Z06 Gearing Makes Little Sense
 

What is the point of having 8 gears in Z06 if only gears 1-5 are utilized for acceleration to top speed and gears 6 and 7 are being used as overdrive gears? Why did GM choose to not maximize the acceleration potential of this car?

Naturally, we expect the last gear (8th) to be an overdrive gear. But three overdrive gears?

In comparison to that of some other high-powered modern cars, the gear spacing on Z06 makes little sense. Here is C8 Z06 gearing:

1st — 44 mph
2nd — 73
3rd — 105
4th — 145
5th — top speed (196 theoretical; car tops out at 195 mph)
6th — 252 mph (theoretical)
7th — 322
8th — 389

Source:
There’s a great web site* out there that will display gearing and speeds for any car. Link is below.

It’s fun and useful to check all sorts of cars. For example the Ferrari 458/Speciale and 488 have a VERY CLOSE ratio 7-speed gearbox with 7th gear used to achieve both top speed and overdrive. Some other modern cars with high horsepower are also worth a look such as BMW M8 Competition, Cadillac CT5 Blackwing, Ford Mustang Dark Horse, Mercedes AMG GT63S E-Performance, Porsche Panamera Turbo S E-Hybrid, etc.**

In consideration of cars like the ones mentioned above — and especially the two Ferraris mentioned — my opinion is that the C8 Z06 gearing should be something like this:

1st — 40
2nd — 60
3rd — 84
4th — 108
5th — 132
6th — 160
7th — 182
8th — 210 (theoretical; car reaches top speed of 195mph)
Z06 already has a gas guzzler tax — it doesn’t need to have a super crazy overdrive gear.

Naturally, this thinking assumes the intention is to maximize acceleration, which is precisely the purpose of having big horsepower and transmissions with 7+ gears. Mine isn’t a “perfect” suggestion about gear spacing — it’s just an example.

Sure, we could get into lengthy technical discussions about how the naturally aspirated, high-revving engine has something to do with choice of gearing, but the general point — which is that only 5 of 7 available gears were chosen by GM for maximum acceleration (with the 8th gear as overdrive) — stands on its own.

If you’re listening, GM, maybe give us a facelift car in 2026 with revised gearing — and why don’t you also clean up your act with the transmission in general.

* www.automobile-catalog.com (I am neither affiliated nor giving the site a plug)

<https://www.automobile-catalog.com/car/2023/3050315/chevrolet_corvette_z06.html>
Click “View this Car’s Detailed Specs”

** Attached photos reflect the gearing of these cars.

https://cimg0.ibsrv.net/gimg/www.cor...7983ff058.jpeg


https://cimg6.ibsrv.net/gimg/www.cor...dd7fc8b1e.jpeg
https://cimg1.ibsrv.net/gimg/www.cor...a20b446e9.jpeg
https://cimg2.ibsrv.net/gimg/www.cor...2f564feb1.jpeg
https://cimg3.ibsrv.net/gimg/www.cor...f4fd037b1.jpeg
https://cimg4.ibsrv.net/gimg/www.cor...1bf68f070.jpeg
https://cimg5.ibsrv.net/gimg/www.cor...c322400fe.jpeg

https://cimg7.ibsrv.net/gimg/www.cor...d0cb05343.jpeg

I think the intention was going around a track fast. gears 1-5 does that great. 6-8 are purely to get halfway decent mpgs on the way to the track.
I am sure GM has many, many ppt slides dedicated to gearing decisions....

Chevy stayed with the Stingray transmission ratios to save $. Tadge indicated the top speed of the C8Z would be between 205 and 212, before it got saddled with the Stingray gearing. Top speed is 195-196 as that is redline in 5th gear and shifting to 6th is like the C6Z, overgeared so it looses speed. Better gears in 4-6th would give better road course gears, get you top speed at/near redline in 6th and still have 7th and 8th be economy gears.

Man that's a very intelligent post. Thanks for the effort and research.

What Dave said... Tadge's comment about the intended top speed tells us everything.

3 overdrive gears? Try 5 man. 4th is 0.88:1 and it goes on from there.

This car would have significantly better acceleration and would be even more impressive with a more logical gear spread and one where the top of 7th would take you to top speed using 8th as overdrive.

Solution .... have someone like 'Hewland'' make you a custom set of gear ratios, or use one of their transmissions.

