Bearings are what enable the gears to rotate smoothly. They are usually made out of bronze or brass, and so they fit into races (or grooves) while in the gearbox housing. Challenging shifting, reduced gas performance, and burning smells are just a number of the symptoms of a nasty transmission https://filter-gearbox79886.bloguetechno.com/filter-gearbox-can-be-fun-for-anyone-69197058