davepl

Yup, though for the volume the ZO6 A8 sells, how much difference AFM on that limited production actually makes for their CAFE average, who knows... can't be much.

Doug Z06

What timing on this thread. I just picked up my 2017 Z06 on Thursday from the dealer. New transmission. 4500 miles. I don't think it makes a difference what car or what year the car, transmission is garbage.

I had a 2016 Z51 that had a bad transmission too.

What are the odds - 2 for 2 go bad. Still love the car and won't buy anything else... until the mid-engine comes out!

2fastnow

I read somewhere that the v4 v8 thing was fixed by a better tensioner. Not hear but some truck threads out there and maybe some Camaro threads out there. If you don't remember the question you asked Google it's futile.

C7/Z06 Man

GM should run a campaign to remove the V4/V8 AFM mode.

NSC5

There was a noise issue created by the serpentine belt tensioner in V4 mode and there was a separate issue with the LT4 supercharger belt creating noise but the major issue I believe people are focused upon mostly in the A8 threads is the shudder that is from V4 induced torque converter failure.

glass slipper

As stated above, you'll occasionally find mistakes on the GMAuthority website because non-engineers take info from engineers to form a press release/article and then try to add a little spin to it. One press release stated the pistons in the LS7 were forged...it took a long time to dispel that one.

The 8L90 has 5 clutches to apply/release and no sprag clutches (unlike the 6L80 which has one sprag clutch). If you want to find more info about the 8L90, you can check here:

http://www.atra.com/Webinars/GM/8L90_Introduction.pdf

I buy most of my technical books from this website to analyze the hydraulic circuits and get a general feel for what the engineers were thinking relative to certain design elements. My main background is hydraulics so I'm always interested in new developments. I'm sure they still have webinars you can sign up for if you really want to dive into a transmission and how it works.

Torch Red Z06

Agree

itsonlyairandfuel

If you want a motor with one less set of problems. It has been a problem since day 1, on all cars and trucks. Salesman that are car guys, will try to steer you away from AFM. jmho. Ron B.

pkincy

I don't know if it will help, but I only run my A8 in M mode. And I run the A8 in my ATS in M mode about half the time. Just more fun as well as a precaution I suppose.

davepl

GM retained AFM on the A8Z even though it didn't pass gas guzzler in order to maintain their CAFE averages, that's all. Or laziness, but I assume CAFE.

2fastnow

I know why. Someone at GM found some old blue prints on cylinder disarming technology. It's the curse of the 8-6-4 Cadillac motor of the 80's.
I'm afraid these cars will end up in the auto history books along side the Ford Edsel and most Fiats.

BPSCZ06

The A8's are trash. Faulty converters, gm dealers replace them in Yukons and trucks left and right. GM knows it too. Thats why the 10 speed is coming to replace it. My 16 CTS-V needs a converter and V4 mode has been shut off. low rpm crusing the car has almost a misfire sensation from the TC.

NSC5

For years GM has also use their C3 technology to try to reduce low speed powertrain vibration and harshness. (C3 or capacity coupled clutch is one of the names they have used for a torque converter clutch that is designed for frequent lock/unlock cycling). This is what led to a series of material changes/upgrades to allow the clutch to withstand this sort of service duty cycle because they have gone through a number of sequences of torque converter clutch issues but just not to the level of what they unleashed with the 8L90/8L45 and its very aggressive clutch modulation. Trying to implement this flawed strategy is a perfect example of the British expression, "too clever by half" and instead of facing up to its failures the corporation has doubled down by continuing to throw new parts into the mix. Just disable the damned clutch modulation; I expect 99 out of 100 users would rather have a little vibration at times instead of the very real problems and failures caused by this terribly flawed implementation.

Apparently there was a suggestion contest at GM as to how can we make V4 mode worse and the winner was the person who came up with a way to greatly increase the damage done via V4 mode. Or for the conspiracy theorists this is the GM method of pushing electric powertrains-make the internal combustion powertrain annoying enough and people will run from it

Take a look at this link for some more info on the long history of converter clutch issues now culminating in the 8L90/AFM debacle: https://www.transtar1.com/TranstarIn...TLT-TC-035.pdf

2fastnow

Your right, GM is wrong but once admitted, it can almost destroy their bottom line with scores of honest/dis people wanting a new A8 across model years and brands. They are sitting back replacing what they can till a new better one comes along so the world can forget.

Big Lebowski

I don't know about all that...mine was dropped and torn apart in the first 6 months.

davepl

You're seriously comparing the Z06 to the Edsel? I'd love to hear your reasons why.

LuckyC7Z06

It's more than the converters. My 2015 Denali has the same A8 as the Stingray Corvette basically same engine. I had problems with it 2 months ago and they just pulled it and replaced with "new" A8. I was told all early 2014-2015 models A8's that have problems are just being replaced by a 2016+ model. The Zo6's didn't have that issue as they were built more robust because of the added HP. They dealerships aren't even messing with them they just diagnose there is a problem and pull it. I lived with mine acting funny for a year but like I was going to give it to my dad for his birthday I took it in and they replaced tranny had it back on the road in 3days total and drove off the lot with a new Denali HD!

rogue3standingby

Including myself, I know 3 people in real life (outside of forums) that have C7's. The last remaining one was admitted to the dealer today with a bad torque converter, so that makes all 3 of us now.

My transmission has been removed from the car 3 times now. Also had the common belt tensioner failure, not to mention still fighting with the dealer over very hard/missed shifts and that thing where it feels like you get rear-ended switching from Park to Drive.

There's just no way around it, there's big problems with these cars. The problem is, so many Corvette owners put a measly 1,000 miles per year on their car. I guarantee these cars will go down in history as a complete cluster.

BPSCZ06

Its not the cars, its the transmission period. No matter what car its in, its failing.

2fastnow

I seriously can't convey my witty charm/humor on any forum.

I was over dramatizing the situation.