Automatic Transmission

The automatic transmission is a pretty incredible device when you get a chance to look inside of it.  The technology that is needed to eliminate manual shift transmission needs to have electronics and hydraulics to work in unity.  The transmission fluid flows throughout the whole transmission like oil in an engine.  It cleans, lubricates, cools and actuates the different assemblies that cause the automatic shifting to occur for thousands of miles. Rubber seals, gaskets, shift valves and clutches all must perform their jobs flawlessly or the automatic transmission is useless.

Automatic transmission fluid change intervals are much longer than that of engine oil since the fluid is not exposed to the high heat and combustion gases that engine oil is constantly dealing with.  The transmission fluid does break down due to the physical stress placed on it during normal operation.  As it wears it can no longer protect the seals, clutches and such that it is supposed to protect.  The detergents will weaken, allowing a varnish type material to start coating the hard metal parts and cylinders inside the unit.  Seals that are in place to control the flow of the fluid or lock up clutches start to harden with age, allowing fluid to leak by not applying the proper forces needed for good shifts.

When the transmission is serviced in many of today’s vehicles, the main transmission pan is dropped, allowing for some of the transmission fluid to come out of the unit.  This can amount to four or six quarts of fluid leaving another four or more quarts still remaining in the transmission.  So only about half of the fluid may really be changed normally during this service. If an automatic transmission exhibits any symptoms such as soft and sloppy shifts, shifts that are very firm and harsh, or slow engagement when placed in drive or reverse these can all be the result of a transmission’s normal wear.   Because of the construction of the automatic transmission out of many individual parts, leaks can also occur at many different locations.  Many seals and gaskets are used in the building of the transmission.  As they wear and age, leaking can occur.  If the leakage is great enough to lower the fluid level substantially, erratic transmission operation will occur with major internal damage to follow.