DCT vs OTHERS
Thread Starter
Pro
Joined: Mar 2006
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From: EAST TEXAS
DCT vs OTHERS
My question is about various ways to get maximum accreditation off the line. For example, in a stick shift car, first, the engine RPM is brought up to a level well above idle, then simultaneously, the throttle is opened wide and the clutch is slipped. This takes advantage of the inertia of the spinning engine to get harder acceleration. In a torque converter system the brakes can be applied to prevent the car from moving while the throttle is opened. This causes the RPM to go up to stall speed. The same condition as a stick shift takeoff, that is, using higher than idle engine speed/inertia. Slippage is either by mechanical clutch or torque converter.
Now my question. How about a DCT, for those of you who are more familiar with the working of a DCT than I am, what is the scenario? If the brakes are applied and the throttle opened, does the controller allow slipping of the first gear clutch? Please provide more information.
Notice I did not mention CVT transmissions. I don’t know of any performance cars which have a CVT.
Now my question. How about a DCT, for those of you who are more familiar with the working of a DCT than I am, what is the scenario? If the brakes are applied and the throttle opened, does the controller allow slipping of the first gear clutch? Please provide more information.
Notice I did not mention CVT transmissions. I don’t know of any performance cars which have a CVT.
Race Director
Joined: Mar 2007
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At least two (or three depending on how you count them) ways to do that. Launch Control, Manual Launch, and also Rapid Exit from a double paddle de-clutch. In all cases the throttle pedal is (or can be) floored. And the the TCM will control the clutch engagement. Each is described in the Owner's Manual.
Thread Starter
Pro
Joined: Mar 2006
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From: EAST TEXAS
I should have been more specific. I am familiar with Launch Control. My curiosity is about the actual mechanical working in a hard takeoff.
I’m sure Launch Control does it more precisely, but what is actually happening with the throttle and clutch engagement?
I’m sure Launch Control does it more precisely, but what is actually happening with the throttle and clutch engagement?
Instructor
Joined: Aug 2025
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I have wondered the same thing? I assume the DCT trans clutch must be slipping and some wear is occurring. Might take a Tremec Engineer to explain how this works? Maybe with the throttle at 3500 rpm and the brake depressed past some pre-set limit, the DCT allows free spinning on a non-slipping (no wear occurring) clutch. Then when you release the brake the clutch engages. Since the DCT can transfer over 800 ft-lbs of torque, it doesn’t hurt (wear in a degrading manner) the DCT. It would be good to know if using launch control is wearing out the DCT.
E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
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From: NE South Carolina
I have wondered the same thing? I assume the DCT trans clutch must be slipping and some wear is occurring. Might take a Tremec Engineer to explain how this works? Maybe with the throttle at 3500 rpm and the brake depressed past some pre-set limit, the DCT allows free spinning on a non-slipping (no wear occurring) clutch. Then when you release the brake the clutch engages. Since the DCT can transfer over 800 ft-lbs of torque, it doesn’t hurt (wear in a degrading manner) the DCT. It would be good to know if using launch control is wearing out the DCT.
With no details but when the C8 was introduced, GM’s Chief Engineer, Ed Piatek said: “We found that during very aggressive launches we can drive torque through both shafts/clutches simultaneously which improves the 0 to 60 times.”
Road and Track interpretation of that statement was: "With the C8's Performance Launch mode, the car will actually use the inertia of the engine coming down between revs to propel the car forward. Chevy calls these "Boosted Shifts," and they're only used with a Performance Launch."
Recently a Forum member, who's business involves the controls for EV's DCT's etc, @RedLS6 when I posted they must slip the clutches for a few milliseconds responded: For some DCT's it's "near 100 milliseconds" for their Launch Control. He did not have numbers for the C8 but that is what they are doing.
NOTE: For those who don't relate to milliseconds; 100 milliseconds = 0.1 seconds. For perspective:
Loss a ProStock drag race every time having that slow a reaction time at the start! Heck the Old Man (64) Greg Anderson cut a 0.013 light to win at Pomona (that I watched!) Erica Enders (who won NHRA ProStock world championships in 2014, 2015, 2019, 2020, 2022, and 2023) has an average reaction time of 0.032 (according to Google.) Was not unusual for her to cut a 0.00X light.
.Loss a ProStock drag race every time having that slow a reaction time at the start! Heck the Old Man (64) Greg Anderson cut a 0.013 light to win at Pomona (that I watched!) Erica Enders (who won NHRA ProStock world championships in 2014, 2015, 2019, 2020, 2022, and 2023) has an average reaction time of 0.032 (according to Google.) Was not unusual for her to cut a 0.00X light.
The C8 Launch Control is very significant. Prior to reaching >1500 miles on my E-Ray made many launches without Launch Control. Consistently got 2.5 seconds best 2.4 (GM Dash Test.) On the same section of street pavement, starting with same 100% EV battery, same heating my ZER Option Summer Tires prior, have achieved 2.1 seconds several times. The launch is incredible.
Without Launch Control can't start with 3500 rpm before releasing brake. I used the normal "automatic" foot on brake, WOT when releasing brake. No torque converter stall like my 8.2 Liter ProStreet Rod to get the engine spinning at >2500 rpm prior to brake release.
Last edited by JerryU; Sep 21, 2025 at 02:15 PM.
