Quote:
Originally Posted by dwarfnebula
Many American made automatics allow you to coast in gear pretty effectively, they use a one way clutch (called a sprag) mostly because it allows for easier synchronization of engagement/disengagement in shifts. The side effect is that you can coast in gear, lots of GM transmissions won't engine brake at all in high gear. This is less the standard now than it used to be, in the early days all of them were like this.
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Do you mean in the trans. or in the torque convertor?
There is a stator and associated one way clutch in the torque convertor that is used to redirect the fluid velocity from the drive to the driven side of the TC, thus improving the efficiency of the drive across a range of speed difference between the engine and the trans. input shaft. The presence or absence of the stator defines the difference between a simple fluid coupling and a torque convertor.
There is also, almost universally these days, a lock up function where hydraulic pressure is use to clamp a clutch (Torque Convertor Clutch) inside the convertor and provide direct drive when slip is undesirable.
I suspect that what is happening is the TCC is being locked up creating a solid connection between the engine and trans. such as would be the case with a manual trans.. It might be educational to coast down to a speed at which the TCC disengages and feel the drag of the engine go away as the TCC is allowed to slip again.