Piston Slap: Of manual transmissions in C8 Corvettes and Supras


Christopher writes:

What manual transmission would fit into a C8 Corvette? How about a manual in a 2021 Toyota Supra 3.0?

Sajeev answers: 

This is a fun and thought-provoking question; I love it! I think manual transmission swaps will become increasingly popular in internal combustion vehicles, as they transition away from being traffic-inducing smog factories during rush-hour commuting to a dedicated mode of transport for enthusiastic drives designed for nothing more than enjoyment. Because if you want to lose to an EV with 800+ horsepower, all-wheel drive, and unassailable handling characteristics, you want to have fun doing it, right?

Joking aside, darn near any manual swap is doable with metric tons of money and labor. And hours of homework before starting anything! On the Supra, have a look at the photo above, as you will need a Euro-spec BMW Z4 2.0i for parts. If the 2.0-liter-only, six-speed manual is too weak for a 3.0-liter mill, you might be forced to only grab the pedal assembly, shifter/linkages, NVH parts (i.e. things like rubber boots), and console trim from a donor Euro Z4. The trim parts will be challenging, but fusing Toyota and BMW plastics together will likely create the finished product you so desire. And perhaps the 2.0 transmission can be upgraded internally to handle the 3.0’s torque output. Or perhaps it’s fine as-is?

Let’s assume the 2.0’s manual can handle a 3.0 Supra, but no matter what, you’ll need a computer re-flash to get the car talking to the new gearbox. And that’s another expert you’ll seek online for counsel.

Or perhaps give the folks at EAG a wheelbarrow full of money and let them make it happen on your Supra? Whatever works for you!

2022 Chevrolet Corvette C8 Stingray center console detail
Cameron Neveu

The C8 will be far more difficult, as there’s no platform-mate with a manual to borrow things like a bolt-in pedal assembly. But since they use a LS/LT small block Chevy motor, odds are the fine folks at Ultima Sports Ltd. already found a way to adapt a Porsche transaxle to the C8’s engine. Will cubic money be involved in getting them to share their trade secrets? Yes.

Then again, maybe someone like Weddle Industries can make this happen with less pain. Once the bellhousing adapter is sorted, spending the time and money to fabricate a functional set of pedals, a shifter/cable subsystem, powertrain mounts, and ECU tuning will net amazing results. Perhaps someone can scan the C8’s console trim plate, then engineer/3-D print a new one that incorporates a manual transmission shifter/boot. Odds are the wiring harness for all the switchgear will need a bit of work too, but that’s what extra plugs and lengthening wires are for. Oh, and any holes drilled to get shift linkages and/or wires back to the transaxle will likely need reinforcement to ensure the C8’s integrity remains intact. You know, easy stuff like that. 

Sigh, this is getting far too complex for most of us. But who knows, when done this can be replicated as a kit, one that others will pay big money for. I see a nice little revenue stream for the forseeable future for anyone crazy bold enough to make this happen for C8 owners. There’s a pretty good chance that General Motors will never offer a stick shift again, so you’ll have no competition. Well, until someone comes out with their own kit by ripping yours off, and offshoring the production on a scale most folks can’t fathom. But hey, ’twas better to have loved and lost than never loved at all, right?

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    I suggest buying a 2023 Supra with factory manual transmission.

    Though the thought exercise was fun. Credit to Sajeev for putting the work in.

    With enough money you can do nearly anything. But in this case you literally would need to rebuild the entire car an re engineer some of it,

    The car was built with a center spine tunnel that was not intended to be cut into for a shifter. In cutting it would lead to weakening of the chassis and failure.

    GM clearly addressed this and it is not recommended.

    In changing it the car would also be slower and need a complete re do of the engine computer programming.

    So the simple answer to the average person is no it can’t be practically done.

    I suspect your prognostification of dinosaur ICE vehicles getting flogged on the streets by 800+ HP EVs might be a bit premature. When a Nissan Leaf struggles to deliver 300 miles of range, I can’t see some of these high HP monstrosities getting much more than 50 miles if the full force of their potential is utilized on the streets. I suspect these EVs will see more miles getting shuttled back and forth to Barrett Jackson auctions than they will ever deliver on pavement. I also suspect that when Johnny Law figures out that these things are having the opposite effect on global dinosaur consumption than intended, their outputs will be curtailed by law (corporate average amp-hour limits or something to that effect)

    As far as manual conversions, I was chatting with a friend about one of my ideas of converting a late-90s Buick Regal/Century to RWD for the ultimate sleeper, and he sent me a picture of someone who had mated an LS to what appears to be a Porsche/VW ilk transaxle by means of an adapter plate. I would post the pic, but thanks to the death of Community, not possible. I think manual conversions really depends on the depth of your pockets and your tenacity

    Re: prognostification, maybe on an organized scale of street racing on a larger scale, but I’ve already seen a used Tesla with paper tags racing a Charger on city streets and kicking its butt. And if I just randomly saw it once on the way home in the middle of the night, it’s happening on a regular basis…at least in cities with a street racing problem, and a population that can afford the monthly note on a 20-50k used car.

    You don’t need to be flooring them all the time to make the point, just one burst to 50mph on most city streets and your detractors wind up learning their place.

    You bring up another good point: at some point these luxury EVs will need something akin to a Gas Guzzler tax, as they are electron guzzlers in the same vein.

    While you aren’t wrong DUB6, I don’t miss all the technical glitches that kept me from writing and/or doing a deep dive to see just how feasible it is to swap manual transmissions in modern cars.

    GM considered a manual option while developing the C8 Corvette. It could have been a ‘simu’ configuration using an added shift lever and left pedal connected to mechanical parts by wires and software. Ultimately, that idea ended after considering the fact that few C7 customers signed up for the stick shift choice.

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