stevesrubyred93

My 2018 with 6500 miles on it began shuddering about a month ago. I thought GM had this figured out by now. It also has picked up a nice vibration on acceleration. Made an appointment with local dealer today, hopefully get this fixed on the first go around. I also had a 2014 Silverado with the same issue. The issue never really got resolved. The changed the ring and pinion and it quieted it down enough so they called it repaired. I traded it in for the 18 Vette. This is my 4th corvette that I've owned. I love the car ,but am very disappointing with this issue. Has anyone else had an transmission issues with their 18 or 19? I've seen a ton of issues with the 15 and 16's, but none with the 18's.

Slynky

I was considering an A8 for my 19 order but it seems like I read people with 18s and 19s were both experiencing it. So, I ordered the manual--no biggie, every car I've ever driven has been a stick anyway.

Rebel Yell

Well damnit, I thought GM had this crap figured out in the '18's also. My '16 A8 started the same thing at approx. 4500 miles. I ordered a Range V4 disabler, plugged it in, and that took care of the problem. No V4, no shudder. Good luck Steve, and I'm gonna welcome you to the forum with your first post after being a 10 year member. That's got to be some kind of record.

stevesrubyred93

This was my first brand new Vette purchase and like all the other Vettes Iv'e had, I was amazed at the performance.I won't give up on Corvette, Its worth the pain.

Slynky

There is a sticky thread that you might want to check out.

I've looked for examples of 18s and 19s doing this and although I thought I remember reading it somewhere, I can't find it now. There is one post in that long thread that "suggests" that the part number in question hasn't changed in production models for the last several years.

Also, it seems a lot of people just buy that range AFM controller thingie (don't remember the name) to stop the vehicle from passing in and out of V4 mode (which some people attribute the shudder to).

Anyway, sorry to hear--hope it's an easy fix for you !!

64Corvette

Rebel Yell, how do you know that is is actually working and what are some of the added benefits other than eliminating the shudder of adding this disabler? I have a 012 Tahoe and this interest me. Thanks

Rebel Yell

As I said mine started the shudder mess at around 4500 miles. Like others I put off buying the Range for awhile, and read a lot of threads about the unit. Before the Range mine would shudder when transitioning from V4 back to V8 under slight acceleration, or when in cruise going up a hill. It would be worse when the trans would downshift at the same time the engine was going back into V8. It didn't do it every time, but when it did at just aggravated the crap out of me. I mean, it's a 65K car, and it shouldn't do that even if it was a 25K car. With the Range plugged in it smooth sailing as the car should be. Like others have said, mine feels like a completely different car. The tranny changes smoother, and there isn't a hint of the shudder.

Range has finally concurred the problem of the unit causing false CEL's, and draining batteries. Their 8.6.1 version hit the right spot. You can leave it plugged in without any CEL's popping up after start-up, and it has a sleep cycle to stop the battery drain. If you have any questions give Range a call. The're good folks, and helped me with all of my questions.

Check out this thread I just started about the unit, and the mpg's with the unit on.

https://www.corvetteforum.com/forums...nterested.html

falcon5619

C5Driver

Like I have said here many times before you really cant fix a defective design. GM has been throwing many band aids at this transmission but they just don't work. I wish someone would file a class action so at least we could get compensated for our troubles. The LEAST GM could do is REFUND the MSRP price they charged all of us to own this piece of crap tranny over the manual.

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.

kennyjames21

GM isn't going to fix the shudder because they're not gonna take AFM out of all the cars they've already made, and they'll never admit they made a mistake with AFM. But if you look at what they did with the zr1, they basically admitted they made a mistake with AFM by not using it with their supercar. AFM is a terrible technology. It destroys the drivetrain of the cars that use it to save a minuscule amount of gas. Look into some videos where tag talks about how they had to strengthen the driveshaft of the c7 because of all the vibration v4 mode creates due to AFM.

DeAdEnD

This thread makes me think I need to relearn to drive a manual (been 20+ since) and buy a manual C7 instead of the planned A8. Problem is no one I know drives a manual. I would have to relearn on the C7.

bjones7131

I got a Range device and have used it since my car had about 4K on it. I had no symptoms of TC going bad but decided to try and eliminate any at all. Even with the Range device I am told the TC is still at work but not nearly as much so hopefully no issues for a very L O N G time. AFM was a terrible idea, NUTS. I have read the single tranny flush is a possible fix as well but not sure if it is a fix or bandaid. New fluid is supposed to work better on the TC.

23/C8Z

Let him produce the diagnostic report first before everyone compares this to the old (pre 18) issues.

I would be shocked beyond belief if it is the torque converter shudder post the new low viscosity fluid and converter changes that issue was fixed late and 17 on the 18s.

any number of other things but not that.

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.

LimeRay

OP of this thread traded one vehicle with the balky A8 in on another with the same crappy tansmission. WTF? SMH. Why people keep buying the A8 is beyond me. "Here GM, take 70K of my money and kick me in the nuts." "Oh, oh, I love the pain, kick me again."

Inferno24

That seems like the best solution to the problem! Not moving to Europe, but reprogramming the vehicle to only allow the AFM to engage while in Eco mode. Is that even possible to do at this point? Could GM rewrite a program and reflash our cars only to engage the AFM in Eco mode?

NSC5

They could but since it was economy certified with the present programming that reprogram won't happen (something which must make the owners of Range very happy). If I were one of the people behind Range I would definitely have the GM folks responsible for AFM on my Christmas card list and probably name my yacht after one of their first born children.

For those of you old enough to have been around for the early days of SNL, Garrett Morris had a famous skit in which he played a Hispanic baseball player and his classic line was, "Baseball been berry, berry good to me" and I imagine some of the people at Range must be thinking "AFM been berry, berry good to me"

nightroddersp

I thought the 17 A8s did require you to have the car in Tour or Eco. I have been using Sport mode on all setting and haven't notice any shutter but I did notice the car leave 1st gear to soon when feathering the gas up to a right hand turn at a red light or stop sign. Push the gas when exiting the turn and it tries to accelerate in second but ends up shifting into 1st then almost immediately shifting back to second.

stevesrubyred93

I will update when I find out what they find. I'm taking it in tomorrow evening. My neighbor who works at another local dealer asked their service dept. if they are seeing any issues with 18's and he said he hasn't seen any .Hopefully it is not a converter issue.