Bill Dearborn

I agree with you to a certain point. Up until recently automatic transmissions had a fluid connection (torque converter) between the to engine and the actual transmission thus were indirect drive transmissions. All manual transmissions were direct drive through a clutch. In the last 30 years or so the torque converter clutch was added so these indirect drive transmissions became changed to direct drive once the vehicle was on the highway and in the upper gears. The DCT isn't and has never been an indirect drive transmission. It is a direct drive transmission with all of the good features of a direct drive transmission and a lot less of the bad features. The biggest bad feature it is missing is the necessity of using the clutch at times when clutch use is a huge PIA. It is a transmission that gives the guys who want to shift on their own all they want and the guys who want to let the car shift itself all they want. Other than potential technical/reliability/usage issues that I may not know about I don't see they would have any other transmission in the car. From a manufacturer stand point it eliminates a lot of maintenance and support issues, it eliminates the cost of maintaining two different part numbers in engineering, reduces inventory costs, reduces support costs by eliminating one set of special tools, etc, etc, etc. These are all good things on a low volume car.

Bill

johnglenntwo

There new auto is supposed to be as fast as an auto sequential on up shifts. A bunch of fast gears is a really efficient substitute for power. Hence, the semi-trailer trucks with all those gears!

Caddylac10

Just sayin...

For those wanting additional confirmation, today Motor Trend has just repeated what I said originally and knew almost a year ago.

I wouldn't say something as notable as my original post without being confident about my source.

Can things change and could myself and MT be wrong? Sure, but I have no problem being wrong by trying to bring a good peice of information to the forum after careful consideration and some much more reliable source verification than you think.

Read more...

We Hear: 2014 Corvette, New Cadillacs to Use Aisin Eight-Speed Auto Before GM’s 8A Arrives

JerriVette

I would have preferred a DCT transmission as I want this technology in my next new sports car purchase. I have heard rumors that GM has been able with new technology and programing so there is supposedly no reason to want a DCT transmission.

I'm willing to wait and test drive one to at least give them the benefit of the doubt..

If GM buys a Toyota 8 speed for one year....that would probably be a model year I'd definitely pass on unless it got rave media reviews beyond DCT tech and got to test drive it as well

SCM_Crash

Honesty, I'm still at a loss as to what makes the DCT so much better than a standard auto with today's technology.

I get that there's potentially less power loss through a DCT, but the truth is that with today's converter technology the energy loss isn't nearly as much as it used to be with standard torque converters.

And with the 6+ speed transmissions, they have multiple sets of gears like a DCT, they prepare for the next shift just like a DCT does. The difference is that the standard autos use clutch packs and the DCT uses two solenoid driven clutches. In theory, their performance should be equal as far as shift speed if the standard auto is programmed right. But remember that good programming is a must on both transmissions. In addition, a standard automatic doesn't require the engine to cut fuel and/or spark before the shift, while the DCT does.

Just thought I'd throw that out there. I'm not saying that one is better than the other. I'm simply wondering why there's such a fuss about the drive engagement style of an automatic transmission.

Maybe I'm just not understanding something... (I admit I'm not expert here.)

NSC5

If the one year deal is true I wouldn't care to own a Corvette with this unique configuration. Warranty service would be a nightmare since there will never be any in-house expertise developed and any parts unique to this configuration could be a post warranty issue.

millpond

If I go with an early C7 it would have to be the manual trans.

jimmyb

So, Glass slipper....

You smacked around Caddylac10 in 4 different posts (to the point of being rude) and as it turns out, HE'S SPOT ON (about the Aisin 8 speed) AND YOU'RE NOT.

Next time, you might want to....never mind.

Jimmy

brentil

How about we talk about some technical details in an informative manor about the topic instead of this total troll behavior. This is the type of behavior I expect to see on a tuner forum, not a Corvette forum... I went from being the admin of the Solsticeforum/Skyroadster forum to a lurker here because of threads like this.

As several sources are quoting now the Aisin 8sp TL-80SN which is also in the Lexus IS F is the most likely candidate for the C7. Collecting info from the Aisin's resource page and Lexus IS F documentation we find the following details. Some have mentioned a couple of these but I wanted to collect them together.

• 5% faster acceleration (compared to "conventional" 6sp)
• 7% lower fuel efficiency (compared to "conventional" 6sp)
• 2 kg (~4.5 lbs) reduction in weight (compared to Aisin 6sp)
• Virtually instant manual upshifts (as quick as 0.1 seconds)
• Blips the throttle on downshifts
• Torque converter lock-up clutch for gears 2─8

It's late but I wanted to also grab the current C6 6AT information to compare some data between the two designs. This is obviously not a DTC but the values and tech make it much more inline with them. The upshift speed and throttle blips are common on most DTC systems now and the performance converter lock-up on gears 2-8 provide "clutch" like performance by eliminating nearly all torque converter slippage.

Racer X

People forget that the torque convertor has advantages. It has smoother transition from idle in normal driving conditions. It is a torque multiplier (about 2 to 1 IIRC). This is part of the reason they are so successful in drag racing. As mention once they go into lock-up the torque convertor is a non-issue except rotating mass.

Kappa

The transmission in the IS-F is pretty ridiculous. Would love to see it in the C7. It's the quickest shifting automatic out there(I don't count DCTs as autos and the IS-F box outperforms many of those too).

brentil

Information like this also leads me to believe that the GM built one should be on par if not better than this (I at least hope so). Otherwise what's the point of spending millions on making your own when the Aisin does a very solid job.

Where I think this Aisin will shine/fail in the C7 will come down to GM's software for the transmission and how they fine tune it to the new car. They have some unique challenges to overcome like rear mounted transmission and now the Active Fuel Management for the new LT1.

JoesC5

Could be that GM would like the profits from manufacturing/selling a transmission, that would be going to an outside supplier, stay at home. Remember that we are talking about a transmission that will be used in several different lines, not just the low volume Corvette.

brentil

That is true, it'll start in the Corvette/Cadillac and eventually move down to Buick & Chevy.