Tools Used:
- Scanner
- Service Information System
- Tire Tread Depth Gauge
- TPMS Tool
- Portable Audio Recorder
- NVH Kit (optional but recommended)
- Alignment System
Vehicles have never been more interdependent than they are these days. A small hiccup in one system can have a domino effect on others, leading to a multitude of issues that can give even an experienced technician pause. Even routine jobs have become increasingly more complex, making the need for sound and consistent processes increasingly important. This holds true whether we are diagnosing a drivability complaint or an alignment issue. The more data we can reference, gather, and analyze quickly and efficiently, the more likely we are to have successful first-time resolution for our customers, regardless of the concern.
There are a variety of situations in which an alignment and/or wheel service may be performed. The customer may simply request an alignment, at which point our jobs as data gatherers begins. There are a few questions to ask at this point, such as: Why do you want an alignment? What symptoms are you experiencing and under what conditions are you experiencing them? Have you recently had any collision damage? The answers to these questions can help us gather the information we need to address customer concerns.
Customers often bring vehicles in after experiencing common symptoms like pulling, drifting, bump-steer or wandering, vibrations, a crooked steering wheel, noises while turning, or uneven tire wear. The same questions asked before still apply in this situation. Our first interaction with the customer is critical to the information gathering stage that will be the building block of a proper complaint, cause, and correction sequence.
Developing and following an organized process is the first step to success. This process is one I have in place for any customer with an alignment, noise, vibration, harshness (NVH), or wheel complaint.
Step 1: Full system scan and courtesy check
Regardless of what a vehicle has come in for, each receives a full system code scan and a courtesy check. Given the increasing prevalence of advanced driver assistance systems (ADAS), generating a comprehensive picture of the vehicle’s health has never been more important. Alignment angles are a direct value upon which electronic power steering, stability control, and lane keep assist systems are built. Just as alignment values out of specification can negatively impact these systems, the inverse can happen as well.
The system scan and courtesy check are performed concurrently. As the scanner is performing the health report (Figure 1), we should be checking tire and wheel condition visually and confirm tire pressures utilizing TPMS data within the vehicle information center or scan data (Figure 2). Now’s the time to note any mismatched wheel/tire sizes as well as any damage or modifications to the vehicle.
These vehicle modifications, such as different wheels/tires, brush-guards or aftermarket grills, the presence of “go-fast goodies,” or modified suspension all have their own impacts upon the base vehicle operating characteristics. This is especially true with suspension modification, as this leads to modified suspension geometry (lowered, lifted, stiffer) and may compound faults already present.
While these changes may not be the root cause of our faults, it’s always important to observe, notate, and keep them in the back our minds during the next step of our process.
Step 2: Test drive
A test drive should be performed on every vehicle to confirm not only the customer’s complaint, but also to evaluate any other concerns that may be present. During the test, be sure to drive the vehicle exactly as the customer drives it (or as closely as possible). Note any pulls, drifts, bump steer, torque steer, clunking, banging, or vibrations as well as when they occur.
I have a small pocket audio recorder that I place in the cup holder to record my test drive. However, most cell phones have some kind of audio recording app that’s more than sufficient for test drive purposes. This recording not only allows me to capture certain noises, but also gives me a quick and easy method of narrating my test drive and notating changes in vehicle feel based on current driving conditions.
Having a consistent test drive loop that covers multiple road textures, speeds, and conditions is paramount to identifying and remedying complaints. Identifying a repeatable acceleration style, braking style, and monitoring customer test drive and conditions allows us to more quickly pinpoint if we are dealing with an alignment, wheel balance, drivetrain, engine fault or just natural characteristics of a given vehicle under certain driving conditions.
Be sure to document and differentiate between cabin, suspension, engine noises/vibrations, and tire noises. Pay attention to any symptoms that may change, either disappear or get worse, during the test drive. Tires are just one example of a symptom that may come and go. As tires warm up, their characteristics may change and lead to a change in the complaint’s severity.
