Why manual trans. gets 7th gear, but not auto???
 

Everyone knows by now that the Stingray's manual trans. will receive a 7th gear, and the A6 will remain @ 6 for this full model change. In the March 2013 issue of Car and Driver Tadge Juechter (Corvette Chief engineer) was asked whether a dual-clutch auto was considered on pages 38-40.

His response edited for brevity:
The number of speeds isn't everything. We introduced the C6 with four-speed automatic, introduced 6 speed in the second year and had a h3ll of a time beating the four speed in both fuel economy & performance. We operate at high torque / high efficiency across a broad RPM range so we don't need more gears.

If that is the case then why add a 7th gear to the MT??? Maybe an engine / trans guy can chime in here. I frequently skip 5th gear in my cars with 6 speeds. I'm failing to see the benefit of 7 gears in this application. Maybe cool with flappy paddles - more accurately a DCT, or single clutch auto - but that seems like a lot of shifting (or skip shifting) with the MT.

Using more gears in smaller displacement / high revving engines to keep the engine in a narrower torque curve is common among Japanese, Italian, etc. automakers. But the logic for Stingray seems odd.

Wanna chime in here Mr. Juechter???

...and isn't the future (MY 2016 ?) C7 automatic supposed to have 8 speeds ?

I believe Aisin 8 speed rumors have been prevalent prior to the debut. Even if the rumors are correct I'm failing to understand the Chief's logic with MT7 vs. A6... or A8 for that matter. What ROI (return on investment) do they receive for this change? Maybe an engineering accountant can chime in now... :leaving:

Mr. Juechter, Moss, Bailey.... I'm not trying to be picky (although it certainly seems like it). I'm just trying to understand, from an engineering standpoint, the operation of one system compared to another. Again, I frequently skip shift on my 6 speeds, so I'm not sure where a 7th becomes useful? Does it have something to do with cylinder deactivation?

Again, I'm not knocking the transmissions - just trying to gain some understanding.

It's my understanding that 1st-6th gears are pretty close to the C6 gears, and 7th is another, slightly taller, overdrive. It's meant strictly for highway cruising to eek out just a touch more MPG.

Sooner or later they will have to upgrade the auto to 7 or 8 gears. He also said the they did not find a dual clutch that could handle the C7 torque, but i don't buy that because the 911 Turbo and the Ferrari Berniletta both have more torque the C7 and they used the dual clutch trans.

I think it comes down to they could quickly & cheaply upgrade to a 7 speed manual vs the Auto in which will take a lot more engineering to get it done.

Do they have to up the number of gears in the A6??? If there's little or no performance benefit then why upgrade? Maybe continual refinement is ok... It seems to work for the 911.

I agree that there are transmissions that can handle the torque, but they continue to say indicate fitment may be an issue. Maybe the Vette's rear end is more cramped than some others. Please correct me if I'm wrong but I believe the clutch is at the rear of the car with the trans. Maybe other auto makes with front engine/rear transmissions have the clutch up front? That one I'm definitely clueless about.

As an engineer I'm skeptical of "change for the sake of change." Maybe the 7th gear let them squeeke past gas guzzler tax? What's the real reason for the switch?!

I'm anxious to drive one and see how it feels to row through 7 speeds... Or maybe ship shift two lol.

I believe that the gears in the 7 speed are geared different than the currant 6 speed, in the C6 5th gear is where you reach top speed and 6th is overdrive. In the C7, 4th gear is 1 to 1 and you will reach top speed there, 5,6,7 are overdrives. So now you are driving a techie 4 speed, your skip shift here will more than not be 2nd to 4th, and I bet it comes set up that way, also guessing that when in sport or track mode that is killed

The C6 is also 1-1 in 4th gear making 5th and 6th overdrives. Top speed in the C7 should be in either 5th or 6th depending on final ratio numbers.

Some of these 'messages to Tadge' would be far more effective as actual messages YOU SEND TO TADGE vs putting it here on CF thinking he comes here to get his email.:yesnod:

Also, I'm sure that 'as an engineer' you know that everything you do in the course of your daily work doesn't require you to explain it to the consumer on a public forum. BTW, engineers are often called upon to fulfill 'change for the sake of change' at the whim of marketing/upper management.:D

I'm sure part of it is economics. Does it make economic sense to force faster development of a 7 spd auto that you don't really need but that the marketing folks are screaming for? They already have the 7 spd manual and are working with Ford on 10 spd (essentially like a CVT, which would be very interesting) autos for performance vehicles.
http://www.autoblog.com/2012/10/01/f...eed-gearboxes/

Right now, I think its all about trying to eek out every little bit of fuel economy. By trying ot keep rpm's lower in every gear for "normal driving" it helps with the enrgy modeling and overall ratings. By doing this, it helps smooth out the overall corporate mpg rating, which is necessary to meet federal standards? most of wont drive our vettes in this manner though. sometimes its about meeting some performance mandate, other times simply marketing right? they could probably build a two speed powerglide trans and call it a day, but it wouldnt do everything we want it to do for the car.

