Carvin

Is there a way to find out how common the A8 problems are?
I was figuring on museum delivery some day but am getting concerned.

\Boost Monkey/

You haven't even ordered a C7 yet?

The revised transmission is already being installed since October of last year....you are fine, don't be concerned.

Honestly, I'm not and I have the unrevised version. The issue is not an epidemic, just a possibility and I dare say a uncommon one.

Doug Z06

10/15 for me as well. Would suck to have just missed the new tranny by a week. There must be a way to confirm if our cars have the old or new tranny. Although, I have my doubts if this (new tranny) is fact or forum chatter.

kp

There is no facts except a changed part number, many get changed all the time for various reasons. Until someone shows the difference between the two with before/after dates in a factory service manual its all a guess.

Plus sometimes because something is 'changed' it doesnt necessarily mean its a good thing, they may have replaced some expensive magnesium parts with aluminum or sourced some different internal parts from China.

They made 23,232 A8 Corvettes in 2015 alone, I'm sure many of those are just fine.

IMO the OP has two problems, a transmission issue and a dealer issue. Both should probably be replaced if its that bad..

Maxie2U

I may at some point call my dealer to see if they know anything about an "updated" transmission. They are a good bunch of people and very knowledge.

Black&White

Do you think if the question was put forth in the "ask Tadge" section we would get an honest answer? Or maybe at the NCM Bash in April??











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\Boost Monkey/

Yes, you should post it up and i would vote for it.

There is no reason he would not answer the question directly, and I don't see how a revision already in production would be proprietary information.

I, personally, would like to know the exact changes. Like that other guy posted, we don't know what exactly changed and this whole revision could be a moot point.

Len44

^^^^

I'd vote for it too.

Doug Z06

Gets my vote. Seems about as much of a discussed and controversial topic as any. Although, I don't see the answer containing a statement to the effect, "the transmission was updated to correct a known problem..." Too much liability and exposure acknowledging a known defect. Just look at Tadge's catch can answer... and then the '16 Camaro comes with a catch can.

HC-C7

How bad is the shudder . Something noticeble like you just hit a big pot hole or just a little shake now and then which would be normal . I have the A8 and the only thing i am annoyed by is the wheel hop when turning at slow speeds. The torque converter has a rubber disk which is a flex disk . These develop cracks hard to see and they can cause issues that will effect driveability . They usually last longer then 12k depending on how you drive or where you drive as in weather . Cold can crack anything that heats up very quickly.

Red C8 of Jax

Maybe there is a way you can find out your part number based on your vin? If it is the new one, you are in the clear.

Ernest_T

I think I may be experience this issue too. The last time I drove down the highway at a steady speed I felt the shudder. The car was going into and out V4 mode so I thought that may have been it although the shudder was harsher than what I normally feel when it goes between V4 and V8. The car is a 2015 with a little over 9000 miles on it. I'll pay more attention next time I drive it.

Red C8 of Jax

Set your cruise control and your car will stay in V4 and you should notice the shudder in your steering wheel. It will shudder for about 2 seconds, stop for several seconds and shudder again. It will continue to do this over and over again. Look at your RPM's and they will move up and down a little every time you feel the shudder. My transmission is being replaced because of this problem.

Mr. Jones

I have an early 2016 A8 no issue.
But as far confirming an issue trans or AFM
If you feel a shutter put the car/transmission in manual at a steady highway speed.
No V4 will activate-is there shutter now?
If not it's not a trans issue.

AdventurePoser

I feel very badly for those who are going through tranny replacement issues and dealer issues as well.

I equate this to the controversial BMW motorcycle threads about failed final drives. If you read the forums, your motorcycle's final drive will fail, because it is an endemic issue that BMW cannot/will not solve, or admit exists...

Yet I wonder how many final drives really do fail? I started riding in 1999. Since then I've ridden nearly 300K (86K on one bike since 2011) Yes, we love to ride. And yet I've never had a problem, nor has anyone else in my riding community. In fact, I checked with a large BMW shop in So Cal who told me they've replace two final drives in the past five years, and sold thousands of bikes...

My point is, the bridge that falls makes more noise than the one that stands. Be aware a problem could exist, but MANY thousands of 2015 Corvettes are just fine and will continue to run well. The internet magnifies every problem.

Good luck and do more driving with less worrying about what will probably never happen.

kp

Exactly, with 23,000 cars out there can you imagine if someone from GM said they will all need the trans replaced at 12K. Thats a lot of $$ at 2K+ a pop.

The A8 trucks are having some similar issues, all seem to go back to the torque converter. Seems they wont replace the converter without replacing the trans..

I have driven a '15 and two '16s on the highway, they all had what felt like running over a bump or a rough shift when the converter locks/unlocks. I havent felt one shudder but its possible if the TCC is not right it can shudder when locking/unlocking. Especially in V4.

I'm not defending GM, too many people complaining for it to be made up. Time will tell when these cars start getting more miles on them.

Maxie2U

I recently watched a you tube video produced by MotoManTV it was a behind the screens design of the C7. Most of video was a discussion with Tadge about the C7 design elements. In one segment, Tadge discussed the reason why they decided to go with a steel torque tube instead of an aluminum TT.

Tadge stated a steel torque tube was required because of the vibration produced when the C7 switches from 8 cylinder mode to four cylinder mode and visa versa.

IMO, even with a steel torque the transition from 8 to 4 mode can still result in severe vibration in some C7s. This is why I installed an AFM disabler.

DAFFYDRUNK

I'd be shocked if this was addressed in Ask Tadge. Didn't read the catch can response but I'm sure it was bull$h|t. That dude gets paid a lot of money to lie. I guess I'd lie to thousands too if I could make that kinda bank.

kp

The converter will still lock/unlock when not in V4, you can see the RPM go up or down and feel it when in V8.

Thats why the M7 cars dont go into V4 unless you put it in ECO, they dont have the dampening effect of a fluid filled torque converter. The torque converter clutch in these is used a lot, for both mileage, efficiency and to probably help manage trans temps. Doesnt take much, whether mechanical or bad programming, to mess things up and feel it.

The whole trans was new in 2015, I was a little surprised that people who not buy a 'first year' 2014 Corvette lined up to buy a 'first year' auto transmission - one of the most complex mechanical parts of the car. My wife's Jeep has gone through two 'new' 9 speed autos in under 10,000 miles, and hers is far from the only one. Yet the new Cherokee is still one of the strongest sellers for Jeep - go figure.

But then again the 'classic' A6 in my '15 Silverado is the worst shifting auto trans I have ever owned. The A6 in my old '14 was far from perfect as well but it didnt have the occasional jolts and the busyness of the A8.

\Boost Monkey/

Yes, and also a torque converter (transmission) was what was required because of the stupid AFM. The TC helps to dissipate much of that vibration that is caused from the transition from V8 to V4 and back.

I'm no expert and still learning, myself, but i believe the TC slip is computer controlled to "micro" slip when the AFM transition is made in order to absorb some of the vibrations. A DCT is not able to do this, thus the requirement for a classic torque converter auto.

This is a great transmission, all issues aside. It shifts in auto faster than a dual clutch, even though technically speaking there are alot of similarities between a DCT and this 8L90 that it shifting as fast, or faster, shouldn't be a surprise to anyone.