavy fifth-wheel or gooseneck towing applications.
• Progressive rate (Fulltime Spring Rate) design - provides a consistent, firm support response that activates progressively as the factory leaf pack compresses under load. Designed for vehicles that carry heavy loads on a regular or continuous basis.
• 4-leaf multi-leaf stack construction spans both sides of the rear axle, delivering maximum bilateral support, superior resistance to body roll and trailer sway, and consistent side-to-side leveling control under the most demanding sustained payloads.
• Fully adjustable load rate - the LP-35 mounting hardware provides independent left/right U-bolt adjustment for fine-tuning load distribution and correcting uneven side loads from upfitter bodies, truck camper placement, or off-center commercial cargo.
• Each spring leaf is hot-formed and heat-treated from ASTM 5160 alloy spring steel for maximum strength, fatigue resistance, and long-term durability under continuous heavy-duty use.
• Silver hammertone powder coat finish provides corrosion resistance and a professional appearance on underbody hardware exposed to road salt, diesel exhaust, and wet-weather conditions.
• Eliminates the rear-end sag, squat, and body roll that degrades headlight aim, front-axle traction, steering response, and brake performance when Super Duty trucks are loaded at or near their GVWR.
• Reduces leaf spring wrap-up and axle hop under hard acceleration with heavy payloads - especially beneficial for high-torque Power Stroke diesel applications pulling fifth-wheel trailers or operating commercial upfitted bodies.
• "Set it and forget it" design - once installed and adjusted, the LP-35 requires zero ongoing maintenance. No air bags, compressors, sensors, or electronics to service, fail, or leak in the field.
• Bolt-on installation using common hand tools - no drilling, cutting, or permanent modifications required to any factory suspension component.
• Manufactured at Hellwig's ISO 9001 and ISO 14001 certified facility in Visalia, California - made in the USA since 1946, backed by Hellwig's Limited Lifetime Warranty against manufacturing defects.

Specifications

• Level Load Capacity: Up to 3,500 lbs.
• Spring Series: LP-35 (Load Pro 35)
• Spring Rate Design: Progressive Rate / Fulltime Spring Rate
• Construction: 4-leaf multi-leaf stack
• Spring Material: ASTM 5160 heat-treated alloy spring steel
• Spring Finish: Silver hammertone powder coat
• Drivetrain Compatibility: Single Rear Wheel (SRW) ONLY - does NOT fit DRW/dually
• Leaf Spring Type Compatibility: Multi-leaf rear spring packs only
• Mounting Kit: Required - sold separately (Mounting Hardware Kit #25301)
• Drilling Required: No
• Country of Manufacture: USA (Visalia, CA - ISO 9001 / ISO 14001 certified)
• Warranty: Limited Lifetime
• Quantity: Sold as a kit (spring leaves only - mounting hardware sold separately)

Included Components

• 2x LP-35 4-leaf spring assemblies (1 per side), ASTM 5160 alloy steel, silver hammertone powder coated
• Installation instructions
• Note: LP Mounting Hardware Kit #25301 is NOT included and must be purchased separately for installation.

Product Description

The Hellwig 3511 LP-35 Heavy Duty Load Leveling Helper Springs deliver the highest level of steel leaf spring supplemental load support available in Hellwig's catalog for the 2011-2026 Ford Super Duty - 3,500 lbs. of progressive load capacity, 40% more than the LP-25 (part #2511). Purpose-built for the most demanding 3/4-ton and 1-ton SRW Super Duty applications, the 3511 is engineered for fleet operators, commercial upfitters, heavy fifth-wheel and gooseneck towers, and truck camper owners who consistently push their F-250, F-350, or F-450 to or near the vehicle's rated GVWR. The progressive Fulltime Spring Rate design delivers immediate, progressive support as the factory leaf pack compresses - providing continuous load control rather than waiting for a load threshold to be reached, making it the superior choice over the LP-25 for trucks that carry heavy loads day in and day out.

The 3511 uses a 4-leaf multi-leaf stack that spans both sides of the rear axle, providing maximum bilateral load distribution and superior resistance to body roll and trailer sway under extreme sustained loads. The required LP Mounting Hardware Kit #25301 (sold separately) supplies the vehicle-specific U-bolts and axle brackets for installation without drilling, and provides independent left/right load adjustment for correcting uneven loads from upfitter body weight, camper mounting position, or asymmetric cargo. Each spring leaf is hot-formed and heat-treated from ASTM 5160 alloy spring steel and finished in silver hammertone powder coat. Once installed, the LP-35 requires zero maintenance - no air bags, compressors, sensors, or electronics to service in the field.

The 3511 is confirmed for F-250/F-350 through 2026, F-450 pickup through 2026 (with pickup body fitment beginning 2017; Cab & Chassis from 2016), and F-550 Cab & Chassis through 2025. This kit is SRW only - DRW trucks require a different product. Factory contact overload springs must be removed before installation, or Hellwig Contact Overload Helper Spring Kit #9703 must be used instead if the factory overloads are to be retained. For 2008-2010 F-250/F-350, see Hellwig part #3518 with mounting kit #25300. Manufactured at Hellwig's ISO 9001 and ISO 14001 certified factory in Visalia, California and backed by a Limited Lifetime Warranty.