Bearings are what allow the gears to rotate smoothly. They are generally manufactured from bronze or brass, plus they suit into races (or grooves) inside the gearbox housing. Really hard shifting, minimized fuel performance, and burning smells are just several of the signs and symptoms of a nasty transmission filter. https://elliottufmsw.ltfblog.com/33042424/the-single-best-strategy-to-use-for-filter-gearbox