Auto Service Professional

JUN 2018

Magazine for the auto service professional

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Page 49 of 69

48 A S P J u n e 2 018 C h a s s i s S e r v i c e idler arms, pitman arm or idler arm mountings are all suspects when inspecting for a wandering complaint. Wheel bearings Check the condition of the wheel bearings. Loose or worn wheel bearings will result in excessive lateral wheel play, easily contributing to a some- times twitchy wander issue. Moisture contamination is one of the primary causes of roller or ball bearing failure. Moisture leads to bearing overheating, deterioration of bearing grease and corrosion and bearing noise. A drone or whirring noise can oen be misdiag- nosed as a wheel bearing issue, where uneven tire tread wear may be the actual cause. Noises tend to travel and may be generated by a wide range of chassis components, sometimes making pin- point diagnosis difficult. Chassis ears Chassis ears, a somewhat generic term for equip- ment that allows you to monitor noise and vi- bration, can be extremely useful for pinpointing issues with a wide variety of components. Cur- rently available chassis ears offer ease of use and outstanding diagnostic capabilities. An example is Steelman's Wireless ChassisEAR. e control unit/receiver is wireless, powered by AA batter- ies. e kit includes four vibration/noise trans- mitters, each powered by AAA batteries. Simply attach the transmitter(s) to the area or compo- nent you wish to test. Attachment methods vary, depending on the mounting surface. e transmitters feature two internal mag- nets that allow a secure mount to an appropri- ate surface, although the magnets don't appear strong enough to hold well on rusty or greasy surfaces. If the surface mount area won't pro- vide a reliable hold, provided Velcro straps can be used to secure the unit, which provide a very secure grip. Each transmitter also features a strong spring clip, so depending on the mount- ing surface, you have three mounting options. Each transmitter accepts a plug-in cable that features a spring clamp. Attach the clamp close to the area/component that you wish to monitor. Each transmitter is boldly identified with a number (1, 2, 3, 4), with corresponding illumi- nated push buttons on the receiver. While the receiver features transmitter-related buttons and a row of noise-intensity LED lights that provide a good visual signal, it's best to also plug in the supplied earphones that allow you to hear noises. Take the vehicle for a test drive, and press the button (channel) desired and lis- ten for noises. is makes it easy to compare, for example, le and right wheel bearing noises on the same axle. If the channel 1 transmitter is listening to the le front wheel bearing and the channel 2 transmitter is monitoring the right front wheel bearing, you can compare the two noise sig- nals, listening for evidence of abnormal grind- ing sounds, etc. For example, if you suspect a wheel bearing problem, in addition to monitoring both front wheel bearings, you can attach a third trans- mitter to the transmission and a fourth to the differential. Noises and vibrations tend to trav- el, and since the unaided human ear might sus- pect a wheel bearing, the noise may actually be coming from another source such as the trans- mission. Using this type of monitoring system Moisture migration is a leading cause of wheel bearing failure, as lubrication decreases and rust forms.

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