Originally Posted by MidLife+

My 2 cents.... I can use manual mode on the A8 and still have the shudder. Manual mode does not allow the AFM to function. my 2016 Z06 has had the fluid flush and torque converter replaced. I still have the shudder and erratic/sloppy up and down shift at times. Taking it back to the shop today to determine what their next step is.

Originally Posted by MidLife+

Today's Report: They will be replacing the transmission valve body. Back ordered from the factory so it will be 4 to 6 weeks to get one.

Originally Posted by stevesrubyred93

Here is another update. I picked the car up on Saturday. they did the flush and they told me to drive it 500 miles. He said that if I still have problems, they would replace the torque converter. I don't have to drive it 500 miles it's still shuddering when I accelerate. It does shift smother, but still have a shudder vibration. I have ordered a Range unit and it is supposed to arrive Thursday.I'll try it, but I think the converter will need to be replaced.This Sucks.

Originally Posted by stevesrubyred93

Here is today's update. Dropped of my car a few hours ago and the service manager told me that it did sound like a torque converter shudder.If it is diagnosed with a shudder he said they would do a transmission flush and install updated fluid.I said it was a 18 and should already have the updated fluid. He said it depends on the build date. So apparently there are a ton off these out there that were made in 17.He did tell me if it was a Silverado they would replace the torque converter on the first visit, but not on the Vettes. He told me they receive Silverados everyday with this problem and they had 5 of them in the bays right now,and it might take a while to get to mine. Its not just Silverado's and Corvettes either. There was a Colorado parked right in front of me with a shudder problem that he pointed out to me.So If they are replacing the converters on the trucks, why not the Vettes? Sounds like it's too expensive on the Vettes.I will update when I know more.

Originally Posted by GOC

Does the new torque converters actually solve the problem or the new TC is just the same as the original unit and is bound to malfunction after some miles again?

Originally Posted by 89L98

This AFM/Torque Converter issue is to the C7 Gen what the LS7 issue was to the C6 Z06. More GM BS. Only GM really knows the numbers of complaints nationwide. Unfortunately, as the miles pile up more failures will occur. An extended warranty is a must with these A8s. Meanwhile, I would not drive an A8 in eco mode, ever.

Originally Posted by MidLife+

Just an FYI - AFM is active in all drive modes not just Eco. The only way to disable AFM (other than a Range) is to put it in manual mode and paddle shift. I have had both the flush and TC replaced. I still have a shudder. I just got my range this week so I test to see if the shudder is still there with it installed.

Originally Posted by falcon5619

I have not heard of the A6 experiencing this issue but I could be wrong. Although the A8 has this issue in all the GM vehicles that use it. It is AFM, they ruined a great transmission with that fuel saving tech that really doesn't save that much fuel. Ask the folks using the Range device.

Now, if you like to row your own gears the Tremec M7 is a sweet transmission and you never really hear bad things about it. It sounds like manuals will be collectors items soon so might as well pick one up. :-)

Originally Posted by bjones7131

Question: with the range device plugged in, does the TC still lock and unlock? Have heard it is still active but not nearly as much, true or false. Thanks

Originally Posted by stevesrubyred93

Here is another update. I picked the car up on Saturday. they did the flush and they told me to drive it 500 miles. He said that if I still have problems, they would replace the torque converter. I don't have to drive it 500 miles it's still shuddering when I accelerate. It does shift smother, but still have a shudder vibration. I have ordered a Range unit and it is supposed to arrive Thursday.I'll try it, but I think the converter will need to be replaced.This Sucks.

Originally Posted by macjac69

So did the Range give you any improvement?

Originally Posted by 16/C7Z

OP. This isn't gonna fix it. Your car has the new fluid fron factory. There's another issue rear end torque tube etc.

they need to diagnose this properly

Originally Posted by NSC5

The shudder comes from the lockup clutch in the converter not "locking" in the manner expected because of increased wear from the constant on/off modulation it experiences during V4 operation. To a lesser extent these "micro-slips" of the friction clutch are used when engaging the lockup clutch in normal use but this is the same smooth engagement method GM has been using for many years and the wear from this portion of the operation is so minimal that the lockup clutch material will easily last through the normal lifespan of the transmission.

As the lockup clutch wears, it no longer grips as expected so the transmission controller commands greater lockup force which results in harsh engagement. When shudder starts your lockup clutch is in a cycle of constant greater slippage than expected followed by an abrupt harsh lockup as engagement pressure is ramped up to prevent the unexpected slippage and this constant dance of slip then hard lock that occurs during AFM operation creates shudder. The friction modified fluid GM now uses helps to mask some of the problem but the lockup clutch material in the torque converter is still being stressed under a severe duty cycle.

A lockup clutch was added to torque converters many years ago as a method to increase fuel economy by preventing the normal power loss that occurs in the converter at cruising speed and this also reduced heat buildup in the converter because the power lost in the converter gets converted to heat. It is very good at accomplishing its original intended purpose but not so much with the perverted AFM system GM uses. Just as the converter clutch slip is used to mask the additional vibration and harshness from operating a V8 as a V4 the new fluid is designed to mask the effects of utilizing a lockup clutch in a manner/duty cycle not originally intended. The problem could be addressed by either leaving the lockup clutch locked in AFM mode but then the vibration would be too noticeable to vehicle occupants OR just leave the clutch disengaged during AFM operation but then the very minimal mileage increase from V4 operation would probably turn into a mileage loss due to power lost in the open converter.

The best solutions so far are to either use a Range module or drive in manual mode or move to Europe because the A8 equipped Corvettes for that market only use AFM when eco mode is selected just like the M7 models sold in the U.S.