Auto Service Professional

JUN 2018

Magazine for the auto service professional

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36 A S P J u n e 2 018 C h a s s i s S e r v i c e as opposed to dismantling and replacing the damper, and potentially the coil and the upper bearing. Installing a complete strut assembly has the advantage of everything being new, and sub- stantially reducing shop labor time and offer- ing the customer a faster turnaround. e same concept of offering complete assemblies has now expanded to include complete control arms (that include new bushings and ball joints), complete steering systems, especially on heavier (truck) systems (tie rods, adjuster sleeves, etc.), as well as complete knuckle assemblies that include pre-installed bearings, eliminating the need and time required to press out old bearings and press in new bearings. is increasingly popular trend of using complete assemblies is less labor intensive, ensures a quality repair that requires less time. When a CV joint boot is open (torn, loose, al- lowing contaminants to enter and grease to exit), the joint will soon fail. Warning signs include a clicking sound, especially during slow turns, which indicates a bad outer joint. A rumbling noise/feel is indicative of a failing inner joint. Hydraulic motor mounts (Honda applications are a good example) can wear and begin to expe- rience changes in damping speed, which eventu- ally lead to failure and result in separation. Power rack & pinion steering systems can de- velop a "mystery" leak which may not be visible externally. A slight air leak in the remote fluid reservoir to the pump circuit may cause air to be drawn into the system on the suction side with no signs of external leakage. If air enters the system, it can't bleed itself. We find this most common on Honda and Acura vehicles, but the problem can present itself in any hydraulic power system. In order to diagnose this, place a slight pressure to the reservoir using a radiator pressure tester at 1 psi to 2 psi. While pressured, look for fluid leaks at hoses and connections. Wheel bearing issues sometimes don't ex- hibit looseness and may feel tight, even though the customer may have noted a "strange noise." A handy diagnostic tip is to hold your hand on the coil spring and rotate the wheel by hand. A worn or failing wheel bearing can show itself if you feel a slight resonance/vibration through the spring. Wheel alignment procedures are changing, oen requiring additional steps, thanks to the proliferation of on-board electronics. For exam- ple, on vehicles that feature a steering angle sen- sor, when wheel toe angle is adjusted/changed, on some applications the sensor automatically reca- librates, while on some vehicles a scan tool must be used to command the sensor. Active steering, Worn/deformed control arm bushings allow excessive arm movement resulting in not only noises but erratic changes in toe, camber and caster wheel angles. Note the elongated hole in this steering knuckle's ball joint hole. Improper torqueing of the joint stud may have allowed the stud to wobble inside the bore. PHOTO COURTESY FEDERAL-MOGUL MOTORPARTS PHOTO COURTESY FEDERAL-MOGUL MOTORPARTS

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