[Kyletech]

So I have found a 2017 2ss Auto 8 speed that is out of state and I have a buddy that can go test drive the car for me so I am wondering what to tell him to look for to tell if the car has the problems that are common with the 8 speeds.

Thanks in advance!

[arpad_m]

Here's a checklist for some known potential issues off the top of my head:

- Torque converter shudder: drive in 7th or 8th gear at low speed (40-50 mph) and low throttle, listen and feel for a sense of vibration similar to driving over rumble strips; can be periodic or, in worse cases, continuous

- Jerky initial shift: after a cold start, switch to tour mode and take off, first slowly then increasingly more aggressively after coming to a stop each time to trigger the 1->2 shift and see if it's prolonged and jerky or smooth

- Jerky uphill downshift: drive onto an incline in 3rd gear (10-15 mph-ish) and slow down further to trigger a downshift to 1st, make sure this is smooth and the car doesn't lurch forward or backward during the shift

- R <-> D shock: after a cold start, shift from reverse to drive and back while the car is standing still on a level surface (to avoid hill start assist from kicking in), check for a small lurch or a creaky extended shift

[LT4Greg]

The SS might have had the fluid change done already so it maybe good to go since 2017 but still needs to be checked.

[FlukeSS]

Originally Posted by arpad_m

Here's a checklist for some known potential issues off the top of my head:

- Torque converter shudder: drive in 7th or 8th gear at low speed (40-50 mph) and low throttle, listen and feel for a sense of vibration similar to driving over rumble strips; can be periodic or, in worse cases, continuous

This can occur at different speeds ranging from 25mph to 80mph. And its not gear dependent. You'll feel a vibration in the gas pedal with steady or very mild acceleration until the car gets over a speed hurdle. In my 2016's case it was 50mph and 70mph. Once you cross a little over that special speed you'll feel the shuddering vibration stop in the gas pedal, and you might be able to hear it a bit. And ya rumble strips is the best description of the sound.

Here's the TSB for it: https://www.tsbsearch.com/Chevrolet/16-NA-175

[DamonZ28]

You can check CarFax to see if a converter flush has been performed. When I was looking at getting a 6th gen, I always looked through the CarFax to see if it had been done. I saw a few that had it reported. Of course, it's only on there if it's been reported, don't know how accurate it is.

[arpad_m]

Originally Posted by FlukeSS

This can occur at different speeds ranging from 25mph to 80mph. And its not gear dependent. You'll feel a vibration in the gas pedal with steady or very mild acceleration until the car gets over a speed hurdle. In my 2016's case it was 50mph and 70mph. Once you cross a little over that special speed you'll feel the shuddering vibration stop in the gas pedal, and you might be able to hear it a bit. And ya rumble strips is the best description of the sound.

Here's the TSB for it: https://www.tsbsearch.com/Chevrolet/16-NA-175

Yeah, but based on the majority of reports, the shudder first starts in 7th/8th at the speeds I mentioned, if that range is clear during the test drive, the shudder hasn't even begun yet, so IMO that's the best and easiest thing to check quickly.

Also, checking service history for fluid exchange is useful, if the latest flush was done on that trans after the end of Jan 2019, chances are the dealership already used the correct fluid (Mobil 1 Synthetic LV ATF HP, part number 19417577).

There is a newer TSB with more information for this, by the way, the number is 18-NA-175 (and even this one had multiple revisions).

[Efi69Cam]

The tach will move a few rpm in sync with the shudder as the converter lockup slips

[ctrlz]

The specific indicator GM advises is a vibration peak around 24 Hz (+/- 2 Hz). This is detected with a picoscope, a pretty specialized tool.
Unfortunately there can be a lot of car vibrations in this frequency range. Probably the best "seat of the pants" test would be for someone who has had the problem to drive the car.
Here's the bulletin:
https://gm-techlink.com/?p=11127

[classicrockr]

Mine has a slight vibration when im driving steady at 1100- 1500 rpm with my foot on the gas pedal. Doesn't matter what gear, it's a specific rpm range with mine. Had the flush done & no metal shavings were found, so im not sure if mine really has the infamous "A8 shudder" or not

[arpad_m]

Originally Posted by classicrockr

Mine has a slight vibration when im driving steady at 1100- 1500 rpm with my foot on the gas pedal. Doesn't matter what gear, it's a specific rpm range with mine. Had the flush done & no metal shavings were found, so im not sure if mine really has the infamous "A8 shudder" or not

When was that flush done and what fluid was used? I'm asking because the correct Mobil 1 fluid came out in Jan 2019, anything done with previous fluid stock would still be susceptible to water retention and eventual shudder.

[PBB66]

Mine is just a case study of one (2018 SS), but I find the shudder emerges around 1700 rpm. Various speeds, yes. But RPM range is pretty consistent 1650-1750 or so.


31k now on the clock, doing first flush service.

[Cwells22]

I have a 2016 2SS that only has 2700 miles on it. I have had it since new. I have not noticed any shudder. Is it recommended to have the transmission flushed anyway before the shudder happens or is there a possibility I may not have an issue?

[arpad_m]

Originally Posted by Cwells22

I have a 2016 2SS that only has 2700 miles on it. I have had it since new. I have not noticed any shudder. Is it recommended to have the transmission flushed anyway before the shudder happens or is there a possibility I may not have an issue?

Left untouched and running the original transmission fluid, all 8L90 and 8L45 units have the potential to develop the issue with no exceptions. If you think your car is somehow exempt or a lucky unicorn, rest assured it is not.

Some cars experience these issues early, others much later, even past powertrain warranty mileage (60K), because there are significant differences in usage patterns, climate (humidity and temperatures) driving styles etc. I had the dealership do preventive flushes on my car back in 2018, then again in 2019 when the correct fluid came out, plus my 8L90 is tuned properly, so I have not experienced the shudder, and very-very likely won't.

Since your mileage is very low and thus your torque converter clutch most probably in good shape, I recommend that you immediately get the flush with the proper Mobil 1 Synthetic LV ATF HP fluid (part number 19417577) and be done with this problem.

The applicable GM service bulletin is 18-NA-355 if you need ammunition for warranty coverage (even though your car is out of powertrain warranty, this is a provable preexisting condition, so you might have a case---be adamant and good luck).

[302crossram]

Originally Posted by Cwells22

I have a 2016 2SS that only has 2700 miles on it. I have had it since new. I have not noticed any shudder. Is it recommended to have the transmission flushed anyway before the shudder happens or is there a possibility I may not have an issue?

Arpad is 100% right, get that tainted piss out of there.
7yo fluid starts to lose most of the beneficial additives anyway