SuperSprings SSA39 Rear Helper Spring Kit 3400 lb Fits 2000–2026 Isuzu NPR 4x2

The SuperSprings SSA39 Rear Helper Spring Kit is a patented self-adjusting suspension stabilizing system engineered to improve load handling, eliminate rear-end sag, and reduce body roll on commercial trucks equipped with rear leaf springs. Manufactured in the USA from premium SAE 5160H shot-peened steel, these heavy-duty helper springs automatically adjust as vehicle loads change without requiring air lines, compressors, or maintenance. Designed to work alongside the factory leaf spring pack, the SSA39 provides up to 3,400 pounds of additional load-leveling support while maintaining excellent ride quality. The simple bolt-on installation typically takes about one hour and requires no routine servicing, making it an ideal upgrade for work trucks carrying tools, cargo, equipment, or service bodies.

3400 lb Additional Load Support

Provides up to 3,400 pounds of additional load-leveling capacity to reduce rear-end sag when carrying heavy cargo. The system helps improve vehicle stability without exceeding the manufacturer's Gross Vehicle Weight Rating (GVWR).

Patented Self-Adjusting Suspension

Exclusive roller shackles automatically adjust spring tension as vehicle weight changes. Whether carrying tools, equipment, water tanks, or cargo, the suspension continually adapts without manual adjustment.

Reduces Body Roll & Sway

Designed to reduce body roll by up to 30 percent during cornering and uneven road conditions. The improved stability provides greater driver confidence while maintaining factory ride comfort.

Heavy-Duty SAE 5160H Steel Construction

Manufactured from premium SAE 5160H high-grade spring steel and shot peened to relieve internal stress. This process extends spring life while improving durability under constant heavy-duty use.

Works With Factory Leaf Springs

Designed to operate together with the original equipment leaf spring assembly instead of replacing it. This maintains proper suspension geometry while significantly increasing load support.

Maintenance-Free Operation

Unlike air helper springs, the SSA39 requires no compressors, airlines, valves, or periodic maintenance. Once installed, the system continuously provides dependable suspension support.

Simple Bolt-On Installation

Installs using existing suspension components with adjustable shackles to accommodate various load requirements. Typical installation can be completed in approximately one hour.

Made in the USA

Every SuperSprings helper spring is manufactured in the United States using premium materials and precision engineering. Backed by a Limited Lifetime Warranty and built for demanding commercial applications.

Vehicle Fitment 

Fits the following rear leaf spring commercial truck applications:

Chevrolet: 2000–2009 W3500 Tiltmaster 4x2 • 2000–2010 W4500 Tiltmaster 4x2 • 2000–2010 W5500 Tiltmaster 4x2 • 2004–2009 W5500HD Tiltmaster 4x2

GMC: 2000–2008 W3500 Forward 4x2 • 2000–2010 W4500 Forward 4x2 • 2000–2010 W5500 Forward 4x2 • 2004–2009 W5500HD Forward 4x2

Isuzu: 2000–2026 NPR 4x2

Mitsubishi Fuso: 2005–2011 FE180 4x2 • 2012–2017 Canter FE160 4x2 • 2012–2017 Canter FE180 4x2

Fits vehicles equipped with rear leaf spring suspension only. Never exceed the manufacturer's GVWR.