A8 shudder, stutter, warble, rumble strips
Le Mans Master
Joined: Aug 2015
Posts: 8,243
Likes: 4,617
From: Southwest Florida
We'd be happy to confirm the issue and proceed with the repairs if the shudder meets GM's criteria. The newest version of the bulletin requires a snap shot of the data showing the vibration is above a certain threshold. If it is, we're good to go.
With that being said, 80% of the vehicles we road test (Camaro, Corvette, Cadillac, Truck and SUV's) do not meet the minimum threshold to perform the flush. We literally see at least one vehicle per day for this "issue" so it's nothing new to us, but we have to be able to verify (with data) that it's severe enough to warrant repairs. Many of the people coming in have a slight shudder, but they read on the forums about it and more or less just want a free fluid flush.
If the vehicle is under bumper to bumper warranty, GM will pay us the 3/10ths of an hour diagnostic time even if we can't prove the level of shudder is above GM's limit. If the car is outside the 3/36 bumper to bumper, GM does not allow us to submit the diagnostic time if the car is not severe enough so that time is the customer's responsibility. If the shudder is excessive and we can obtain the snap shot, all costs are paid by GM and the customer is not responsible for anything.
With that being said, 80% of the vehicles we road test (Camaro, Corvette, Cadillac, Truck and SUV's) do not meet the minimum threshold to perform the flush. We literally see at least one vehicle per day for this "issue" so it's nothing new to us, but we have to be able to verify (with data) that it's severe enough to warrant repairs. Many of the people coming in have a slight shudder, but they read on the forums about it and more or less just want a free fluid flush.
If the vehicle is under bumper to bumper warranty, GM will pay us the 3/10ths of an hour diagnostic time even if we can't prove the level of shudder is above GM's limit. If the car is outside the 3/36 bumper to bumper, GM does not allow us to submit the diagnostic time if the car is not severe enough so that time is the customer's responsibility. If the shudder is excessive and we can obtain the snap shot, all costs are paid by GM and the customer is not responsible for anything.
is the flush covered if you have a GM extended warranty?
.
Last edited by Maxie2U; Nov 24, 2019 at 12:46 PM.
Pro
Joined: Apr 2018
Posts: 677
Likes: 145
We'd be happy to confirm the issue and proceed with the repairs if the shudder meets GM's criteria. The newest version of the bulletin requires a snap shot of the data showing the vibration is above a certain threshold. If it is, we're good to go.
With that being said, 80% of the vehicles we road test (Camaro, Corvette, Cadillac, Truck and SUV's) do not meet the minimum threshold to perform the flush. We literally see at least one vehicle per day for this "issue" so it's nothing new to us, but we have to be able to verify (with data) that it's severe enough to warrant repairs. Many of the people coming in have a slight shudder, but they read on the forums about it and more or less just want a free fluid flush.
If the vehicle is under bumper to bumper warranty, GM will pay us the 3/10ths of an hour diagnostic time even if we can't prove the level of shudder is above GM's limit. If the car is outside the 3/36 bumper to bumper, GM does not allow us to submit the diagnostic time if the car is not severe enough so that time is the customer's responsibility. If the shudder is excessive and we can obtain the snap shot, all costs are paid by GM and the customer is not responsible for anything.
With that being said, 80% of the vehicles we road test (Camaro, Corvette, Cadillac, Truck and SUV's) do not meet the minimum threshold to perform the flush. We literally see at least one vehicle per day for this "issue" so it's nothing new to us, but we have to be able to verify (with data) that it's severe enough to warrant repairs. Many of the people coming in have a slight shudder, but they read on the forums about it and more or less just want a free fluid flush.
If the vehicle is under bumper to bumper warranty, GM will pay us the 3/10ths of an hour diagnostic time even if we can't prove the level of shudder is above GM's limit. If the car is outside the 3/36 bumper to bumper, GM does not allow us to submit the diagnostic time if the car is not severe enough so that time is the customer's responsibility. If the shudder is excessive and we can obtain the snap shot, all costs are paid by GM and the customer is not responsible for anything.
Last edited by Ruderegime; Nov 24, 2019 at 05:28 PM.
Intermediate
Joined: Aug 2019
Posts: 29
Likes: 16
From: Georgia
I googled the issue and found this..........
We’ve covered the problems of the eight-speed GM transmission on numerous occasions. In fact, we cover a class action lawsuit brought against GM back in April, complaints from owners, and even a recommendation that GM replace the eight-speed altogether with a new unit as quickly as possible. Now, GM Authority has learned that there’s a new fix that seems to be alleviating the eight-speed’s shifting woes outright.
As of July 8th, 2019, GM began using a new type of Mobil 1 automatic transmission fluid for the troublesome transmissions. Customers that complain of shuddering and harsh shifting characteristics in the 8-speed GM transmissions are recommended for a trans fluid flush. As of August 7th, GM dealers should also be flushing all potentially affected new vehicles on the lot.
The GM 8L45 eight-speed automatic transmission
According to TSB (Technical Service Bulletin) 18-NA-355, the latest update addresses “torque converter clutch (TCC) shudder conditions on 8L45 and 8L90” eight-speed automatic transmissions, RPO codes M5N, M5T, M5U, and M5X. Affected vehicles include Chevrolet, GMC and Cadillac vehicles, as follows.
