C8 Corvette Transaxle

Good morning everyone. I have been counting down the days with anticipation until the new C8 Corvette was officially released. Having owned a corvette before, naturally I am a big fan and couldn't contain myself the moment the president of GM drove the car on stage. The Z51 performance package that was shown on stage comes with an 8 speed automatic dual clutch transaxle (DCT) with paddle shifters that helps get the vette to 60mph in under 3 seconds. For everyone that uses the LS series of engines, I imagine that it will bolt up quite nicely; however I wonder how everyone thinks it will fit in the SL-C. From the reveal it looks pretty compact to me, but the design is super complicated and there is a lot going in inside the transaxle. According to Hagerty, there will be two clutches, two power input paths, two gears for every forward speed along with their synchronizers, plus three gears to implement reverse. Pretty crazy. Down the road when i am finally able to pull the trigger on my own SL-C, i have planned on using the V8 Graziano with 1.038 drop gears, but depending on the cost of this transaxle it might be pretty cool to actually try this new option and be different. I know the gated shifter with the Graz has such a great feel and is probably a bit lighter but an 8 speed paddleshift sure does sound nice, especially with all of the traffic I am always having to contend with on the road. What are everyone else's thoughts on this? Here is the patent and design layout of the transaxle. Looks like it might fit to me!
 

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I'm guessing the biggest hurdle will be the electronics. The transaxle operation is going to be tied directly to engine function.....and my guess is that the only way to get it to work would be to have the ENTIRE electrical system from a C8.....or wait for GM to come out with a crate engine/transaxle package option.

Not much different than when they came out with the LS3. You could buy an LS3, but you could not buy the ECU to actually make it run. The only option was to use a C5 ECU and tear the engine down to convert back from a 58 tooth reluctor to 24 tooth.
 
Bah, be a manly man and stick a built 930 transaxle in there. Bestest transaxle ever. Weighs next to nothing, can be built to handle infinite torque and you don't really need more than 4 gears anyways.
 
That’s exactly right.

With everything that’s tied into the can-bus, you’d find yourself with unexpected items like a second instrument cluster and door handles in a box in your trunk (as the conventional-to-DFI Cayman conversions found) to get it to all function correctly if you tried to convert with a donor.

Even if you got all those sensors transferred over, you’d have to make sure they were calibrated correctly so that the traction and stability systems sent the all clear. Without it, it’s likely there’s a reduced power or rpm mode the motor/trans gets locked into. As I understand it, chassis-specific measurements factor into how the traction control works - so those measurements or ratios of those measurements would need to be the same, or tricked, or disabled without throwing something else off down the chain.

I don’t see Chevy ever offering this to the aftermarket due to complexity... and if they did it’ll be 10 years down the road.

I'm guessing the biggest hurdle will be the electronics. The transaxle operation is going to be tied directly to engine function.....and my guess is that the only way to get it to work would be to have the ENTIRE electrical system from a C8.....or wait for GM to come out with a crate engine/transaxle package option.

Not much different than when they came out with the LS3. You could buy an LS3, but you could not buy the ECU to actually make it run. The only option was to use a C5 ECU and tear the engine down to convert back from a 58 tooth reluctor to 24 tooth.
Everything was better with 70s alloys and machining technology!! ;-)

Bah, be a manly man and stick a built 930 transaxle in there. Bestest transaxle ever. Weighs next to nothing, can be built to handle infinite torque and you don't really need more than 4 gears anyways.
 
The last two sentences in this paragraph are promising.
The gearbox that ended up in the Corvette is a DCT designed and built by Tremec. It's meant to be quicker than a human but just as engaging. It also takes a page from the Graziano gearbox used by McLaren. The paddles are directly wired to the gearbox, there's no middle man. The car doesn't second guess you.
 
Best bet would be if GM Performance will release it for the aftermarket. They’ve done so with the automatic C7 ZR1 (selling both engine and trans together as a package). There’s no reason to believe they won’t do the same with the C8 Corvette DCT.
 
People in the UK have managed to get the Porsche PDK dual clutch box to work behind an LS in the back of an Ultima, and offer a package for builders.
 
People in the UK have managed to get the Porsche PDK dual clutch box to work behind an LS in the back of an Ultima, and offer a package for builders.
They did, but judging by the age of the gearbox platform used, this will be many years down the road. I also suspect the Corvette DCT will have more sophistication and be more involved to transplant.

