A closer look at a planetary gearset shows the location of the planetary pinion thrust washers. Often overlooked during the rebuilding process, few builders closely inspect the planetary gears for wear. Since most planetary gearsets use helical-cut teeth to increase surface area and reduce gear noise, the thrust washers always see some side loading during normal transmission operation. Excessive planetary endplay and worn thrust washers can cause noise and early component failure if they are placed back into service. Always give the planetary gears a close inspection, and rotate them to make sure they are free of any rough spots.