Hunter of Trolls
Join Date: Nov 2012
Location: east coast
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the t/c locking simply places all the effort on the engine, and removes the fluid coupler (torque converter) from duty, for all practical purposes.. it's still there, obviously, but the engines crank and the input shaft of the trans has been mechanically locked.
there are several different types of stall... the stall that you're feeling when the t/c LOCKS is what's referred to as 'flash stall', or 'flare stall'...
I like using a bucket of water and a paddle as my examples of 'splaining this.. if you have said bucket of water in front of you with a paddle stuck in it, and you start twirling that paddle- the time it takes for the water to start swirling in the bucket at the same speed you are spinning the paddle describes flash stall.. *you may spin that paddle four or five revolutions before the water matches speed..
while your t/c is UNLOCKED, you feel a softer 'hook up', because the fluid (atf) is absorbing the change in torque (spinning power)... when it LOCKS, every bit of power the engine produces is being delivered to the input shaft of the transmission, which may be a good thing (if you're slightly under-loading the engine) or a bad thing (you're bogging it down and it's struggling to achieve RPM's because of that)....
in a 1/4 mile run, you're a lot better off allowing the t/c to remain unlocked in order to build those RPMs and have it translate to input shaft spin... when it does lock, later down the track, those extra RPM's will be translated to extra speed (or your perceived 'hook up') because all the initial effort to get that thing rolling has been satisfied, and inertia becomes your friend.
*- better torque converters, or ones that are designed for a specific purpose and not a wide range of function are more efficient, and can lower the flash/flare stall to almost nothing- but at the cost of generating a lot of heat.
Last edited by drewactual; 04-04-2014 at 10:15 AM.