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Old 04-08-2015, 02:46 PM   #1
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Clutch in an automagic transmission?

So I was driving around the other day contemplating why I have a tiptronic boxster instead of a manual one, and I got to thinking: What would happen if you just replaced the torque converter in the car with a nice, solid clutch? I've never opened up the tranny before but wouldn't it work essentially the same way as a sequential gearbox? the internals would be completely different, of course, but would they work? shifts would probably feel hella thumpier but I assume if you had a true sequential gearbox it would feel about the same. I'm not seriously thinking about doing this but I found it an interesting concept. Has anyone ever done this? and finally, why don't any street cars have sequential gearboxes?

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Old 04-08-2015, 02:58 PM   #2
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A lot of guys do that to the 944
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Old 04-08-2015, 03:56 PM   #3
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Wouldn't it have to be a wet clutch?
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Old 04-08-2015, 05:02 PM   #4
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First without the torque converter there is no way to provide fluid pressure for the shifting. Then there would be the issue with loss of torque multiplication without the converter. Then somehow there needs to be a clutch pedal to operate the clutch...


You could always go the other way around and go with a SMG trans, where there there is a computer that drives the solenoids and hydraulic valves...

ie SMG for the BMWs


Still, either way, kind of expensive to be putting so much money in a old car.

Oh and yes clutches have been put into automatic trans in place of the torque converter, they were used to some success in drag racing in the late 60s

http://ggordon528.tripod.com/shop/cpe/clutchflite.html
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Old 04-08-2015, 05:26 PM   #5
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Isn't the PDK an automatic with a clutch same with Ferrari, the new Stingray and Hellcat?

I always wondered if a PDK could be put into a 986.
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Old 04-08-2015, 05:36 PM   #6
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Originally Posted by KRAM36 View Post
I always wondered if a PDK could be put into a 986.
Most likely, if the computer was connected into the 986 correctly. The double-clutch transmissions are pretty fantastic.
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Old 04-09-2015, 02:47 AM   #7
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Originally Posted by KRAM36 View Post
Isn't the PDK an automatic with a clutch same with Ferrari, the new Stingray and Hellcat?

I always wondered if a PDK could be put into a 986.
No, true "sequential manual gearboxes" (SMG) like the PDK or Ferrari use are actually a manual gear box that is shifted by a computer and uses dual wet clutches. GM and Chrysler still use an automatic transmission with a torque converter.

As for adding a PDK to a 986, with enough time, welding equipment, and money; anything is possible.
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Last edited by JFP in PA; 04-09-2015 at 02:52 AM.
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Old 04-09-2015, 02:48 AM   #8
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First without the torque converter there is no way to provide fluid pressure for the shifting. Then there would be the issue with loss of torque multiplication without the converter. Then somehow there needs to be a clutch pedal to operate the clutch...


You could always go the other way around and go with a SMG trans, where there there is a computer that drives the solenoids and hydraulic valves...

ie SMG for the BMWs


Still, either way, kind of expensive to be putting so much money in a old car.

Oh and yes clutches have been put into automatic trans in place of the torque converter, they were used to some success in drag racing in the late 60s

727 Clutchflite
God, I haven't seen an Art Carr Clutch Flite in years!
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Old 04-09-2015, 03:38 AM   #9
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Originally Posted by JFP in PA View Post
No, true "sequential manual gearboxes" (SMG) like the PDK or Ferrari use are actually a manual gear box that is shifted by a computer and uses dual wet clutches. GM and Chrysler still use an automatic transmission with a torque converter.

As for adding a PDK to a 986, with enough time, welding equipment, and money; anything is possible.
But it's still an automatic trans as it shifts for you with a clutch.

Porsche Cayman - Porsche Doppelkupplung (PDK) - Porsche North America

"Porsche Doppelkupplung (PDK)

Of course, you could let us take care of the gearshift strategy so that you can devote all your attention to your cornering strategy, with the optional 7-speed Porsche Doppelkupplung (PDK) featuring both manual and automatic modes. PDK offers extremely fast gear changes with no interruption in the flow of power, improved acceleration over the manual transmission, very short response times, reduced fuel consumption and a distinct increase in comfort."

You need to look into the Stingray and Hellcat some more, you're a little behind the time on those.

New 8-Speed Enables Quicker, More Efficient Corvette

"DETROIT – The all-new, GM-developed Hydra-Matic 8L90 paddle-shift eight-speed automatic transmission offered in the 2015 Corvette Stingray and Z06 enhances performance and efficiency, while delivering exceptional refinement and world-class shift responsiveness that rivals the world’s best dual-clutch transmissions."

Dodge - Build & Price -

TorqueFlite® Eight-Speed Automatic Transmission

2.62 Rear Axle Ratio
A numerically lower axle ratio results in lower engine rpm and better fuel economy. A numerically higher ratio improves acceleration, climbing grades, carrying loads or pulling a trailer.
AutoStick® Automatic Transmission
Leather-Wrapped Shift Knob
Remote Start System
Check state and local laws regarding use of remote start systems.
Steering Wheel Paddle Shifters
Tip Start
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Last edited by KRAM36; 04-09-2015 at 03:41 AM.
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Old 04-09-2015, 08:05 AM   #10
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Quote:
Originally Posted by KRAM36 View Post
But it's still an automatic trans as it shifts for you with a clutch.