Another important factor in our process is understanding that different people have different levels of sensitivity to faults. When in doubt, we should always consult with the customer to discern their priorities and that we are in fact experiencing the same symptoms that they are.
Step 2A: Test drive with NVH tooling
Using some type of NVH tooling (Figure 3) allows technicians to gather more data during a test drive and help to pinpoint issues even more clearly. The potential usage cases are near endless. Multiple OEMs are including NVH testing into their diagnostic routines to help isolate failures of everything from misaligned mounts to torque convertor shudder and more.
NVH data can quickly allow technicians to differentiate between a wheel/tire vibration, suspension or mount fault, an out-of-balance driveshaft, or engine harmonics. This data takes us further from subjective analysis and puts the symptoms into a format that is much more objective, as well as being useful in the future as a record of a “known good” or “known bad” vehicle. This creates the ability for a technician to back up their “gut feeling” of shifted cords in a tire or a failing wheel bearing with concrete readings from previous failures on the same or similar vehicles. The more data we have, the more we can feel confident in performing the proper repairs for the customer.
The ability to document before and after vibration measurements is just another arrow in the target of a first-time fix. These reports add another level of value to the alignment and balancing services that technicians are currently providing. There are a few systems out there, so research is key to making a selection.
Step 3: Initial alignment check out
Now we are ready to hit the alignment rack and get our measurements (Figure 4). Proper installation of the alignment heads (per the system’s instructions) is a critical first step here.
Once we've gathered our initial readings, it's time to take a second to examine and analyze the data and see where it is pointing us.
First off, there are the regular angles we are all familiar with: camber, caster, toe, and thrust angle. Thrust angle has become even more important in recent years due to the advent of ADAS and many OEMs dictating that calibration target set-up and measurements are based off of the center line of the vehicle. Without a proper thrust angle, every other angle and related system will not function optimally.
Steering axis inclination (SAI) and included angle are two additional angles, often called diagnostic angles, that are incredibly important when it comes to analyzing and performing alignments.
SAI is a very important and often overlooked component of alignment diagnostics. SAI causes both front wheels to gain positive camber as they steer away from the center line. When combined with the proper specification caster angles, the front wheels self-center and help generate straight line stability.
As the wheels turn to one side or the other, the wheel is pushed up, which raises the front of the vehicle. The weight of the vehicle is also pushing down on the suspension so that when the steering wheel is released the wheels, and steering wheel, return to center.
A zero-degree SAI measurement would lead to no self-centering; if the angle is too large, generally above eight degrees, the front axle tends to raise when steering. When combined with bumpy roads, bump steer is experienced. Steering becomes very hard to control and straight-line stability suffers.
When SAI and camber measurements are combined, we gain our included angle (IA) measurement. These three bits of data can be used to determine the presence and location of bent or damaged components before we attempt to adjust any angles. There are various charts available that help determine the likely location of the damage based off the alignment measurements and suspension design.
While often overlooked, these diagnostic angles allow us to make an accurate determination as to where faults are located and when combined with all our other data, we can generate the best repair plan for a customer that doesn’t leave us with any surprises once the job has been completed.
Step 4: Data analysis
We’ve now collected all the information we need to make an informed decision on how to correct the customer’s complaint. Through a combination of data garnered from the customer interview, road test observations (with or without NVH readings), and alignment readings, we can best determine the most effective course of action to remedy the existing complaints as well as possibly alerting the customer to impending suspension issues or failures down the road.
Once the best course of action has been determined, parts can be ordered (if needed) and repairs, adjustments, and a verification road test can be performed.
Data is a modern-day technician’s best friend. Vehicle systems can no longer be truly isolated and evaluated as free-standing systems. We must evaluate the vehicle as a whole and use various tools and techniques to gather the most information possible. Following best practices, a sound and repeatable process, and good data analysis will allow us to diagnose and remedy any complaint our customers may bring forward.
