Truckers News

May 2011

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BIG RIG BASICS JOHN BAXTER Spring Time Avoid expensive repairs through regular suspension maintenance pring suspensions are used on most front axles and are popu- lar on the tandems of on/off-road vehicles because they are less easily damaged. Regular inspection and greasing of this system will head off expensive repairs, help reduce tire wear and improve handling. S 1 2 3 Look at the shock absorber mounts and the bushings inside. Torque shock mounting bolts to specification. Replace the bushings, or have them replaced, if cracked or loose. Feel the shock absorbers after the truck has been driven two miles or more. Replace any not warm to the touch. Replace every 100,000 miles to guaran- tee good performance. Shocks in good working order will preserve springs, bushings and other parts, along with ride. Inspect the areas around the spring U-bolts for a fine layer of rust due to chipped paint. Tap 2 PRODUCT TIP Technician Brad Galla recommended using gas-filled shocks rather than conventional designs. The fluid in normal shocks can get air in it during hard running, which causes performance to deteriorate. The nitrogen used in gas shocks won’t dissolve in the fluid and cause it to thin out, ensuring much more consistent performance. 30 TRUCKERS NEWS MAY 2011 on them with a hammer. A solid sound means they are tight, while a rattle or ringing noise means looseness. If loose, look up factory specifications and torque with a torque wrench. If the bolts fail to torque prop- erly, have them replaced and prop- erly torqued. If very loose, the cen- tering pin for the spring may be worn or its locating hole enlarged. Have the alignment reset. Torquing these every 100,000 miles will minimize the need for repairs. 4 Check the springpins at the ends of springs by listening for a snapping noise or seeing loose- ness at the end of the spring as a helper rapidly turns the steer- ing wheel back and forth. You’ll see the motion inside the rubber 4 SUSPENSION MAINTENANCE Time needed: 90 minutes Tools needed: Level of difficulty (scale 1-5 with 5 being the hardest job): 2 1. A floor jack of sufficient rating. 2. A torque wrench of appropriate rating. 4. Factory literature listing torque specifications, greasing intervals, etc. bushing that fits inside the spring. You can also check by look- ing for up-and-down play inside the bushings when the truck is raised on a floor jack. Replace worn spring- pins. Regular greasing with the truck sitting normally or off the wheels, depending on manufacturer recom- mendation, will pre- vent wear. 3. A helper to operate the steering system while you observe the suspension. 5 Check the spring- pin rubber bush- ings for wear. Bush- ings not tight in the ends of the springs, or springs off cen- ter in their hang- ers, are signs of wear here, and the sides of the springs, and the insides of their eyes, can wear, too. You can also check for play here by having someone turn the steering wheel back and forth as you watch the front suspen- sion. Replace worn bushings or 1

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