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A Guide to Buying Complete Car and Truck Automatic Transmissions

A motor vehicle’s transmission is the assembly that delivers engine power to the vehicle’s driving axle. If a vehicle doesn’t have other issues, the more gear ratios a transmission has, the more smoothly that vehicle will run. If you’re looking for a reasonably priced automatic transmission for sale, eBay is the place to find it.

Types of automatic transmissions

Automatic transmissions are transmission assemblies capable of autonomously changing gear ratios as the vehicle accelerates and decelerates. This frees up the driver’s hands. These variations on the basic automatic transmission model are found in cars and trucks:

  • Fully automatic transmissions: Fully automatic transmissions change gears through the use of a hydraulic fluid coupling or a torque converter.
  • Semi-automatic transmissions: Semi-automatic transmissions combine the features of manual and automatic transmissions. They use a clutch and gear confirmation, but also rely upon sensors, actuators, and processors.
  • Continuously variable transmissions: Continuously variable transmissions are automated transmissions that don’t deploy traditional steel gears. Instead, power is transmitted from the engine to the driving axle by means of a pair of pulleys and a belt.

 What parts come with an automatic transmission assembly?

When you purchase an automatic transmission for sale, you should expect to find:

  • A torque convertor: The torque convertor is the hydraulic fluid coupling that connects the engine to the transmission. Its parts include a stator, an impellor, and a turbine.
  • A planetary gear set: The planetary gear set determines all the gear ratios that your car or truck will use. It consists of a sun gear, various planetary gears, and a ring gear.
  • A pump: The pump is located between the torque convertor and the planetary gear set. It draws and pressurizes the transmission fluid. Automatic transmissions rely heavily upon fluid pressure to function.
  • A valve body
  • Clutches: Clutches allow pressurized fluid to push pistons. When these pistons are engaged, power is sent to the wheels.
  • Bands: Bands wrap around the gear train, tightening or loosening depending upon whether gears need to be engaged or disengaged.

 What should you look for when you’re buying used automatic transmissions?

Find out as much as you can about the history of the vehicle from which the transmission was stripped before you buy it. If you can, obtain the VIN of that vehicle, which may be able to help you research any past transmission-related accidents the vehicle may have been involved in.