Porsche Cayman - Porsche Doppelkupplung (PDK) - Porsche North America

"Porsche Doppelkupplung (PDK)

Of course, you could let us take care of the gearshift strategy so that you can devote all your attention to your cornering strategy, with the optional 7-speed Porsche Doppelkupplung (PDK) featuring both manual and automatic modes. PDK offers extremely fast gear changes with no interruption in the flow of power, improved acceleration over the manual transmission, very short response times, reduced fuel consumption and a distinct increase in comfort."

You need to look into the Stingray and Hellcat some more, you're a little behind the time on those.

New 8-Speed Enables Quicker, More Efficient Corvette

"DETROIT – The all-new, GM-developed Hydra-Matic 8L90 paddle-shift eight-speed automatic transmission offered in the 2015 Corvette Stingray and Z06 enhances performance and efficiency, while delivering exceptional refinement and world-class shift responsiveness that rivals the world’s best dual-clutch transmissions."

Dodge - Build & Price -

TorqueFlite® Eight-Speed Automatic Transmission

2.62 Rear Axle Ratio
A numerically lower axle ratio results in lower engine rpm and better fuel economy. A numerically higher ratio improves acceleration, climbing grades, carrying loads or pulling a trailer.
AutoStick® Automatic Transmission
Leather-Wrapped Shift Knob
Remote Start System
Check state and local laws regarding use of remote start systems.
Steering Wheel Paddle Shifters
Tip Start

Yes basically automatic transmissions, more so with the Dodge and gm trans as they use a traditional torque converter, planetary gears, and basically give the user more control over the shifting.

The Porsche PDK is less traditional and uses a nontraditional way of shifting the gears with a wet clutch.

The BMW SMG is essentially a manual transmission with a hydraulic lever actually pushing a clutch arm and servos changing gears.... its a beautiful sound to hear a SMG up shift and down shift esp with a aftermarket exhaust. The computer actually raises and lowers the engine speed to match each gear shift, so with each downshift comes a blip of the throttle. You also have to put the trans in gear and/or neutral with the parking brake when parking the car, otherwise risk the car rolling like a manual trans

The SMG trans has a typical clutch that wears like a normal clutch (if 40-60k miles can be considered normal) that needs to be replaced but no clutch pedal like a manual trans car.

In none of these transmissions is there a clutch pedal though.

Last edited by healthservices; 04-09-2015 at 08:20 AM.
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Old 04-09-2015, 09:04 AM   #11
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Originally Posted by KRAM36 View Post
But it's still an automatic trans as it shifts for you with a clutch.

Porsche Cayman - Porsche Doppelkupplung (PDK) - Porsche North America

"Porsche Doppelkupplung (PDK)

Of course, you could let us take care of the gearshift strategy so that you can devote all your attention to your cornering strategy, with the optional 7-speed Porsche Doppelkupplung (PDK) featuring both manual and automatic modes. PDK offers extremely fast gear changes with no interruption in the flow of power, improved acceleration over the manual transmission, very short response times, reduced fuel consumption and a distinct increase in comfort."

You need to look into the Stingray and Hellcat some more, you're a little behind the time on those.

New 8-Speed Enables Quicker, More Efficient Corvette

"DETROIT – The all-new, GM-developed Hydra-Matic 8L90 paddle-shift eight-speed automatic transmission offered in the 2015 Corvette Stingray and Z06 enhances performance and efficiency, while delivering exceptional refinement and world-class shift responsiveness that rivals the world’s best dual-clutch transmissions."

Dodge - Build & Price -

TorqueFlite® Eight-Speed Automatic Transmission

2.62 Rear Axle Ratio
A numerically lower axle ratio results in lower engine rpm and better fuel economy. A numerically higher ratio improves acceleration, climbing grades, carrying loads or pulling a trailer.
AutoStick® Automatic Transmission
Leather-Wrapped Shift Knob
Remote Start System
Check state and local laws regarding use of remote start systems.
Steering Wheel Paddle Shifters
Tip Start
It is more than a matter of semantics, if you saw the Vette or Doge trans out of the car, they have a torque converter, use pumps to generate pressure, planetary sets, sprags, pawls, and all the other stuff found in all automatic transmissions. If you saw the PDK out of a Porsche, it is not similar to the current seven speed manual, it is the seven speed manual, complete with gears, synchro rings and everything else you would find in a manual gear box, the big difference is that it uses a dual (one of even gears, one for odd) wet clutch system, and everything is controlled by computers, right down to "blipping" the throttle during down shifts.

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Last edited by JFP in PA; 04-09-2015 at 09:09 AM.
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Old 04-09-2015, 11:11 AM   #12
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I vote for this retrofit.




