[OB0001]

2018 SS no shutter ran a 11.87@117mph last week on street tires and a 20mph head wind. GPI tuned/trans tune E85,LT2 intake, Roto fab CAI, Soler throttle body stock ported.

[truckrglenn]

At 30,000+ mine started the shudder, changed the fluid and filter myself, no issues since.

[TP2SS]

2016 2SS bought in Dec '19 with 1880 miles. Didn't shudder. Had the TSB done at a Chevy dealer in '20 as a preventive measure. Now 7700 miles no issues.

Wife has a '16 CTS AWD 2.0T. It started the shudder at 41k and I took it to Caddy immediately. TSB done and no issues since.

A lot depends on how quickly the owner did the TSB after the shudder appeared, and when it did (year). They didn't figure out the absolute fix until '18 with TSB 18-NA-355.

I advise all my friends with this A8, or ones considering buying a used A8 car to have it done even if they have to pay OOP for it, regardless of whether it's exhibiting the symptoms.

[BluinSC]

71k miles not problem with the trans. Had to replace the rear diff in December though.

[arpad_m]

Originally Posted by TP2SS

2016 2SS bought in Dec '19 with 1880 miles. Didn't shudder. Had the TSB done at a Chevy dealer in '20 as a preventive measure. Now 7700 miles no issues.

Wife has a '16 CTS AWD 2.0T. It started the shudder at 41k and I took it to Caddy immediately. TSB done and no issues since.

A lot depends on how quickly the owner did the TSB after the shudder appeared, and when it did (year). They didn't figure out the absolute fix until '18 with TSB 18-NA-355.

I advise all my friends with this A8, or ones considering buying a used A8 car to have it done even if they have to pay OOP for it, regardless of whether it's exhibiting the symptoms.

This is great advice Just one minor addition, the "absolute fix" fluid was made available in late January 2019, so any trans flush, single or triple, received prior to that and/or with previous fluid iterations is unfortunately irrelevant and has to be repeated.

[ctrlz]

Originally Posted by CHASLT1

I wonder if anyone really knows what the real prob was with the A8?

Pretty well documented. the fluid used in pre-2019 A8's basically had the wrong chemistry. it attracted water, which led to irregular lubrication of clutches in the torque converter, causing them to chatter and wear irregularly. This situation was reversible if the bad fluid was replaced soon enough.

The reason for different experiences is probably related to things like usage patterns, humidity, etc. I do not think cars with the newer fluid had shudder, which implies that GM's theory for the failure was correct.

[CHASLT1]

Originally Posted by ctrlz

Pretty well documented. the fluid used in pre-2019 A8's basically had the wrong chemistry. it attracted water, which led to irregular lubrication of clutches in the torque converter, causing them to chatter and wear irregularly. This situation was reversible if the bad fluid was replaced soon enough.

The reason for different experiences is probably related to things like usage patterns, humidity, etc. I do not think cars with the newer fluid had shudder, which implies that GM's theory for the failure was correct.

Still odd that some A8's never had a prob and some did.

[arpad_m]

Originally Posted by CHASLT1

Still odd that some A8's never had a prob and some did.

ctrlz already said it, usage patterns, humidity, plus temperature and mileage all make a difference—in other words, unless preventive or corrective action is taken, most likely all A8s would/will be subject to the shudder eventually.

[CHASLT1]

Originally Posted by arpad_m

ctrlz already said it, usage patterns, humidity, plus temperature and mileage all make a difference—in other words, unless preventive or corrective action is taken, most likely all A8s would/will be subject to the shudder eventually.

Well maybe i should do the triple flush on my C7. Sure it won't be cheap. This car has no service history other than the normal oil changes and one trans service.

[ctrlz]

Originally Posted by CHASLT1

Well maybe i should do the triple flush on my C7.

Same situation apparently. Lots of similar posts on corvette forums.

https://www.corvettecare.com/never-h...d-this-good-5/

[xmattyx]

bought my 17 with 9k miles on it, had the flush done right away, no issues since, prob because the mileage was so low.

[CHASLT1]

Originally Posted by xmattyx

bought my 17 with 9k miles on it, had the flush done right away, no issues since, prob because the mileage was so low.

Odd that my 2019 C7 had the shudder at 400 miles and put a Range on it at 150 miles. I got the range on my 2015 C7.

[Joshinator99]

Originally Posted by CHASLT1

Odd that my 2019 C7 had the shudder at 400 miles and put a Range on it at 150 miles. I got the range on my 2015 C7.

Range didn’t guarantee much in my opinion. While keeping it out of AFM mode does reduce commanded slippage in the TCM, the TCC tables still have some slip commanded even outside of AFM mode.

[jamala00]

Mine had the issue when the original owner had it. He had it flushed twice. It's now just about 50k and no issues.