[wrankin]

Follow. Mine started doing this as well. Called and scheduled an appointment. The service writer confirmed this problem on trucks too, and said I didn't have to demonstrate it.

Bill

[thehartfive]

Well mine went in today for the notorious shudder! Also second time for the loose shark fin antenna, and rear deck pack rattle where the speakers are. Rattling when hitting bumps or on certain songs😡 Not happy!

[Cameron27]

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[17txcamaross]

The slight vibrations when stopped may just be from the engines low RPMs at idle.

I also have the extremely hard shifts from Park to Reverse or Drive. Feels like I've been rear ended about 1/4 the time. Dealer claims this is due to pressure build up in the lines. I also can't imagine this being good for the transmission or any mounts on the vehicle.

As for TSBs, my car is currently at the dealership (yesterday) for replacement of the torque converter. This is GMs current "fix" for the transmission shudder while driving. I don't feel like this is a permanent fix as I believe they are only replacing with the exact same part. Unless it is a defective part it will only be a matter of time before this new torque converter is ruined.

A little background I have 7,600 miles on my 2017 2SS A8. I do not have mag ride...not sure whether this makes any difference. Initial shuddering began around 2k-2.5k miles. GM flushed system per TSB. Shudder returned at approx. 6-6.5k miles. However, for the first 500 miles of returned shudder it was too intermittent to bring into the dealer. Once the shudder was consistently present Hurricane Harvey devistated the Houston area and loaner cars were a thing of dreams.

I will update once I get my car back...hopefully later this week. Until then I will enjoy driving the 2LT V6 although I already miss the added power and V8 rumble.

Originally Posted by Cameron27

Does this issue relate to vibrations in the car while at stop lights? I get minor ones.

I am really worried about the auto transmission in this car:

- subpar, but acceptable when downshifting from 4 to 3 manually
- horrendous when downshifting from 3 to 2 manually
- bad in parking lots / slow speeds in any auto mode
- vibrations / shudders when going into/out of v4 mode
- huge backlash lugs when going up hills at slow speeds, car goes from gear 3 to 1 no warning
- sometimes in full auto mode, the car shifts up gears rather poorly (I could do a smoother job in a manual)
- switching from park/neutral/drive/reverse while not moving can shake the whole car, feels like those shifts aren't good for the car

I have yet to experience vibrations while moving, but I do experience some while at stop lights, the vibrations seem normal enough but not really high quality (considering my previous vehicle which was less than 50% of the price didn't do that)... 8 weeks into ownership.

Would love to hear about any TSB's related to the auto transmission, and actually getting REAL RESULTS. A transmission fluid change is one thing, that's something I might ask for... but I'm talking about real results, actual proper warranty work. I got work done on my electronic steering & they fixed it perfectly, I'd like to feel the same about my transmission.

[Cameron27]

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[killervette666]

Recently had the flush done my 17 1SS (3.7k miles, 08/16 build) and it drives so much smoother and no more vibrations, time will tell if it holds. If your having trouble with the dealership I would recommend printing out the TSB and putting it on the desk in front of them.

I've also been reading a LOT about this issue on this forum, the Corvette forums (since they got the 8L90 before us in 2015), and the CTSV forums, and it turns out that GM has gone through 3 different torque converters for the LT1. Apparently the earlier 2 versions of the converter required a straight up replacement at any sign of shudder, but the newest version (Part #24280631 TC) is the one that requires them to first do the triple flush. There's no consensus on the cause, some suggest that GM used the wrong transmission fluid, others suggest that AFM/DOD is paired with software that pulses the converter to lock/unlock constantly to smooth out the transition from V4-V8 (with manual drivers reporting that in eco mode the V4 transition is really rough and would be a huge bother for A8 buyers if it wasn't smoothed out somehow). This theory makes the most sense, with the rapid lock/unlock causing excess wear. However, it is interesting that overall it seems like only 5-15% of cars are affected with no real rhyme and reason, and with some people even having received multiple bad converters, some having failures at higher mileage, and some having failures early on. A number of GM techs on different forums have also reported that they've done a fair number of TC replacements but it's definitely not an across the board failure situation. Just thought I would summarize for everyone what lots of research has led me to.

[black96lt1]

got a couple 100 miles on mine after the flush and update. 100% better. Zero vibrations and while mine never shifted "rough" it does shift a bit smoother.

[Adrian97c]

Originally Posted by black96lt1

got a couple 100 miles on mine after the flush and update. 100% better. Zero vibrations and while mine never shifted "rough" it does shift a bit smoother.