Specific to the LS-PDK conversion - love the idea, but it’s hugely expensive, and uses a est 250tq Boxster/Cayman gearbox. If my information is correct, Porsche doesn’t sell replacement parts for them and the updated Dodson clutch is in the $8-10k range.
 
uses a est 250tq Boxster/Cayman gearbox. If my information is correct, Porsche doesn’t sell replacement parts for them
This may initially be correct, keep in mind that initially that spares for the Porsche 996 (G96 variant) gearboxes were not available either. I think while they are still under warrantee most things are covered by Porsche, its only once they get a little older that spares and tools become available. I doubt that Porsche will miss out on the opportunity to sell spare parts. if they don't make spare parts available, someone will step up and make the parts available aftermarket. the volumes are high enough world wide that parts will be movable. The same will probably apply with the C8, I doubt there is even a parts manual available to the public at this time.
 

Howard Jones

Supporter
I would think that the way to do this would be to buy a complete car that has been totaled (front end) and then use the entire power train, engine, grbx, and systems and install in a SLC. Even if you had to pay, $35- 40Kish for the wreck it would be worth it. The remaining useable pieces could be sold to offset some of that cost.

This way you have a complete electrical system to work with. Easy? No, but it could be done and I think it will be done this way sooner or later.
 
I would think that the way to do this would be to buy a complete car that has been totaled (front end) and then use the entire power train, engine, grbx, and systems and install in a SLC. Even if you had to pay, $35- 40Kish for the wreck it would be worth it. The remaining useable pieces could be sold to offset some of that cost.

This way you have a complete electrical system to work with. Easy? No, but it could be done and I think it will be done this way sooner or later.
Something to consider........this transaxle weighs in at double what a manual Porsche trans weighs. Then add the entire 'Vette harness, all of the control modules/computers, brackets to mount all of that stuff (that's not normally there).....and pretty soon, you have a 3,000 lb SL-C......which sort of defeats the entire purpose of having an SL-C?
 
I would think that the way to do this would be to buy a complete car that has been totaled (front end) and then use the entire power train, engine, grbx, and systems and install in a SLC. Even if you had to pay, $35- 40Kish for the wreck it would be worth it. The remaining useable pieces could be sold to offset some of that cost.

This way you have a complete electrical system to work with. Easy? No, but it could be done and I think it will be done this way sooner or later.
100% - that's exactly the way to do it. It would be a nightmare to get into a project like that, and find that you were missing a dozen sensors you couldn't source anywhere but a dealer.

Recalling some research into DFI Cayman swaps, you wind up needing unexpected parts to make these work. In the Cayman's case, the instrument cluster and door handles in addition to all the electronic controllers and sensors you'd expect. So in a car where you wanted an AIM or Motec dash, you'd need to have the OE stuff in a box somewhere.

This may initially be correct, keep in mind that initially that spares for the Porsche 996 (G96 variant) gearboxes were not available either. I think while they are still under warrantee most things are covered by Porsche, its only once they get a little older that spares and tools become available. I doubt that Porsche will miss out on the opportunity to sell spare parts. if they don't make spare parts available, someone will step up and make the parts available aftermarket. the volumes are high enough world wide that parts will be movable. The same will probably apply with the C8, I doubt there is even a parts manual available to the public at this time.
These are 987 PDK's, which were a mid 2000s through 2012 gearbox. I'd expect them all to be out of warranty at this point.
Out of curiousity, I just did a search and didn't turn up any replacement internals. Porsche typically supports their product extremely well, so not sure what's going on there.
 
Something to consider........this transaxle weighs in at double what a manual Porsche trans weighs. Then add the entire 'Vette harness, all of the control modules/computers, brackets to mount all of that stuff (that's not normally there).....and pretty soon, you have a 3,000 lb SL-C......which sort of defeats the entire purpose of having an SL-C?
I'd suspect there are more than a few SL-C that are near 3,000 lbs. Weight is weight, but really if you are not trying to win races on a track, what's the difference between a, 2,700 lb car and a 3,000 lb car?
 
While the gearbox is almost twice as heavy as a manual/sequential, it’s important to note that dual clutch transmissions transmit torque to the wheels constantly during upshifts, because as 1 clutch disengages, the other clutch is engaging simultaneously. Effectively shift time is like 8ms. The 100ms quoted by Tremec is due to electronic lag (TCM computer needs some time to synchronize the shifts when the paddle is pulled). Because of this behavior they are banned in most Motorsports like F1 , because they are considered CVT’s by the rules.
 
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