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Old 04-09-2015, 11:13 AM   #13
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Originally Posted by JFP in PA View Post
It is more than a matter of semantics, if you saw the Vette or Doge trans out of the car, they have a torque converter, use pumps to generate pressure, planetary sets, sprags, pawls, and all the other stuff found in all automatic transmissions. If you saw the PDK out of a Porsche, it is not similar to the current seven speed manual, it is the seven speed manual, complete with gears, synchro rings and everything else you would find in a manual gear box, the big difference is that it uses a dual (one of even gears, one for odd) wet clutch system, and everything is controlled by computers, right down to "blipping" the throttle during down shifts.

I wonder how long the Porsche clutches last and if they are replaceable like a torque converter or where the clutch and clutch plates are changed like a automatic
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Old 04-09-2015, 12:07 PM   #14
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I wonder how long the Porsche clutches last and if they are replaceable like a torque converter or where the clutch and clutch plates are changed like a automatic
Being "wet", they should last a long time, particularly as the computer prevents any abuse and steps in if you get out of control. Interestingly, Porsche parts does not even list the clutch pack as a separate component part, so it may only be available as part of a factory reman trans.
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Old 04-09-2015, 12:56 PM   #15
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That's a scary thought. Mr. Brown the your clutch is worn out.... that'll be $13,537 for the part and another 2300 for labor. But for your inconvenience we will provide a loaner car for the first two day we have it. Of course afterwards you will have to pay for the rental or use another form of transportation....
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Old 04-09-2015, 01:50 PM   #16
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That's a scary thought. Mr. Brown the your clutch is worn out.... that'll be $13,537 for the part and another 2300 for labor. But for your inconvenience we will provide a loaner car for the first two day we have it. Of course afterwards you will have to pay for the rental or use another form of transportation....
Don't laugh; when the PDK cars warranty runs out, that is pretty much what they face if the PDK goes south as very few parts are available, there is no info on how to repair them, and a reman costs more like $17K (just for the unit in a crate).
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Old 04-09-2015, 02:00 PM   #17
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Originally Posted by JFP in PA View Post
It is more than a matter of semantics, if you saw the Vette or Doge trans out of the car, they have a torque converter, use pumps to generate pressure, planetary sets, sprags, pawls, and all the other stuff found in all automatic transmissions. If you saw the PDK out of a Porsche, it is not similar to the current seven speed manual, it is the seven speed manual, complete with gears, synchro rings and everything else you would find in a manual gear box, the big difference is that it uses a dual (one of even gears, one for odd) wet clutch system, and everything is controlled by computers, right down to "blipping" the throttle during down shifts.

No, the Vette and the Hellcat do not have a torque converter. Did you bother to read the links I posted?

From the Corvette link

Quote:
With four simple gearsets for optimal efficiency and five clutches (two brake clutches and three rotating clutches), creative packaging enables the new eight-speed automatic to fit the same space as the previous six-speed automatic – and the powerflow only uses two open clutches for low spin losses, which enhances efficiency. Extensive use of aluminum and magnesium also make it more than eight pounds (4 kg) lighter than the six-speed.


and the Hellcat gets this transmission

ZF 8HP transmission - Wikipedia, the free encyclopedia



They are all automatic transmissions as they shift the gears for you. Porsche, Ferrari, Stingray, Hellcat, BMW, Lambo, Nissan GTR all of them are automatics using a clutch system.
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Old 04-09-2015, 02:31 PM   #18
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No, the Vette and the Hellcat do not have a torque converter. Did you bother to read the links I posted?

From the Corvette link





and the Hellcat gets this transmission

ZF 8HP transmission - Wikipedia, the free encyclopedia




They are all automatic transmissions as they shift the gears for you. Porsche, Ferrari, Stingray, Hellcat, BMW, Lambo, Nissan GTR all of them are automatics using a clutch system.
Sorry, but perhaps you need to re read them, from the Corvette article:

"Unique clutch and torque converter specifications matched to the torque capacity of the Stingray’s LT1 6.2L naturally aspirated engine and the Z06’s LT4 supercharged engine distinguish the applications for the different Corvette models."

And in the Doge article the transmission, with a torque converter clearly visible, as it is in the photo above.

They are both conventional automatic transmissions, not an SMG like the PDK.
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Old 04-09-2015, 02:55 PM   #19
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Yep you can plainly see it is a auto trans, only difference is heavier duty, and computer controlled, allowing buttons for shifting.
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Old 04-09-2015, 02:59 PM   #20
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Sorry, but perhaps you need to re read them, from the Corvette article:

"Unique clutch and torque converter specifications matched to the torque capacity of the Stingray’s LT1 6.2L naturally aspirated engine and the Z06’s LT4 supercharged engine distinguish the applications for the different Corvette models."

And in the Doge article is the transmission, with a torque converter clearly visible, as it is in the photo above.

They are both conventional automatic transmissions.
It's not the torque converter of the old days and a clutch shifts the gears on the Vette.

Quote:
The torque converter takes the place of a clutch on a conventional manual transmission
This Is How An Automatic Transmission Works

The picture of the trans for the Hellcat I used the wrong picture. The hellcat gets the wet multiplate clutch.


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