This research effort includes hundreds of passenger vehicle wheel alignment measurements and a design of experiments that works to capture the various factors influencing wheel alignment measurements. Of the many things that influence the accuracy and repeatability of vehicle suspension alignment measurement and adjustment, the design of the suspension can be the most significant. This includes but is not limited to adjustment configuration, suspension design, static alignment settings, and bushing stiffness.;Measurements were taken using a Hunter Pro-Align with DSP700 wheel sensors in the Motorsports Research Building at the University of North Carolina at Charlotte. All vehicles were reviewed and any with suspension damage were rejected prior to measurement. The collection of vehicles measured included the category of small front wheel drive, full size rear drive, seven passenger SUV, sports car, and race car. A small sporty sedan was also tested and modified to assess bushing stiffness influence.;Accuracy of the equipment is not a significant part of this study since after a strong attempt to measure it, we were not able to achieve measurements that could sense any reasonable measurement errors. The equipment seems to measure to the 0.01 degree resolution that it claims. Repeatability was evaluated by performing repeated measurements on the same day, a week apart, and over several months. Typically, ten repeats were made during each session and the standard deviation was compared.;The majority of the variability in suspension adjustment and measurement was determined to be from the stiffness (or lack thereof) of the suspension and its bushings. This was found to be the case even for static suspension settings far from the norm. The NASCAR race car with its +6 degree left front (LF) camber had some of the lowest variation in the whole test.
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