marcouvo

Will the 2015 C7 Automatic be the new A8 or the existing A6?

Vetteman Jack

I hope it will be the A8, but GM may wait a year after the intro of the Z06 to offer it in the other models.

SCM_Crash

No reason for them to make two transmissions. Just like they've done with lots of other upgrades, it's more likely that the A8 will be shared among all the trim levels.

It's simply cheaper to mass produce one transmission even if it's slightly more expensive, than produce two that adds an extra option on the assembly line.

Carnut12

Exactly, they would not spend all that money producing it and only put it in the Z06, I bet a variation of it ends up in many of their vehicles including the C7, but IMO they will wait until 2016.

9157

With that logic...they would. Only produce one engine!!! My dealer is saying Gm wants exclusivity for the ZO6....

musclecar6

To me, this is pretty simple. Unless GM doesn't have time to complete testing for both the C7 and the Z06, it seems highly likely that they will put the A8 in the 2015 C7. It also behooves GM to not announce the A8 will be going into the 2015, if that is their plan, until the April bash when they typically announce and display changes to the forthcoming new model year. They still have 2014's to sell, which will have the obsolete A6, if the A8 is introduced in 2015.

JerriVette

With the new 2015 Chevrolet Corvette Z06 that was introduced this past week at the Detroit Auto Show, GM raises the threat level to the bragging rights of virtually every other supercar in the world.
And while performance numbers are still months away, there were plenty of interesting details released with GM’s Z06 announcement—like an all-new ‘LT4’ engine, as well as a new, GM-designed eight-speed automatic transmission designed for exactly this application.

That new ‘8L90’ transmission, designed completely within GM, by a dedicated team, is a traditional hydraulic automatic—solenoids, valves, planetary gearsets and all—but GM says that it provides the super-quick shifts of dual-clutch boxes, yet with more smoothness.

The eight-speed automatic is actually quicker-shifting than the PDK gearbox in the Porsche 911, GM officials say; and that’s a transmission that engineers benchmarked for the project.



“Almost a custom transmission”

Corvette chief engineer Tadge Juechter pointed to some tough packaging challenges. There wasn't any existing dual-clutch gearbox that could take the torque of the engine and would fit in the space permitted.

“It's engineered by GM, internally, and many of the parameters were focused on this car,” said Tadge Juechter, at a pre-show event. “So it's almost a custom transmission.”

“We wanted a transmission that provided everyday drivability and compatibility with cylinder deactivation,” Juechter explained, while they also wanted the speed of a DCT. “When you run in four-cylinder mode, a torque converter is really your friend” in everyday cruising conditions, he said.

The transmission will be used in other applications, Juechter confirmed, but many of the attributes of it were driven by the parameters demanded of the Z06 project.

Also of note is that the transmission offers up to a five-percent fuel economy gain over a six-speed automatic used in the same application

Two-port ‘smart pump’ design a key to being lean and quick



2015 Chevrolet Corvette Z06 - GM 8L90 8-Speed Automatic Transmission
That’s due to a host of engineering changes and analysis of the transmission from scratch, looking at the most efficient path for torque flow. But when we pressed the engineer overseeing the project for the single most important design attribute, he pointed to the ‘smart pump’ setup, in which GM incorporated a binary operation with two inlet discharge ports.
To put it as simply as possible, this clever hydraulic pump system works a bit like the cylinder deactivation the Corvette already has. Under acceleration and aggressive driving, the transmission uses both ports and provides more flow to the clutch packs, to speed up shifts. And then at cruising speed it relaxes to a single port, which reduces drag.




One other key to help minimize drag and mechanical/friction losses for this transmission, which has five clutches and four planetary gearsets, is that only two clutches in any single gear are open at one time. That plays a role in speeding up downshifts, too.
The unit, overall, is the same physical size as the existing six-speed, with the casing and input shaft area designed to be compatible with the C7 Corvette’s ‘torque tube’ that runs down the center of the car and is essentially part of its structure. And thanks to aluminum and magnesium construction it’s eight pounds lighter than the outgoing six-speed. Yet it was designed to allow up to 1000 Nm (738 pound-feet) of input torque—which could suggest, perhaps, that GM could eventually sell them to niche ultraluxury makers with torquey turbocharged V-8s and V-12s.



Tall overdrive ratios? Check.

The new transmission offers deep overdrive ratios for seventh and eighth gears (0.86 and 0.65), while sixth gear is a direct drive. The new setup also allowed them to drop the base axle down to 2.41, from 2.73 (the latter will still be available as an option).

GM is still making decisions about shift pattern, shift points, and the the map for cylinder deactivation, officials said, so any announcement on fuel efficiency will be months away. And its operation in the Z06 would of course be tailored by the Corvette’s mode selector.

The transmission, as it was engineered, would to be able to go into any of GM's rear-wheel drive applications. We take that as a strong hint that this transmission may be headed into the C7 as a rare mid-cycle improvement.

While we’re curious to see where this transmission lands next, we’re eagerly awaiting performance and fuel economy numbers for the Z06. By offering a choice between a seven-speed manual or eight-speed automatic, the 2015 Chevrolet Corvette Z06 stands out among 600-hp-plus vehicles. Based on the suggestions of those involved in the project, we’re also expecting the Z06 to be one of the most fuel-efficient supercars on the planet.

Source Motor Authority

JerriVette

Optional rear axle ratio usually translates to non z51 and z51 models both as standard stingrays and not z06.

What year I can't say but the rush to increase fuel economy leads me to believe 2015 model year although the z06 won't hit the showrooms until December 2014 or January 2015....

It could be a delay of a year for the more traditional deliveries of standard stingrays to get the A8.

Will be April I'd guess well know for sure.

Both great transmissions but I'm digging the hype on the new A8 so at this point I'd wait to hear....

NSC5

I am sure there will be several 8L series transmissions with different torque ratings to be used across the GM line and there will probably be an 8L80 or similar nomenclature rolled out for the LT-1 and some of the pickup applications along with lower rated units for most of the RWD Cadillac line. I expect 2016 to be the year when the LT-1 C7 gets its 8 speed variant.

Dr. ice

Agree. Google C7 8 speed automatic. As stetted in The SAE white papers the 2015 c7 will have the A8.

B-Vette

I'm on the fence between the auto and manual transmission currently being offered on the new C7 but if A8 is going to be a reality, I'll definitely wait out my purchase.

green2000

They might not have initial production capacity to offer the A8 across the line so starting with the Z06 could be a wise move.

SCM_Crash

Well, that's true. I guess we'll find out. Though, they didn't have such a hard time offering CF dash and roofs even though they didn't have the volume in parts. LOL

SCM_Crash

You realize that they did only produce one. The LT4 is simply a supercharged LT1.

beepster

Hope it will be an A6. To me the A8 would be overkill just like the 7 speed manual trans. The 8 spd autos I've driven are a PITA with the constant downshifting. In traffic, these transmissions are constantly "hunting" for the right gear causing the vehicle to surge. I cannot even imagine the horror of coupling an 8 spd auto w/ the 8/4 feature...

SCM_Crash

Have you been driving the 7-speed and talking from experience? Or are you just assuming it's overkill?

I've been driving the 7-speed for the last 4 months and I've really enjoyed it. It's definitely not over kill. It's that extra gear I always wished I had in my Z06.