Shifting question
Thread Starter
Burning Brakes
Joined: Jul 2005
Posts: 895
Likes: 459
From: Belleville Michigan
Shifting question
I've had this happen a couple of times that I've tried. At about 20 I pull it down to first hit it and seems to hit the limiter then go to second. Like it's a little late knowing what RPM it's at and forgets to shift?
Has anyone else had or tried this?
Has anyone else had or tried this?
E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
Posts: 35,106
Likes: 12,446
From: NE South Carolina
^^^
I know when in Manual Mode (where I intend to drive) it will NOT shift itself and will hit the rev limiter until you pull the upshift lever. In Auto Mode it is supposed to.
This is a list of what the DCT does or can do:·
I know when in Manual Mode (where I intend to drive) it will NOT shift itself and will hit the rev limiter until you pull the upshift lever. In Auto Mode it is supposed to.
This is a list of what the DCT does or can do:·
- The C8 DCT transmission has different automatic shift strategies for the various drive modes, which adapt in real time. The more aggressive, the more spirited you drive, the more aggressive the car's responds, -start to relax, the car starts to relax.
- The DCT uses latitudinal and longitudinal accelerometers, and looks at information like throttle position and steering angle to gauge how the car is being driven, and react accordingly. In Track mode set to automatic, the car will downshift aggressively when the driver is braking hard into a corner, and hold upshifts until corner exit.
- The C8 has two manual modes. If you pull a paddle while in Drive, you get a temporary manual mode, which automatically times out, or can be exited sooner by holding the upshift paddle. In this mode, the car will automatically upshift at redline. If you press the M button in the center console, you get full manual mode. There's no time out, and the car won't upshift at redline.
- Hold the downshift paddle, the DCT will serve up the lowest possible gear. Do that while braking, and the transmission will keep downshifting as engine speed allows.
- Pulling both paddles at the same time is equivalent to pushing in the clutch pedal on a manual car, which allows you to rev the C8's new V-8 as much as you want.
- The paddles are directly wired to the transmission control module (TCM) for quicker response times. This doesn't mean the paddles will give you a downshift that over-revs the engine—the TCM prevents that.
- With the C8's Performance Launch mode, the car uses the inertia of the engine coming down between revs to propel the car forward.
- ·You can avoid V4 mode using the “M” manual button or temporally for 5 seconds after pulling the last shift paddle. The new "Z" mode comes from the factory set up as an extra sporty mode including shift schedules pulled from the "Track" mode, so that will be V8 only. You can customize "Z" mode any way you want, so if you elect another shift pattern, V4 mode will return.
Last edited by JerryU; Aug 16, 2020 at 09:56 AM.
Drifting
Joined: Dec 2019
Posts: 1,310
Likes: 1,836
If you're in auto, and then manually shift down it assumes you want control and essentially goes into manual for a short time before going back to auto and shifting itself. It giving you time to shift yourself is probably the delay you're taking about.
Thread Starter
Burning Brakes
Joined: Jul 2005
Posts: 895
Likes: 459
From: Belleville Michigan
^^^
I know when in Manual Mode (where I intend to drive) it will NOT shift itself and will hit the rev limiter until you pull the upshift lever. In Auto Mode it is supposed to.
This is a list of what the DCT does or can do:·
I know when in Manual Mode (where I intend to drive) it will NOT shift itself and will hit the rev limiter until you pull the upshift lever. In Auto Mode it is supposed to.
This is a list of what the DCT does or can do:·
- The C8 DCT transmission has different automatic shift strategies for the various drive modes, which adapt in real time. The more aggressive, the more spirited you drive, the more aggressive the car's responds, -start to relax, the car starts to relax.
- The DCT uses latitudinal and longitudinal accelerometers, and looks at information like throttle position and steering angle to gauge how the car is being driven, and react accordingly. In Track mode set to automatic, the car will downshift aggressively when the driver is braking hard into a corner, and hold upshifts until corner exit.
- The C8 has two manual modes. If you pull a paddle while in Drive, you get a temporary manual mode, which automatically times out, or can be exited sooner by holding the upshift paddle. In this mode, the car will automatically upshift at redline. If you press the M button in the center console, you get full manual mode. There's no time out, and the car won't upshift at redline.
- Hold the downshift paddle, the DCT will serve up the lowest possible gear. Do that while braking, and the transmission will keep downshifting as engine speed allows.
- Pulling both paddles at the same time is equivalent to pushing in the clutch pedal on a manual car, which allows you to rev the C8's new V-8 as much as you want.
- The paddles are directly wired to the transmission control module (TCM) for quicker response times. This doesn't mean the paddles will give you a downshift that over-revs the engine—the TCM prevents that.
- With the C8's Performance Launch mode, the car uses the inertia of the engine coming down between revs to propel the car forward.
- ·You can avoid V4 mode using the “M” manual button or temporally for 5 seconds after pulling the last shift paddle. The new "Z" mode comes from the factory set up as an extra sporty mode including shift schedules pulled from the "Track" mode, so that will be V8 only. You can customize "Z" mode any way you want, so if you elect another shift pattern, V4 mode will return.
thanks
E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
Posts: 35,106
Likes: 12,446
From: NE South Carolina
^^^
Understand! If I drive as planned will be like my prior 2015 Z51 and 2017 Grand Sport and occasionally hit a wall at redline in 2nd!
Since I live in a rural area and don't like taking the Interstate into town, my 20 mile trip in both C7 M7s seldom got past 5th! Lots of turns and back roads past farm fields. Only used 7th the few times I would take the interstate and seldom found a need for 6th. So 6th in the C8, being close to 5th gearing in the C7 should be where I drive mostly. My normal downshift was directly to 3rd for turns, looks like I'll have to pull the downshift paddle twice!
Understand! If I drive as planned will be like my prior 2015 Z51 and 2017 Grand Sport and occasionally hit a wall at redline in 2nd!
Since I live in a rural area and don't like taking the Interstate into town, my 20 mile trip in both C7 M7s seldom got past 5th! Lots of turns and back roads past farm fields. Only used 7th the few times I would take the interstate and seldom found a need for 6th. So 6th in the C8, being close to 5th gearing in the C7 should be where I drive mostly. My normal downshift was directly to 3rd for turns, looks like I'll have to pull the downshift paddle twice!
Last edited by JerryU; Aug 16, 2020 at 10:40 AM.
Burning Brakes
Joined: Feb 2018
Posts: 927
Likes: 383
^^^
I know when in Manual Mode (where I intend to drive) it will NOT shift itself and will hit the rev limiter until you pull the upshift lever. In Auto Mode it is supposed to.
This is a list of what the DCT does or can do:·
I know when in Manual Mode (where I intend to drive) it will NOT shift itself and will hit the rev limiter until you pull the upshift lever. In Auto Mode it is supposed to.
This is a list of what the DCT does or can do:·
- The C8 has two manual modes. If you pull a paddle while in Drive, you get a temporary manual mode, which automatically times out, or can be exited sooner by holding the upshift paddle. In this mode, the car will automatically upshift at redline. If you press the M button in the center console, you get full manual mode. There's no time out, and the car won't upshift at redline.
E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
Posts: 35,106
Likes: 12,446
From: NE South Carolina
^^^
Interesting, explains the OP's question. But I just copied that info from what was posted by GM’s DCT Controls Manager with the V4 mode info from a Tadge Answers post added.
Interesting, explains the OP's question. But I just copied that info from what was posted by GM’s DCT Controls Manager with the V4 mode info from a Tadge Answers post added.
Last edited by JerryU; Aug 17, 2020 at 12:29 AM.