I just bought a new 13 pickup for the business, and it has a six speed auto that keeps the motor pulling less than 1200 rpm through the range, unless you mash the throttle. it does very well on fuel economy as compared to my 2011 platinum with a four speed.

I think Tadge stated there was nothing available that would fit the C7, basically no direct bolt in transmission. Therefore, they are developing a in house 8 speed Hydra-Matic. In his statement he was evasive on the precise date or even if it was a 8 speed auto, but that could have been for the sake of selling the A6 before the A8 comes out in a year or two. Major manufacturers are going with 8 speed autos, Dodge has had a 8 speed available and has stated they are looking at a 10 to 12 speed for the future. :cheers:

He probably won't because he doesn't surf Corvette Forum. Neither do many of his minions.

The days of manual transmissions being significantly more fuel-efficient than automatics is basically over. With the computers at play, an automatic-equipped car and bumble down the road and hit an acceptable (whatever that number is) FE number. Manuals are trickier from an engineering perspective because of that squishy thing (driver) making the gear decisions.

That may be part of it.

Further, GM's pretty keen on using their own internally developed automatic tranmissions. For the Corvette, they don't even bother making a manual; they leave that up to the folks at TREMEC. It's quite possible that GM has a 7-speed auto in the works, and TREMEC was able to get the 7-speed manual out faster. That one's purely a guess though.

jas

Well C7 is a new car no surprise that there are not many bolt-on automatics :) This just says that automatic is more of a afterthought and C7 was not developed high performance automatic in mind.(And of course they promote now hell out of the M7)

Need more coffee ...........:leaving:

Why doesn't the auto get a 7 or 8 speed? B/c this is GM. They are always behind. There is a reason they are in the red.

GM was profitable in 2012 to the tune of approximately $5 billion.

http://www.forbes.com/sites/joannmul...ut-to-explode/

http://www.usatoday.com/story/money/...arter/1918293/

Net?

The A6 already has a great gear ratio spread than the M6. It goes from 4.02 to .67 with a 2.56 rear gear so 10.29 to 1.72 final drive. The 6 speed goes from 2.66 to .5 or 2.97 to .57 with a read gear of 3.42 so 9.1 to 1.71 or 10.16 to 1.95 final ratios. So the spread for the A6 is 6 and the spread for the M6 is 5.2 or 5.3. The M7 spread is 6.33 or 6.19 and final drive ratios are 9.1 to 1.44 or 10.16 to 1.64. This brings it more in line with the A6. The spread is slighty smaller for the A6 but, not really because the torque convertor acts as a gear multiplier, so the effective spread is actually higher.

So the Manual got more gears because fuel milage was improved more on it.

I read the same - nothing existing fits the architecture of the C7

They made a new Corvette. Make a new trans that works with it. Other makers have no problems offering 8 speed autos. Get with it, GM. Idiots.

So what 8 spd auto that anyone is making are you driving now? How's that working for you?:D

I seem to remember one of the car magazines discussing this. C7 engineers said there was no dual-disc paddle-shift transmission that could handle the 450 pounds of torque. The magazine writer said the Porsche PDK, designed jointly with ZF, could handle the torque but GM was not going to license parts from Porsche for the Corvette. Interestingly the Porsche 7 speed manual and Porsche PDK are almost the same transmission, many parts are the same. ZF designed it this way from the beginning to save production cost.

I think a new automatic will be introduced for a few reasons. Better EPA numbers, marketing, better performance via better hardware and advanced programing. Performance is my priority.

Automatic transmission computers are integrated into the advanced electronics in a modern car. This enables engineers to program shift patterns for economy and superior performance. The computer can sense what a car is doing via throttle opening, yaw sensors, traction control, abs, electronic differential, steering wheel angle sensors, brake pedal sensors, etc. Up-shifts, down-shifts, gear holding all are optimized. Though designs are different, auto-manual transmissions like the Porsche PDK and Mercedes AMG Speed-Shift MCT have advanced programing where the computer performs like a pro racer. The computer knows when to shift up / down, hold gears in turns, out of turns, under braking, etc. Shifts are faster.

We are not getting a PDK style, maybe one like the Benz? AMG Speed-Shift MCT is a traditional automatic design where the torque converter is replaced. This is a quote from Wikipedia: "Instead of a torque converter, it uses a compact wet startup clutch to launch the car from a stop, and also supports computer-controlled double de-clutching."

I'd be happy if GM has something that performs as well as the AMG Speed-Shift MCT. This is the transmission GM needs to benchmark if there is not a dual-disc option.

