Dct question
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Joined: Mar 2006
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From: EAST TEXAS
Dct question
A question for my education. How does a DCT "de-couple" when at a stop. And when the throttle is opened to take off, and the engine RPMs rise how is the transmission engaed? Without a torque converter or manual clutch control, is there an internal controller which gradually engages the first clutch. And if so, what happens when a brake torque launch is used?
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Joined: Jan 2014
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From: Fulshear, TX
Computer controlled hydraulic clutches. You can't brake torque from a stop as the computer out-smarts the driver to protect itself (nor would you want to smoke the clutch discs like that). Use launch control for the "perfect" launch from a stop.
Thread Starter
Pro
Joined: Mar 2006
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From: EAST TEXAS
Thanks for the reply Kracka. A follow up question. For initial acceleration/torque to get off the line, a torque converter will let the engine rev up to the converter's stall speed, which increases the torque. With a manual shift, as the clutch is being released, the engine can be brought up to higher rpm to increase torque and use the mass of the flywheel to get more off the line grunt. So, on the DCT, is the first gear ratio lower than normal to allow the engine RPM's to come up quicker?
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Using launch control, with your foot on the brake, and the other with the throttle fully depressed, the car will let engine come up to a certain RPM. When you take your foot off the brake, the car will control the level of throttle (as you keep your foot on throttle fully depressed) and it will control the clutch engagement for optimal launch. Th answer to yor question is that the ratio of first gear was appropriately engineered for this exact situation (I don't know what "lower than normal" means).