Chevrolet
2015 – 2018 Chevrolet Silverado 1500
2015 – 2019 Chevrolet Corvette
2016 – 2019 Chevrolet Camaro
2017 – 2019 Chevrolet Colorado
GMC
2015 – 2017 GMC Yukon
2015 – 2018 GMC Sierra 1500
2017 – 2019 GMC Canyon
Cadillac
2015 – 2017 Cadillac Escalade
2016 – 2018 Cadillac CT6
2016 – 2019 Cadillac ATS
2016 – 2019 Cadillac ATS-V
2016 – 2019 Cadillac CTS (excluding V-Sport models)
2016-2019 Cadillac CTS-V
The issues with the 8-speed GM transmission are two-fold. First, some customers report the transmission shuddering frequently. Secondly, the shifts are very harsh between first to second, and then second down to first, especially when accelerating and the transmission is upshifting or decelerating and the transmission is downshifting. These conditions are most commonly observed under light and medium throttle applications, and as often during full throttle applications.
However, a new fluid flush appears to fix the issues, with some customers beginning to report a dramatic change in shift quality after swapping out the old juice. If the flush doesn’t fix the issue, the next step may be to replace the torque converter, which could be glazed.
Read more: http://gmauthority.com/blog/2019/08/...#ixzz66IfjzCCL
We’ve covered the problems of the eight-speed GM transmission on numerous occasions. In fact, we cover a class action lawsuit brought against GM back in April, complaints from owners, and even a recommendation that GM replace the eight-speed altogether with a new unit as quickly as possible. Now, GM Authority has learned that there’s a new fix that seems to be alleviating the eight-speed’s shifting woes outright.
As of July 8th, 2019, GM began using a new type of Mobil 1 automatic transmission fluid for the troublesome transmissions. Customers that complain of shuddering and harsh shifting characteristics in the 8-speed GM transmissions are recommended for a trans fluid flush. As of August 7th, GM dealers should also be flushing all potentially affected new vehicles on the lot.
The GM 8L45 eight-speed automatic transmission
According to TSB (Technical Service Bulletin) 18-NA-355, the latest update addresses “torque converter clutch (TCC) shudder conditions on 8L45 and 8L90” eight-speed automatic transmissions, RPO codes M5N, M5T, M5U, and M5X. Affected vehicles include Chevrolet, GMC and Cadillac vehicles, as follows.
Chevrolet
2015 – 2018 Chevrolet Silverado 1500
2015 – 2019 Chevrolet Corvette
2016 – 2019 Chevrolet Camaro
2017 – 2019 Chevrolet Colorado
GMC
2015 – 2017 GMC Yukon
2015 – 2018 GMC Sierra 1500
2017 – 2019 GMC Canyon
Cadillac
2015 – 2017 Cadillac Escalade
2016 – 2018 Cadillac CT6
2016 – 2019 Cadillac ATS
2016 – 2019 Cadillac ATS-V
2016 – 2019 Cadillac CTS (excluding V-Sport models)
2016-2019 Cadillac CTS-V
The issues with the 8-speed GM transmission are two-fold. First, some customers report the transmission shuddering frequently. Secondly, the shifts are very harsh between first to second, and then second down to first, especially when accelerating and the transmission is upshifting or decelerating and the transmission is downshifting. These conditions are most commonly observed under light and medium throttle applications, and as often during full throttle applications.
However, a new fluid flush appears to fix the issues, with some customers beginning to report a dramatic change in shift quality after swapping out the old juice. If the flush doesn’t fix the issue, the next step may be to replace the torque converter, which could be glazed.
Read more: http://gmauthority.com/blog/2019/08/...#ixzz66IfjzCCL
1st Gear
Joined: Nov 2019
Posts: 1
Likes: 0
I just bought a 2019 GS with the auto and have noticed that when it is in 4 cylinder mode, I get a shudder which happens about once every 30 seconds or so from the car. It is not severe, but it's enough to get my notice constantly. It also happens when it drops to V4 or up to V8. Doesn't happen in 8 cylinder mode. I really hate buying an expensive brand new car and having issues. Didn't have a single issue with my 2012 GS.
Le Mans Master
Joined: Feb 2010
Posts: 7,798
Likes: 314
From: Santa Fe Tx
My experience is as follows:
1. A8 Transmission shudder in a 2016 Z51. Shudder appeared with less than 1000miles. Took to Parkway Chevy in Tomball Tx. They replaced TC. Problem reappeared at 15k miles. Took to Demontron Chevy in Texas City(cause I moved) at 18k miles they did triple flush and reprogramed transmission? seems to have fixed it really good- really different feel.They said latest TSB says there is no issue with TC, it is with fluid. The old fluid would allow condensate moisture to mix with fluid which changed viscosity??? New fluid does not do this???
2. Had irritating noise from engine when in V4mode under slight load. Noise went away as soon as engine went to V8. Demontron Chevy changed belt tensioner. Issue is gone- can not even tell when in V4 or V8.
really feel good about driving the car now.
1. A8 Transmission shudder in a 2016 Z51. Shudder appeared with less than 1000miles. Took to Parkway Chevy in Tomball Tx. They replaced TC. Problem reappeared at 15k miles. Took to Demontron Chevy in Texas City(cause I moved) at 18k miles they did triple flush and reprogramed transmission? seems to have fixed it really good- really different feel.They said latest TSB says there is no issue with TC, it is with fluid. The old fluid would allow condensate moisture to mix with fluid which changed viscosity??? New fluid does not do this???
2. Had irritating noise from engine when in V4mode under slight load. Noise went away as soon as engine went to V8. Demontron Chevy changed belt tensioner. Issue is gone- can not even tell when in V4 or V8.
really feel good about driving the car now.
