general curiosity

Discussion in 'Transmission & Driveline Topics' started by balloonpilot, Jun 8, 2020.

  1. balloonpilot

    balloonpilot New Member

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    The members here have been so helpful and the information here is so extensive I thought I would ask a general information question of the group.
    Why do automatic transmissions get so much hotter than manual?
    You almost always have a automatic trans cooler or at least cooling lines going to the radiator, never a manual trans cooler (at least as far as I know of).

    Thanks in advance.
     
  2. Gary S

    Gary S Administrator Lifetime Gold Member

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    Automatic trannys are fluid drive. There is no mechanical connection between the engine and the rear end. Using fluid to move the rear wheels results in lots of heat and lost power. Flowing fluid is a very inefficient way to move something and all the lost power is heat.
    Manual trannys are direct mechanical drive between the engine and the driveshaft so no lost power and heat. Engine turns and driveshaft turns equivalent amount.
     
  3. Twisted_Metal

    Twisted_Metal Administrator Staff Member Lifetime Gold Member

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    ^ Yup!

    Clutch VS Torque Converter.
    A manual transmission only sees engine power when the clutch is engaged.
    An automatic is being heated continuously with the torque converter and pump physically agitating the fluid.
    With a higher stall converter, there is even more heat . And an additional cooler is recommended.

    The output of the engine is turned to heat when the car isn't moving and there is always some slippage within the torque converter, even when it is moving.
    (Unless you are up to speed and have a locking converter, which has a clutch inside of it. The locking converter does create a mechanical link between the engine and pump within the transmission with that internal clutch.)
     
  4. balloonpilot

    balloonpilot New Member

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    I knew I would get an answer here.

    Thanks guys
     
  5. badazz81z28

    badazz81z28 Veteran Member

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    Yeah. Friction, compression...creates heat
     

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