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Old 06-25-2012, 04:10 PM   #8 (permalink)
mort
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Quote:
Originally Posted by Banana Jack View Post
"The fluid coupling between engine and transmission is almost a one way street..."
This is wrong. The fluid coupling in virtually all automotive torque converters is symmetrical. What makes an automatic transmission coast when the selector is in D is that there is an over-running (one-way) clutch inserted in the drive train. This clutch is not part of the torque converter, it is inside the transmission. In L or 2 or 1 that clutch is disabled. Put the automatic in L and you'll feel the same drag as a manual transmission when you lift off the accelerator.
Most of the rest of the original quote is also incorrect. There is slippage in a torque convertor, and so most have internal lock-up clutches that eliminate that inefficiency.

-mort
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