Peterbilt 375/377 Steer Axle Springs & Hangers

Frequently Asked Questions About Peterbilt 375/377 Steer Axle Springs & Hangers

What is the difference between steer axle springs and hangers, and why do I need both?

Steer axle springs are the leaf springs that support the front axle and absorb road shock, while hangers are the mounting brackets that attach those springs to the truck frame. Both work together as a system, so when one component wears out, the other is often close behind. Replacing them as a set helps ensure proper fit and even load distribution across the front suspension.

How do I know if my springs or hangers need to be replaced?

Common signs include uneven tire wear, a truck that pulls to one side, sagging on one corner of the front end, cracked or broken leaves, and visible rust or metal fatigue around the hanger mounts. Unusual clunking or squeaking noises over bumps can also point to worn bushings or loose hanger hardware. If you notice any of these symptoms, it is worth having the front suspension inspected before they lead to steering or alignment issues.

Will these springs and hangers fit both the 375 and 377 models without modification?

Parts listed in this category are designed to fit the Peterbilt 375 and 377 steer axle applications, but exact fitment can still depend on your truck's specific build date, axle configuration, and original equipment setup. We recommend checking part numbers against your truck's VIN or existing components, or reaching out to our parts team to confirm compatibility before ordering.

What materials and finishes are these springs and hangers made from?

Steer axle springs are typically made from heat-treated alloy steel to handle the constant flexing and load-bearing demands of the front axle, while hangers are usually cast or forged steel for strength and durability. Finishes vary by manufacturer, with many parts featuring a protective coating or paint to help resist corrosion from road exposure, salt, and moisture.

Can I install steer axle springs and hangers myself, or should I have a professional do it?

Replacing steer axle springs and hangers involves working with heavy components under load and often requires proper lifting equipment, torque specifications, and alignment checks afterward. While an experienced diesel technician with the right tools can handle the job, this is generally not a recommended DIY task for most owner-operators due to the safety risks and the need for accurate front-end alignment once the new parts are installed.