Maybe he drives a Chrysler. They offer cars with 8 speed automatic transmissions and you can buy a 300 for only $30,000.

But back to GM, from a GM press release...

"With Ohio Gov. John Kasich, U.S. Rep. Marcy Kaptur, D-Toledo, and Toledo Mayor Michael Bell in the audience, Akerson said GM will invest $204 million to retain about 250 jobs for an all-new, advanced 8-speed automatic transmission for future vehicles that offer customers improved fuel economy and outstanding performance."

If ever there was an appropriate screen name - you've got it.

Maybe...he could answer for himself.:D

Yeah, GM is working on a variety of auto trannys including collaborating 9 (front wheel drive) and 10 (hi-po) spds with Ford.

And that's a reply from a posting whore, that has made more posts in his 1 year of CF membership then I have in nearly 14 years.

If you posted based on direct question made to you, then your post count would be around a dozen.

Oh, I see...you decide to answer for someone else with an idiotic answer because I'm a post whore. :rofl::rofl::rofl:

I don't answer questions put to other people.

The DCT in the current M3 is a blast to drive!!! That was the most enjoyable part of driving that M3, besides getting pulled over by chicks that wanted to talk. A DCT in the C7 would be insane!

Yes, Net. Not only that, but 2012 was the third consecutive year that GM has been profitable.

"General Motors reported today a third consecutive year of profitability in 2012, with net earnings of $4.9 billion"

Was that before or after they paid back the taxpayer 100% of the money stole from them and handed over to GM.

Agreed! Puulease Tadge!! This is GM, not Yugo.
Make it handle the ouput and make it fit! You can do it Buddy.

Seems like very bad investment. 204M for a transmission. They could just send the C7 to ZF and Aisin and they have figured it out and sent the car back with a price tag for the transmission(or license). Of course if they got "free" government loan I understand the loose hand on the wallet.

The transmissions will used across the GM line, not just the Corvette. No different from the A4 in the C5 and the A6 in the C6. maybe 7,000 a year used in the C7 but 500,000+ a year in RWD cars and pickup trucks and RWD SUV's. Of course another version of the 8 speed will be used for FWD vehicles.

A C7 with a Dual Clutch tranny as quick as the one in the Ferrari 458 would be incredible.

Before I ordered my 05 C6 there were rumors of a 6 speed auto being released for 2006. I was assured by my dealer (a forum member) that the A6 wouldn't be out for 2 or 3 years and I should buy the 2005 so I bought one.
Burned once, I'll wait for a year or so this time and see when the new trans shows up. There's NO WAY GM can compete on the world market with an old school A6, no matter what the PR about torque numbers are. I guess MB and RR motors don't make big torque numbers so they need the 8 speeds? Come on GM, get real.

60ms shifts = sweetness.
It's a getrag, so if it didn't cost 20% of what it costs GM to build the entire corvette they would probably use it.

One of the engineers did say that they have gotten the shifts of the A6 down to 200ms. Thats ferrari 575m and f430 speed (and alot cheaper).

Jag F-Type with 495 HP and 460 lbs-ft of torque with an 8 speed auto.

Not sure but did Tadge actually say 450, or was the statement a generic "would not handle the torque"? Cause any C7 tranny is gonna have to handle alot more torque than 450 in the hipo models.
Maybe they are thinking 600-800lb/ft not 450.

I prefer manuals but since I'll use the C7 as a GT I'm delighted it has 7 speeds.

So what? About 3600 lbs. Base is a V6 (265 HP) and starts at $69k. V8 F-type V8S starts at $92k. Oh, and it's a Jag with a mouth like a catfish.:ack:

This is an easy one. The first year of the C6, the old 4 spd auto was available. Rumor about a 6 spd auto was out there, but naturally GM wouldn't confirm or deny it. Duh, gee, ya think this could be happening all over again. If an 8 speed auto is planned for next year or the year after, ya think they're gonna tell us ? Would you if GM was your business & you're trying to sell C7's with an old school A6 ?

We have no way of knowing what horsepower and torque that Jag is planning in the future. As of right now, their 8 speed transmission will handle the horsepower and torque their current engines are delivering.

And you do not know what horsepower and torque of the engines that GM is planning for the C7 in the future or what transmissions they will use.

Currently GM has a transmission that will handle the 580 HP ZL, so it stands to reason they will also have a 8 speed auto that will handle 580 Hp.

And it also stands to reason, that if Jag offers a 580 HP engine, that they to, will have a transmission capable of handling it.

The 8 speed automatic for both the trucks and the corvette are delayed because of bankruptcy.

The 6 speed automatic is probably holding back 2 mpg to the a8.

I believe the performance difference will be a tenth of a second