Freightliner 122SD Suspension Parts List: Complete Guide to Components and Replacement

If you own or maintain a Freightliner 122SD, you know the suspension system is critical for load handling, ride comfort, and tire wear. Whether you're replacing worn components or building a stock of spares, having a comprehensive suspension parts list saves downtime. This guide covers every major suspension group on the 122SD, with practical details to help you identify and order the right parts.

Air Suspension Components

The 122SD commonly uses Hendrickson or Freightliner AirLiner rear air suspensions. Air systems provide adjustable ride height and load support.

Air Springs (Air Bags)

Most 122SD rear suspensions use double convoluted air springs. Common part numbers include Hendrickson A-1000 series or Firestone 1T15U-2. Always check the number of air bags per axle (typically two per axle on tandem setups). Replace in pairs to maintain even ride height.

Height Control Valves

These valves regulate air pressure to keep the frame at a preset height. A stuck or leaking valve causes sag or over-inflation. Common brands: Haldex, Hadley. Part examples: Haldex 216511, Hadley 1300 series.

Leveling Valves and Linkage

The mechanical linkage connects the axle to the valve. Rod ends wear out and cause erratic ride height. Replacement kits include new clevises and push rods.

Air Lines and Fittings

Nylon DOT air lines (1/4" or 3/8") and brass push-to-connect fittings. When replacing, use SAE J844 approved tubing.

Leaf Spring Suspension

Front suspension on many 122SD trucks uses parabolic leaf springs. Also used on some heavy-duty rear applications.

Main Spring Packs

Front leaf springs vary based on GVWR. Standard 12,000 lb front axle springs have 3-4 leaves. Part numbers are stamped on the spring. Check Freightliner spring shims for proper camber.

Helper Springs and Overload Springs

Auxiliary springs engage when heavily loaded. Common on heavy-spec trucks. Replace with OEM-spec springs to match load capacity.

Spring Bushings and Pins

Worn bushings cause suspension clunk and poor alignment. Use grade 8 pins and polyurethane or rubber bushings. Typical sizes: 1-1/4" pin diameter, 2" bushing length.

Shock Absorbers

Shocks control oscillation and improve tire contact. The 122SD uses telescopic hydraulic shocks on all axles.

Front Shocks

Usually a heavy-duty monotube design. Common brand Gabriel Fleetline or Monroe Magnum. Part numbers often start with 2400 or 2500 series. Replace in pairs.

Rear Shocks

Mounted at an angle on air suspensions. Key dimension is extended/compressed length. Typical extended length around 25 inches.

Torque Rods and Track Bars

These rods control axle fore-aft movement and lateral location.

Upper and Lower Torque Rods

On Hendrickson suspensions, you'll find two upper and two lower rods per axle. Ends wear and develop play. Replace as a set with new bushings. Common part: Hendrickson 220 series.

Panhard Rod (Track Bar)

On some 122SD with air ride, a lateral track bar centers the axle. A worn track bar causes side-to-side wander. Bushing replacement is typical.

Suspension Bushings and Mounts

Rubber or polyurethane bushings insulate vibration and allow flex.

Spring Bushings

At each leaf spring eye. Worn bushings cause noise and looseness. Replacement requires pressing out old bushing and installing new one with lubricant.

Axle Seat Bushings

Where the axle seats against the spring or air ride beam. Often replace as part of a kit.

Cab Mount Bushings

Not strictly suspension but affect ride. 122SD uses cab isolation mounts. If you feel excessive cab shake, check these.

How to Find the Right Part Number

Every suspension component has a part number stamped or cast into it. Before ordering, clean the area with a wire brush and use a flashlight. If the number is worn, consult the Freightliner parts catalog using your VIN. Many aftermarket brands like Ridewell, Hendrickson, and Raydan offer cross-reference guides. Always compare dimensions—especially length, bushing inner diameter, and bolt pattern.

Practical Replacement Tips

• Always support the frame and axle safely before working under the truck.
• Use OEM or equivalent grade hardware; never reuse suspension fasteners.
• Torque all bolts to factory specs using a torque wrench.
• After replacing air springs or height control valves, recalibrate ride height per Freightliner service manual.
• Replace U-bolts when replacing spring packs; they stretch and weaken.

Final Recommendation

Start by identifying the suspension manufacturer and model (Hendrickson HAS, Freightliner AirLiner, or parabolic spring). Then source a complete kit that includes all bushings, air bags, and shocks for each axle. For most repairs, replacing worn air bags and shocks will dramatically improve ride quality. Keep a spare height control valve and set of air line fittings in your truck for emergencies. Buy from reputable heavy-duty dealers that offer warranty support on suspension parts—avoid no-name brands that lack engineering data. If you're unsure, provide your VIN to a Freightliner dealer for an exact parts list.