2015 A8 torque convertors
Former Vendor
Joined: May 2007
Posts: 108
Likes: 4
Thought I would help out with some OE pics of the new 8L90 converter. It is what I call a twin disk lock up clutch, basically a double sided clutch for more holding capacity - same as the 2014 6L80 C7. It is what GM is calling a dual face clutch. The converter still has the Pump/Stator/Turbine for the fluid drive of the converter just like the 6L80 and 4L60 conventional converters. The big upgrade for this converter is the dual damper design, able to absorb more drive line NVH so they can bring on the clutches even earlier and slip them more. Essentially a damper attached to a damper, very cool design. Definitely going to be a challenge for the aftermarket to manufacture the hardware and then capability to tune a performance stall converter for the 8L90. We will figure it out, just give us some time.
Chris
Chris
Last edited by Circle-D; Jan 21, 2015 at 09:43 AM.
Race Director
Joined: Jul 2007
Posts: 10,961
Likes: 2,643
From: Texas Hill Country
ALSO------Here is a magazine article where both GM C7 transmission engineers were interviewed---
They describe the new innovations on both the manual trans and auto
GM actually calls the converter a "DUAL FACE CLUTCH"
But are careful not to call it a dual clutch because it is not-- But is a very close version----
EFILIVE on the other hand calls it a "CLUTCH TO CLUTCH" (as I maintain) again not dual clutch on purpose beacsue it is not but more similar in verbage to "DUAL FACE" as GM describes.
A dual clutch converter uses 2 separate clutch plates
A clutch to clutch or dual faced converter uses 1 plate with clutch material on both sides
http://www.superchevy.com/how-to/131...rack-mode.html
They describe the new innovations on both the manual trans and auto
GM actually calls the converter a "DUAL FACE CLUTCH"
But are careful not to call it a dual clutch because it is not-- But is a very close version----
EFILIVE on the other hand calls it a "CLUTCH TO CLUTCH" (as I maintain) again not dual clutch on purpose beacsue it is not but more similar in verbage to "DUAL FACE" as GM describes.
A dual clutch converter uses 2 separate clutch plates
A clutch to clutch or dual faced converter uses 1 plate with clutch material on both sides
http://www.superchevy.com/how-to/131...rack-mode.html
Thought I would help out with some OE pics of the new 8L90 converter. It is what I call a twin disk lock up clutch, basically a double sided clutch for more holding capacity - same as the 2014 6L80 C7. It is what GM is calling a dual face clutch. The converter still has the Pump/Stator/Turbine for the fluid drive of the converter just like the 6L80 and 4L60 conventional converters. The big upgrade for this converter is the dual damper design, able to absorb more drive line NVH so they can bring on the clutches even earlier and slip them more. Essentially a damper attached to a damper, very cool design. Definitely going to be a challenge for the aftermarket to manufacture the hardware and then capability to tune a performance stall converter for the 8L90. We will figure it out, just give us some time.
Chris
Chris
Safety Car
Joined: Nov 2002
Posts: 4,168
Likes: 1,336
From: FLL Florida
LaFerrari's DCT stays alive with spirited driving buy engine management. I don't see why the TC clutch in the C7 can't stay engaged in Sport mode at all times with fuel interruption only during shifts, especially with DI. This will keep temps down.
No reason that it can't run like this Yamaha tranny.
https://www.youtube.com/watch?x-yt-t...84359240#t=191
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
Thought I would help out with some OE pics of the new 8L90 converter. It is what I call a twin disk lock up clutch, basically a double sided clutch for more holding capacity - same as the 2014 6L80 C7. It is what GM is calling a dual face clutch. The converter still has the Pump/Stator/Turbine for the fluid drive of the converter just like the 6L80 and 4L60 conventional converters. The big upgrade for this converter is the dual damper design, able to absorb more drive line NVH so they can bring on the clutches even earlier and slip them more. Essentially a damper attached to a damper, very cool design. Definitely going to be a challenge for the aftermarket to manufacture the hardware and then capability to tune a performance stall converter for the 8L90. We will figure it out, just give us some time.
Chris
Chris
Racer
Joined: Jan 2015
Posts: 353
Likes: 25
From: san jose ca
No, it is not called a "clutch to clutch torque converter" It's called a "squashed" torque converter because it has a "flattened" appearance compared to "old style" torque converters. What you're referring to is the clutch to clutch shifting architecture of the transmission itself when it changes gears. Basically, everything in your post is BS.
There is a lockup clutch inside the torque converter that engages as early as 2nd gear that eliminates the "slower/sloppier" action you're talking about. GM uses a pulse width modulated signal to release/engage the lockup clutch at low RPM to allow as much as 100 RPM "slippage" to eliminate the vibrations from AFM. GM has used this feature for over 20 years. Porsche finally copied the GM design for their PDK to allow slippage of the clutch at low RPM to eliminate vibrations.
There is a lockup clutch inside the torque converter that engages as early as 2nd gear that eliminates the "slower/sloppier" action you're talking about. GM uses a pulse width modulated signal to release/engage the lockup clutch at low RPM to allow as much as 100 RPM "slippage" to eliminate the vibrations from AFM. GM has used this feature for over 20 years. Porsche finally copied the GM design for their PDK to allow slippage of the clutch at low RPM to eliminate vibrations.
Cunningham motorsports says they can unlock the A8 to make it shift faster. they did it with their maro.
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Verdad Gallardo
Team Owner
Joined: Apr 2001
Posts: 54,204
Likes: 180
From: S.W. Ohio. . . . . . NRA Life Member
Rather than copying the converters used in foreign super cars (which are very pricey) and are called a "dual clutch" design...
DualClutchTrannies are not automatics; they are manual transmissions with solenoid operation (making them appear to be autos). The clutches are also solenoid operated; one for odd numbered gears, the second for even numbered gears.
Although the DCT it is a manual transmission at heart, there is no torque lost during shifts, as both clutches are kept engaged during the very quick shift sequence.
Last edited by Mike Mercury; Oct 23, 2017 at 11:29 AM.
Le Mans Master
Joined: May 2000
Posts: 8,729
Likes: 1,508
From: Redmond WA
So it's not like I sit around saying "When we get a real DCT then we'll finally be able to..." because I don't actually know how to complete that sentence!
as both clutches are kept engaged during the very quick shift sequence.
Last edited by davepl; Oct 21, 2017 at 11:55 AM.