Frequently Asked Questions About Freightliner SD 108-122 Steering Parts & Accessories

What years and models are compatible with SD 108-122 steering components?

The SD (Severe Duty) 108-122 designation covers Freightliner trucks from model years 2002-2017, including the FLD112, FLD120, Classic, Classic XL, Columbia, Coronado, and Century Class models. These parts are specifically engineered for severe duty applications with GVWRs ranging from 108,000 to 122,000 pounds. Always verify your truck's specific model designation on the door jamb sticker before ordering, as some transitional year models may have different specifications.

How difficult is it to install steering gearboxes and components on these models?

Installing major steering components like gearboxes typically requires 4-6 hours for experienced mechanics and specialized tools including a pitman arm puller, torque wrench capable of 450-500 ft-lbs, and proper alignment equipment. The most challenging aspects include removing the old pitman arm (often seized), properly setting sector shaft end play, and ensuring correct steering wheel centering. We strongly recommend professional installation for gearboxes, while simpler components like drag links and tie rod ends can be DIY projects with basic heavy-duty tools.

What's the difference between TRW and Sheppard steering gearboxes for my truck?

TRW Ross (now TRW Commercial Steering) and Sheppard are the two primary OEM suppliers for these models. TRW units typically have a 23:1 or 20:1 ratio and are identified by casting numbers starting with "TAS" or "THP." Sheppard boxes usually feature 16:1 or 18:1 ratios with "M100" or "M110" designations. While both are quality units, they have different mounting patterns, input shaft splines, and hydraulic connections. Check your existing gearbox identification tag before ordering - mixing brands requires extensive modifications and isn't recommended.

Are aftermarket steering shafts and u-joints as reliable as OEM parts?

Quality aftermarket steering shafts from reputable manufacturers like Borgeson, Sweet Manufacturing, and Flaming River often exceed OEM specifications. Look for shafts with needle bearing u-joints rather than plastic bushings, DD (Double-D) connections that match your gearbox input, and proper collapse ratings for safety. Avoid economy imports that use inferior steel or lack proper spline engagement depth. Premium aftermarket options typically feature improved materials like 4130 chromoly steel and sealed u-joints that outlast factory components.

What are the warning signs that my steering stabilizer needs replacement?

Replace your steering stabilizer if you experience wandering at highway speeds, excessive steering wheel vibration over bumps, or visible oil leaking from the shock body. On SD 108-122 models, worn stabilizers often manifest as "death wobble" between 45-55 mph, especially with worn tires. A simple test involves disconnecting one end and manually compressing the stabilizer - it should provide firm, consistent resistance in both directions without dead spots. Most heavy-duty applications benefit from dual stabilizer setups, and replacement intervals typically range from 100,000-150,000 miles depending on road conditions.