Automatic Transmission Bearings
There are several different types of bearings found in an automatic transmission. Each bearing and washer serves a unique purpose. Roller and ball bearings are used with shafts that rotate at high speeds. Bushings have more contact area with the shaft and provide reduced friction. They’re a tight fit and usually pressed into the case. A special installation and puller tool is required for replacement. Today's automatic transmissions require several shafts. The two most notable are the input and the output shafts. Endplay is adjusted and controlled by selective thrust washers. Some thrust washers Torrington bearings contain needle bearings.
Ball Bearings: Ball bearings are capable of withstanding both radial and axial loads. They consist of steel balls that are kept separated from each other by a cage that rides in a groove in a hardened steel race. These bearings are used with high speed applications.
Roller Bearings: Roller bearings have more surface area than ball bearings. This property makes them well suited for heavy applications. Tapered roller bearings are found in differentials, final drives and transfer shafts. Tapered roller bearings require a slight preload. Always check with vehicle manufacturer's specifications before setting preload on a tapered roller bearing.
Needle Bearings: Needle bearings consist of small needle like bearings. They’re held in a round cylinder by assembly grease. Be careful when handling needle bearings, because they’re not fastened to the cylinder and easily fall from the carrier. Use petroleum jelly or Vaseline to hold the bearings that have fallen from the case. Never use white, chassis or bearing grease when installing bearings or washers in a transmission. These greases do not mix well with automatic transmission fluid.
Torrington Bearings: A Torrington bearing contains the needle bearings in a cage. They’re also known as caged needle bearings. These bearings are placed in a spoke pattern like a bicycle wheel inside of a thrust washer. They reduce friction and control shaft endplay.
Bushings: Bushings are brass or soft metal cylinder shaped bearings. This is because the bushing will wear before the hardened steel shaft. These bearings are usually pressed into the transmission case. Many transmission bushings contain a small oil hole that must align with the oil passage hole in the case.