<div class="htmlview paragraph">Results of a psychophysical experiment indicated that “jerk” (that is, rate of change of fore and aft acceleration) associated with the clutch-actuated gear ratio change in an automatic transmission correlated well with subjective evaluations of shift-feel. A portable device, the GMR Jerkmeter, was constructed to measure acceleration and jerk during on-the-road evaluations of transmission performance.</div> <div class="htmlview paragraph">Techniques for using Jerkmeter data in automatic transmission fluid research and development projects are discussed. Examples are given of the use of Jerkmeter data to: <ol class="list nostyle"> <li class="list-item"> <span class="li-label">1.</span> <div class="htmlview paragraph">Produce a detailed characterization of shift performance.</div></li> <li class="list-item"> <span class="li-label">2.</span> <div class="htmlview paragraph">Measure effect of fluid on shift performance.</div></li> <li class="list-item"> <span class="li-label">3.</span> <div class="htmlview paragraph">Study effect of changes in fluid characteristics with use.</div></li></ol></div>