The initial test drive is important to verify the symptom(s) the vehicle owner has described, and where you may also recognize problems or symptoms they have not described or do not recognize. As a precursor to the test drive, walk around the vehicle and perform a visual inspection. Look closely at suspect areas identified by the customer.
Did they hit a pothole or hear a noise from a particular area? Look for wheel or tire damage, body damage, or loose fender liners or underbody panels that can clue you in to possible damage, which may be the cause of a noise.
During the test drive, be sure to duplicate the driving conditions described by the customer as closely as possible, obeying the posted speed limits and laws. Follow a pre-determined test-drive route to encounter various road conditions from smooth to rough and requiring regular acceleration, deceleration and turns. Depending on the symptom, it may be necessary to drive the vehicle at freeway speeds.
Pay attention to any noises or vibrations, when they occur, and the speeds and the conditions under which they occur. Make sharp turns in a parking lot and follow a curvy road, when possible, to identify difficult or unstable steering, and look for evidence of alignment issues such as a drift or pull.
Remember, in addition to diagnosing a specific problem, you are performing a professional assessment of the vehicle steering and suspension. A vehicle owner may not always accurately describe a symptom or accurately report any damage or vehicle abuse, and when this is the case, it is almost always inadvertent.
They may have loaned their car to someone who didn’t report any damage, or something may have occurred that they simply forgot about. Either way, it’s important to be thorough and provide them with an objective report on their vehicle condition.
After the test drive, begin your inspection by performing a “bounce test” with the vehicle on the ground. This is the first step in your comprehensive corner check,” to ensure ultimate vehicle safety and reliability. Push down sharply at each corner of the vehicle and focus on a fixed point as the suspension rebounds. The vehicle should return to ride height with no additional movement.
If the vehicle bounces at all, it indicates the shock absorbers are worn and no longer able to properly dampen the movement of the suspension springs. You may see results ranging from perfect operation to very mild signs of wear, to excessive wear and unsafe driving conditions. To develop this skill, perform this test even on new vehicles. The more you do, the more familiar you will become with the subtle signs that indicate a shock absorber is wearing out.
Depending on vehicle age, mileage and symptoms, you may choose to measure ride height prior to lifting the vehicle. Service information will list the specification and where to measure it, and when it’s out of spec, it’s a clue to look for a broken spring or other damage to the suspension.
Lift the vehicle off the ground until the wheels are at a normal working height and perform a visual inspection of shocks, struts and springs, looking for signs of leakage, broken springs or damaged dust boots or bump stops. Check tire pressure, then grab each wheel at the 12 and 6 o’clock position, and attempt to rock it back and forth to check for play. Do this again at the 3 and 9 o’clock position.
Fully raise the vehicle and closely inspect the components at each corner. Spin the wheels to look for a bent or damage wheel and look closely at the tire tread around the complete circumference. Measure and record the tread depth and use your hand to check for inconsistencies in tread wear, such as feathered edges that may indicate an alignment problem.
Look for torn or leaking CV, tie rod, ball joint or steering rack boots, and look for any oily type of residue around suspension bushings that may indicate a worn hydraulic suspension bushing. With a visual inspection complete at each corner, now it’s time for a mechanical inspection. If you noticed any free play during your initial “shakedown” of the wheels, you’ll want to focus on determining the cause, but keep in mind that different steering and suspension designs call for different methods of inspection.
Utilize manufacturer-specific information to ensure you are using the proper methods to check ball joints and tie rod ends for wear. In some cases, a certain amount of wear is acceptable, but even more critical is the type of suspension and location of the ball joints. Loaded ball joints are those that support the weight of the vehicle and can be identified by the location of the coil spring.
Follower ball joints do not support the weight of the vehicle, but are critical to maintaining alignment angles during steering and suspension movement. What’s important about this as you perform the mechanical portion of your inspection is that without using the proper method of inspection, you can miss a bad component.
Loaded ball joints must be unloaded in order to check them for wear, and this is accomplished by utilizing the proper jacking point under the frame or suspension. In many cases, a follower ball joint can be easily checked when the suspension is hanging, but depending on the type of suspension, this may also create a tension or compression load on the joint. So, if you are unsure of the proper method, be sure to reference manufacturer procedures.
You will also need to use a prybar in many situations to identify the play in a ball joint or suspension bushings, and a dial indicator is often required to determine if any play is within acceptable limits. Don’t take shortcuts when it comes to the inspection process. There are no shortcuts that work. Take the time and follow manufacturer procedures to ensure a thorough and accurate inspection.
As you finish up your mechanical inspection, be sure to inspect sway bar links and bushings, steering shafts for play or binding, and inspect strut tops or turn bearings for smooth operation and excessive wear.
It’s safe to say in most cases, an alignment is necessary only after repairs have been completed. However, when you’re diagnosing a specific steering or handling problem and you don’t identify any loose or worn components, checking the alignment is a way you can identify bent components, and this may be necessary as part of the diagnosis. Once you’ve completed a thorough corner check of the system, you’re ready to perform the repair.
Coming up in Part 5 of this series, is a comprehensive review of seasoned repair techniques to efficiently perform a quality repair.
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