Our 2017 ZA8 is at 4500, maybe 1200 at the track, miles and roaring along. When I read about the A8 issues, I decided it was worth it to purchase an extended warrantee, 5y/50k, zero deductible, less than a set of Sport Cup 2s, and don't worry about it. Take it to the track and drive it like I stole it If it doesn't break by the end of the warrantee, I figure it will likely last me a long time. But if it fails at 55k, it would be reasonable to put it in the "consumable" category along with the tires, brakes and fuel/oil. Frankly it seems like a great deal to have a car like that, track it, and still have a warrantee at all.

 

That's a good attitude. I like it. On my post above, number 7, I forgot to mention I have 41,000 miles on my car and the A8 has been magnificent! And I drive it hard.

 

It seems older cars, most notably 2015-16, have more chance of problems than later ones. Mine was a 2015 (Dec. 2014 build) and had two issues from Day 1:

• Shuddering and tach oscillation in V4 mode while at cruise under light acceleration. This is the classic set of symptoms for a faulty TC, and for the past couple of years the fix was to replace the TC and do a fluid flush. The fix was not always successful in the first two TC revisions and some owners had to endure two and occasionally three TC replacements. GM has produced at least three revisions of TCs, a new one introduced when the previous revision was not successful. The latest TC # to my knowledge is 24280631 and fluid is 19353429 (Mobil 1 HD low-viscosity). As of last spring the fix has been the flush only.
  
  Mine was finally fixed in Feb. 2017 by replacing the TC and fluid, and for the two weeks I owned the car thereafter it worked fine with no more symptoms. By that time I had had enough and bought a new GS M7, as at that time there was no assurance the fix would be permanent, and I would doubt it is even today.
  
  
• Delayed engagement when cold. This may only relate to 2015 models and is covered in TSB #16-NA-14. Mine would do it about once every three months, never in the presence of service personnel, so they refused to effect this fix while the tranny was out of the car for the TC replacement (believe it or not).

As for the percentage of cars affected, it may be higher than we think because some may have the shuddering problem and don't know it, thinking it is just road imperfections. My shuddering was rather innocuous and sporadic at first, getting worse after about a year. By 18 months it was doing it every time I drove the car and was able to demonstrate it to the dealer. I didn't notice the tach oscillation until I read about it here, so some may not have noticed that either.

 

But as I mentioned earlier, is it simply because the newer cars don't have as many miles on them yet for the problem to show up? Or has GM actually made improvements to the 2017s and 2018s that make them less likely to have problems?

 

Thanks fast, I shouldn't have said shutter. It's more of what you feel. There has been speculation that that little grumble could turn into the dreaded TC problems, however I have no idea if that's the case.

 

I think you're right that as mileage accumulates we'll see more reports of problems. That said, mine exhibited the shuddering from Day 1 with <50 miles on the clock, but this is the earliest I've seen so far. As for hardware improvements, it certainly didn't look promising for the first year or so, because as of March 2017 they were on Rev. 3 of the TC. I haven't seen a report of one of these requiring a repeat replacement, but who knows. Mine got the newest (at the time) part #, but not wanting to take the chance I bailed on it after hassling with it for almost two years. In early 2015 they simply didn't know what was going on, but as time progressed and C7s, trucks, SUVs, etc. started developing A8 problems the dealers started to take notice. The SM of the dealer I talked to first wanted me to wait until a sure fix was in evidence, as my symptoms were sporadic and not a big problem. After it got really bad he wouldn't return my phone calls, so I went to dealer #2, who took a ride and said "This is the worst TC shudder I've seen so far," so I had it repaired there.

FWIW, these are the part numbers as of March 2017, presumably in chronological order. My original was 24273061 and the replacement was 24280631. Not sure what cars got the first TC #, as mine was a Dec. 2014 build, but that was six months into the MY. Maybe they saw problems and started the revision sequence just before that. We'll never know, I'm sure.

TC #s: 24264542, 24273061, 24279495, 24280631

 

Look at what data we do have in the sticky post on this subject. There is a chart in the spreadsheet that actually counters this thinking. Seems to be fewer problems as mileage increases and fewer with later years. To me it seems some fixes may have been introduced and that if you're going to have the problem it comes early.