2018 transmission shudder, lucky me
#21
Burning Brakes
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.
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Maxie2U (10-02-2018)
#22
Burning Brakes
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?
#23
Burning Brakes
Another thing to keep in mind is that this TC shudder issue shows up on A8s all across the different GM vehicles using it. Denalis, Tahoes, Trucks, Camaros, etc. I had a new 2016 Camaro 2SS and sure enough right around 4500 miles I am cruising on the highway and here it comes...call it shudder, rumble strips, whatever but it is very disconcerting and at that point you know it will only get worse from there. Triple Flush, then order a new TC and pray it doesn't come back. Some try to get a Range device on the car right after they get a new TC to help avoid the issue from repeating. Now, if new fluid is working then so be but it must be performing some magic to help reduce the shudder to lower levels or whatever but I hope it offers a long term fix.
#24
I'm really wanting and am in the market for a C7, it would be vette number 12. As I'm reading and researching, this AFM issue really has me second guessing a purchase. Am I correct in understanding that this is an isolated issue not a "when not if" issue which has been magnified by those coming to the board to sound off? Surely the percentage of problem cars has to be quite small. Are the 2014 models with the A6 transmission afflicted by the same issue? Any help/reassurance/opinions would greatly appreciated.
Mike
Mike
#25
Instructor
My 18GS hasn't had any shuddering that I can feel. I'm at 7800 miles now and the only issues I can relate to AFM are a squeak noise from behind me when it switches to V4, and a constant tick at idle that I've been assuming is coming from one of the AFM lifters. This tick is too slow to be the fuel pump in my opinion, but they say it's normal.
The shop foreman at my local dealer is putting in a request for help from the engineers to diagnose that squeak sound now.
The shop foreman at my local dealer is putting in a request for help from the engineers to diagnose that squeak sound now.
#26
My 18GS hasn't had any shuddering that I can feel. I'm at 7800 miles now and the only issues I can relate to AFM are a squeak noise from behind me when it switches to V4, and a constant tick at idle that I've been assuming is coming from one of the AFM lifters. This tick is too slow to be the fuel pump in my opinion, but they say it's normal.
The shop foreman at my local dealer is putting in a request for help from the engineers to diagnose that squeak sound now.
The shop foreman at my local dealer is putting in a request for help from the engineers to diagnose that squeak sound now.
The squeak from the additional AFM sound control valves has been reported by others and replacement will cure it at least for some time. These valves live in a rough position in the exhaust system and don't stand up well to the heat of the exhaust when driven in a spirited fashion and even if they are open they still get hot. They were never used on the Z06 because they simply won't stand up to the heat and those who track the other models cook them regularly.
I would keep your torque converter clutch in good health by either leaving the transmission in manual mode or using a Range module. With AFM, regardless of the magic fluid used, it is a question of when and not if the converter lockup clutch will suffer enough wear to create enough slippage to cause shudder. If you only plan to keep the car for a short time it isn't an issue but if you like your Corvette and plan to hang onto it for some time the slight fuel mileage gain from V4 mode operation isn't worth having to have your car largely disassembled to replace the torque converter once wear reaches the point where friction modified fluid can no longer mask the underlying problem. The use of AFM itself is questionable but the attempt to minimize vibration of the engine running in V4 mode via abuse of the converter clutch was a terrible idea and it is a problem across the GM product line and not limited only to the Corvette.
Last edited by NSC5; 09-13-2018 at 10:04 AM.
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Jeffer (10-05-2018)
#27
Drifting
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"
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"
#28
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Hope you get this resolved. I can imagine your frustration after spending that much on a car.
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stevesrubyred93 (09-15-2018)
#29
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 !!
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 !!
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rvan (09-19-2018)
#31
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.
#32
Instructor
#34
Burning Brakes
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. :-)
#35
Race Director
Listen, the good news bad news here is this...
they know what caused it. They addressed it with the new fluid formulation.
If it needs a new converter? You'll never know the car was apart of the tech is worth a dam.
just get it done and move on.
sucks that some early 18s didnt receive new fluid.
they should be swapping the fluid on delivery so they dont have to deal with this nonsense later.
gm hoping people dont realize it and keep driving lol unreal..
just had my 16 (10 15 build) 8spd Sierra converter replaced and fluid flushed new filter etc at 25k miles. Drives BETTER than new.. no bs. So just have it done (and dont watch).
they know what caused it. They addressed it with the new fluid formulation.
If it needs a new converter? You'll never know the car was apart of the tech is worth a dam.
just get it done and move on.
sucks that some early 18s didnt receive new fluid.
they should be swapping the fluid on delivery so they dont have to deal with this nonsense later.
gm hoping people dont realize it and keep driving lol unreal..
just had my 16 (10 15 build) 8spd Sierra converter replaced and fluid flushed new filter etc at 25k miles. Drives BETTER than new.. no bs. So just have it done (and dont watch).
#36
Team Owner
it's funny to read that even with all the examples of bad A8 trannies, people are willing to risk it because they don't or can't drive a MN7.
#37
Aside from our physically disabled C7 brethern, I think most of the A8 buyers don't give buying the auto a second thought. They're so happy to get a C7, they never gave the lack of the manual a thought. They've probably been driving an auto for so long, they're probably not thinking straight. I think the majority thought the C7 only comes as an auto trans.
Last edited by Skid Row Joe; 09-14-2018 at 12:15 AM.
#38
Le Mans Master
I’m on the vette, Camaro and Tahoe/Yukon forums. This A8 has been a curse on GM buyers since 2015. Some play it off like it’s “just a handful” of people, but the number of failures are ridiculous. My vette and Camaro are manuals (luckily, no back or leg issues for me, I can enjoy my manuals) and when I was in the market a couple months back for a 16/17 low mileage SUV, the Tahoe was my only option as the Yukon has the dreaded A8 (a whole lot of pissed off Yukon owners on the forums). Let’s hope the A10 story is a better one.
#40
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I'm really wanting and am in the market for a C7, it would be vette number 12. As I'm reading and researching, this AFM issue really has me second guessing a purchase. Am I correct in understanding that this is an isolated issue not a "when not if" issue which has been magnified by those coming to the board to sound off? Surely the percentage of problem cars has to be quite small. Are the 2014 models with the A6 transmission afflicted by the same issue? Any help/reassurance/opinions would greatly appreciated.
Mike
Mike
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Slynky (09-14-2018)