Mine still shifts like a bucking bronco


Sent from my iPhone using Tapatalk

[17txcamaross]

Just got my Camaro back from the shop 30 minutes agofrom a torque converter replacement. Drove about 5 miles back to work and I have to say it shifts 1,000 times better and the vibration appears to be gone. Now, mind you with the initial flush it took a couple thousand miles to start up again.

I will have to wait until the morning to see if the shifting from park to drive is still horrible.

[Cameron27]

[.

[wrankin]

Originally Posted by wrankin

Follow. Mine started doing this as well. Called and scheduled an appointment. The service writer confirmed this problem on trucks too, and said I didn't have to demonstrate it.

Bill

The service manager seemed to take ownership of the issue. He called personally and asked me a bunch of questions. He was able to duplicate the problem with the computer hooked up. They changed the filter, flushed the fluid changing it to synthetic. He said GM should have used synthetic in the first place on these transmissions. I am to drive 200 to 300 miles and report back with the results. I hope this takes care of it.

Bill

[Stex]

Originally Posted by wrankin

The service manager seemed to take ownership of the issue. He called personally and asked me a bunch of questions. He was able to duplicate the problem with the computer hooked up. They changed the filter, flushed the fluid changing it to synthetic. He said GM should have used synthetic in the first place on these transmissions. I am to drive 200 to 300 miles and report back with the results. I hope this takes care of it.

Bill

Please give us some feed back.

[Darth Martel]

I have an anonymous source at a GM test facility in Pontiac (Michigan) that told me they are testing the A8 for this issue with the torque converter and they still can't figure out what the deal is. It's good to know that it's at least being investigated but, at this point, not knowing what's causing it, after over a year and a half of complaints, doesn't give me much confidence. I'm getting mine triple flushed next week and if that doesn't fix it, I'm going to spring for an aftermarket torque converter. I love the car otherwise so, it's a keeper. I don't mind investing in it since I plan on keeping it.

[Chutzpah]

Originally Posted by Darth Martel

I have an anonymous source at a GM test facility in Pontiac (Michigan) that told me they are testing the A8 for this issue with the torque converter and they still can't figure out what the deal is. It's good to know that it's at least being investigated but, at this point, not knowing what's causing it, after over a year and a half of complaints, doesn't give me much confidence. I'm getting mine triple flushed next week and if that doesn't fix it, I'm going to spring for an aftermarket torque converter. I love the car otherwise so, it's a keeper. I don't mind investing in it since I plan on keeping it.

Originally Posted by killervette666

Recently had the flush done my 17 1SS (3.7k miles, 08/16 build) and it drives so much smoother and no more vibrations, time will tell if it holds. If your having trouble with the dealership I would recommend printing out the TSB and putting it on the desk in front of them.

I've also been reading a LOT about this issue on this forum, the Corvette forums (since they got the 8L90 before us in 2015), and the CTSV forums, and it turns out that GM has gone through 3 different torque converters for the LT1. Apparently the earlier 2 versions of the converter required a straight up replacement at any sign of shudder, but the newest version (Part #24280631 TC) is the one that requires them to first do the triple flush. There's no consensus on the cause, some suggest that GM used the wrong transmission fluid, others suggest that AFM/DOD is paired with software that pulses the converter to lock/unlock constantly to smooth out the transition from V4-V8 (with manual drivers reporting that in eco mode the V4 transition is really rough and would be a huge bother for A8 buyers if it wasn't smoothed out somehow). This theory makes the most sense, with the rapid lock/unlock causing excess wear. However, it is interesting that overall it seems like only 5-15% of cars are affected with no real rhyme and reason, and with some people even having received multiple bad converters, some having failures at higher mileage, and some having failures early on. A number of GM techs on different forums have also reported that they've done a fair number of TC replacements but it's definitely not an across the board failure situation. Just thought I would summarize for everyone what lots of research has led me to.

Thanks for the research guys.

I'd really like to know what to expect long term from a GM on this issue. Many people, including me, drive very few miles ( 4750 6/3/2016 build date) and store their cars for 50% +/- of the year. Meaning we could be out of warrantee when and if a TQ issue does arise. This could easily turn into a 8 speed class action suit, which would be unfortunate. If GM can't or won't permanently fix rattling NPP systems, I'm not holding out hope that a "real" fix will occur for the TC's. I truly hope that I'm wrong, on both counts.