Peterbilt 379 Leaf Springs, Hangers & Acc.

Frequently Asked Questions About Peterbilt 379 Leaf Springs, Hangers & Acc.

Will these leaf springs fit my specific year Peterbilt 379, and what are the weight capacity differences?

Our leaf springs are designed to fit Peterbilt 379 models from 1987-2007. However, weight capacities vary based on your truck's configuration. Standard 3-leaf springs typically handle 12,000-14,000 lbs per axle, while heavy-duty 4-leaf options support 16,000-20,000 lbs. Always verify your truck's GAWR (Gross Axle Weight Rating) on the door jamb sticker before ordering. Extended hood models may require different spring eye dimensions, so measure your existing spring eye-to-eye distance or contact us with your VIN for verification.

What tools and equipment do I need to replace leaf springs and hangers myself?

You'll need a heavy-duty floor jack (minimum 20-ton capacity), jack stands rated for commercial trucks, a 3/4" drive socket set, penetrating oil, and a torque wrench capable of 450-500 ft-lbs. Spring compressors are highly recommended for safety. The job typically takes 4-6 hours per side. Critical torque specs: U-bolt nuts require 300-350 ft-lbs, and hanger bolts need 450-500 ft-lbs. Many customers report seized pins and bushings on trucks over 10 years old, so budget extra time for removal.

What's the difference between OEM-style and aftermarket leaf springs, and which should I choose?

OEM-style springs use the same steel specifications and arch measurements as factory Peterbilt springs, maintaining original ride height and characteristics. Aftermarket options often feature upgraded steel alloys and may offer 1-2 inches of lift. OEM-style is best for maintaining factory ride quality and alignment specs. Aftermarket heavy-duty springs work well for vocational trucks or those regularly hauling near maximum capacity. Both options in our inventory meet or exceed DOT standards.

How do I know when my leaf spring hangers and shackles need replacement?

Inspect hangers for cracks around bolt holes, excessive rust penetration (more than surface rust), or elongated mounting holes. Shackles should pivot freely without binding or excessive play. Warning signs include uneven tire wear, truck leaning to one side, clunking noises over bumps, or visible gaps between spring leaves. Hangers typically last 15-20 years in normal conditions but may need replacement sooner in salt belt states. Always replace hangers in pairs to maintain proper alignment.

Can I mix different brands of leaf springs and hangers, or should I stick with matched sets?

While different brands can technically work together if dimensions match, we recommend matched sets for optimal performance. Mixing brands may result in slight ride height variations or uneven weight distribution. Critical measurements to match include spring width (typically 3" or 3.5"), eye diameter (usually 1.5" or 1.75"), and center bolt pattern. Our Dayton, Hendrickson, and Reyco components are engineered to work interchangeably within the same specification range, but always verify measurements before mixing components.