Why hasn’t anyone come out with gearing ratios to achieve this they do everything else lol

The reasons are many. Nobody has cracked the TCU encryption yet for starters. Second is probably the sheer cost of these units. What tuner has the resources to buy several Tremec DCTs (if they could even source them as Chevy main dealers seem to have trouble getting them) for testing and potential destruction? The cost we are taking about here probably makes physical gear changes a 5-figure proposition at minimum. How long would the line of customers be to spend that kind of money to void their warranty on most likely the whole powertrain (or the DCT at a minimum)? I hope somebody does it but I'm not holding my breath.

The main reason is the regular C8 has gearing to avoid the gas guzzler tax and help the CAFE (corporate average fuel economy) and the Z06 inherited these.

This car needs to hit Vmax at the top of 8th gear. Period!

Lol are you suggesting those that paid 150k ++++ cant afford to buy proper gearing? GMFAB!

It took nearly 10 years for the aftermarket to come out with replacement dif gear ratios for the C6Z, OEM was 3.42 and the aftermarket did 3.90 and 4.10. That was a simple job compared to what it will take to do new DCT gears for the C8Z, so likely NEVER HAPPEN.

Wouldn’t it be grand if a highly reputable tuner with a 2-year business plan on this got together with about 100 of us guys… we put up $1,000 each for a first round of financing. He puts in his own $15k. Any moneys not used come back to us later. Second round of financing maybe $500-$1000 more from the original 100 financiers or maybe harvest new owner-financiers. Financiers get preferred pricing on the eventual product to try to recoup some of the original investment. He targets maybe 100 of these transmission installations in the first year. That’s between 2 and 3 per week for 46 weeks.

The concept could also incorporate base C8 gear changes (albeit maybe with different gears, but same overall concept and packaging), so now we are talking a larger candidate pool. The eventual product could be licensed and sold to various installers across the country. Maybe 500 per year are installed. I think this is a scalable idea.

I am not intimately familiar with the process of getting a project like this off the ground; but I did recently drop the transmission out of my 2016 Porsche Boxster Spyder for a re-gear of the transmission (gears 2-5 are new with new main shaft; gears 1 and 6 stay the same. The new gears are better, stronger.).
The tuner involved is well-known Porsche shop and got this kind of project off the ground several years ago. (Incidentally that reinstallation happens next week - I’m super excited. Second gear to 84 mph from the factory in a 375hp car is ludicrous.)

Or we could just convince GM to do it.

I think you'd be quite surprised at the demographics of Corvette buyers, even the higher trims. A lot of those buyers at $150K are quite a bit more price-sensitive and risk-averse then you might think. It isn't just the out of pocket cost for the gearing changes should such a thing be possible. It is also the voided warranty on an already problematic gearbox. All of these z06s are still under warranty, I don't see a flood of owners ready to take that leap of faith into the great unknown. If anything drives it, it will be those 2020 and 2021 cars that are out of warranty cover.

I've mucked around with gear calculators and I think it can be fixed with just a proper 4th and then you make the old 0.88 4th the new 5th, the 0.65 5th becomes the new 6th and take your pick on those last two ratios. Swapping a single cog and tuning might not be too exorbitant.

No one has come out with different gear sets for the C5, C6, C7 transmissions yet, why does anyone thing they would do it for the C8?

There are many highly successful businesses on and off this forum that love their Corvettes. If it made business sense, they would already be going down that path. Apparently, there is a ton of money to be made according to those on here that haven't put the investment up to do it.

A more likely scenario for someone so inclined would be to put the sequential transmission from the C8R or GT3 car.

I for one don’t actually think anyone would attempt a new gearing project. Not in the near future. It’d be a massive undertaking and a significant risk for a labor of love. We have here just a topic of conversation within the general thrust of this thread, which is to complain about the gear ratios and to discuss the matter.

Fact is, GM is earning literally millions in net profit per week on the Z06 without even talking about base C8 income. While they couldn’t have imagined the post-Covid boom back in 2015-2019 when engineering C8, they did leave significant acceleration and performance in general on the table by not optimizing the acceleration potential of the car through a logical choice of gears.

I would go for it, but the availability of good aftermarket parts and support needs to mature. Swapping in a custom built DCT necessitates ECM reprogramming and this will nullify your warranty. This could potentially raise the cost of ownership by quantum leaps.

Once you go down the path of ECM reprogramming, I would want the eLSD revamped and support for two low pressure fuel pumps with separate bank to bank fueling control. This would make the C8Z06 a real world class supercar that would be fun as hell to drive.

Might as well do a manual….