I see a lot of hate about the A8 paddle shift speed, and I'd agree, it's lazy. I thought it'd be worth looking at (a) why that is, and (b) why we care.

For (a), shifting the 8L90E can be broken down into two phases:
- Shift preparation
- Shift execution

The car's smart enough that for a WOT shift, it can do the preparation part in advance. That means when it comes to redline, it can do a shift in the much-talked-about "faster than a DCT" speed. But it needs to be able to prepare in advance. When it can "see it coming", the A8 shifts like nobody's business.

That's why when you pull a paddle at an "unexpected" time there's a lag. It then has to do the preparation and the execution on demand, and only the execution is fast - the preparation take up to a second, or so it seems.

I was explaining this to someone and it made me think - the A8 is thus very fast at shifting at the right time and pretty bad at shifting at the wrong time.

Not to be too much of an apologist, but why do we care how fast the trans shifts at the wrong time?

I don't actually paddle-shift (except on the road course, to manage heat) anyway, so it's not a big deal for me, and maybe that's why I don't really care.

Am I missing a scenario where you SHOULD be upshifting and the car can't have anticipated it and therefore you get the laggy paddle shift in a time/place where a crisp shift would have been better?

In other words, the laggy paddle shift - does it even matter beyond bragging rights?

 

Some say the WOT shifts are not consistent and often leave revs on the table so to speak. Then putting the car in manual mode and user shifting you run a high probability of redlining due to the shift execution as the user runs the car to redline ..
I love the shift speed under WOT. I think we all just want more precise timing when a command is given. The A10 does this very well.

 

Have the trans tuned and all these concerns are gone! Just had my 2017 done and it's fabulous!

 

depending on who did it there's a good chance it will be fabulous right up until it fails.

 

lol that's with any tune.....there are those that can and those who think they can! The only person who touches my tune is the same guy who has done all my gm vehicles including my 9 second CTS-V. I use jeremy formato and highly recommend him to anyone.

 

glad you're happy.

 

To me, it's just one of those things that when you get used to the shift lag, it's not a big deal. I like to play around with manually shifting it and have learned to wind out the rpms, tap the up shift, let off the gas for a nice clean shift, and then back on the gas. It sounds very similar to a manual trans and makes it more fun to tinker around in. At WOT, I think the paddle's do just fine. With that said, I'm good with the stock trans calibration.

 

The same can be said for the M7.

Unless you drive around with your hand on the shifter, it takes much more time to reach for it than to grab a paddle (assuming your hands are always already on the wheel). Despite how sluggish people claim the A8 can be, it's faster or equally as fast as an unplanned manual shift.

As for execution, I'm not a fan of Tremec transmissions and their shift quality.

Next time you think the shift is sluggish, think about how long it would have taken to make the same shift with a manual.

The manual doesn't seem slow because you're doing all the work, and you're moving as fast as you can.

With the auto, it's instant click and wait. Sometimes the wait is a little longer if it's not a WOT upshift in performance or track mode.

 

^^^ I suppose that's true. If you had a passenger riding along who randomly yelled "Shift Now" it'd take as long or longer with the M7.

What that proves, I have no idea :-)

 

Since a ton are failing without being tuned, they only issue is the warranty coverage.

 

A8s don't fail in the Z, only the Stingray it seems. The Z has a beefier torque converter and better clutches that seem to keep it alive.

 

Interesting--I have been playing around with this too. About what RPM are you shifting for non-racing situations?

 

No specific RPM, but generally between 2,000 to 4,000 depending on my mood and how much I want it go growl...here's a little video that I did a while back playing around with it...I used an external microphone taped to the rear of the car so that it got a reasonable sample of the exhaust note coming from the headers, high flow catted x-pipe, and NPP mufflers, so it's not really this loud in the car...

Note: I wasn't trying to make it sound like a manual through out the entire video, but it's obvious when I was trying...

 

no transmissions are failing without being tuned. I am talking about the actual transmissions failing, ie. broken parts, burned up shift clutches, etc.

the torque converter is a completely different part. it's like the difference between a clutch and the actual transmission in a manual application.

 

You don't have a clue. No one outside of GM knows how many stock, non-tuned, A8's have failed.

I know for a fact that this A8 failed(with a bunch of broken parts) in a 2015 Z06 with 7,000 miles and GM installed a new transmission under warranty. The car is 100% stock with no tune. Took the Chevrolet dealer 2 1/2 weeks to get the new transmission and install it.

See next posting for photo.

 

 

one example. here we go, the sample size expert strikes again. please post more one off examples seen only from your own corner of the room.

I can't wait to see your next "great point."

yes, of course, any mechanical part can fail, the known and widespread issue across GM, Cadillac, Chevy, etc with the A8 is the TCC, not the trans, in fact, there are almost no trans failures "compared to" A6, 700R4s, 4Lxx's, etc. which were breaking all the time with only 300-400 HP.

 

One example is all it takes to prove that you don't know what the hell you are talking about when you said..... "no transmissions are failing without being tuned. I am talking about the actual transmissions failing, ie. broken parts, burned up shift clutches, etc."

You don't have a clue as to how many transmissions have failed but you make posts that none have. You are clueless as to the scope of the problem.

If there is one failure, there could a dozen or there could be a hundred. And because you don't have a clue to how many have failed, your post was a complete fabrication but you posted it as fact. The fact is that you don't have a clue about what you are posting, and now you are trying to backtrack on your lie and you are trying to say I'm the one making **** up.

I can prove that there has been a A8 transmission failure(with broken parts) in a Z06. I posted up proof with a photo. Now you prove that there hasn't been a single A8 transmission failure, to back up your lie that it's only a torque convertor problem.

As for other A8 failures, I can state as a fact that a good friend and neighbor is on his third C7(all Z51's), because the transmissions failed on the first two and GM(and Reliable Chevrolet) replaced the transmissions(notice that I said the transmissions were replaced, not just the torque convertors). The only thing was that he wasn't present when the dealer pulled the transmissions so he wasn't able to take a photo of the failed transmissions. Now, my other friend, with the Z06, was there when the dealer's tech dropped the pan on the failed transmission and he took a photo, that I posted of all the broken parts.

I can also state as fact that a third friend had his A8 that failed, but a new control module corrected the problem and a complete transmission replacement wasn't necessary. The torque convertor was not the failed component as you want everyone to believe that the torque convertor is the problem and that there have been no transmissions that have failed.

I can also state as fact that I have several friends that have not had their 100% stock(ie: not tuned) A8 C7's transmissions(or torque convertors) fail(both Base , Z51 and Z06) but I don't get on the forum stating lies that all A8 transmissions are good and it is only torque convertors that have failed.

I can also state as 100% fact, that none of my friends with A8 transmission failures had a "tune". They were 100% stock and GM replaced the transmissions under warranty(they would not have if the car's had been "tuned"). Again, you don't have a clue.

 

you realize you have issues right? didn't read your post, btw, too much anger. go take your pill and come back when your body absorbs it.

 

At least I don't stick my head in the sand when confronted with facts, as you do. Maybe you should read my posts(as I'm certain you did, even though you claim you didn't) and learn something. If anyone needs to take a "pill' it is you. You need to take a "truth pill".

The fact is that you can't back up your asinine post that NO A8 transmissions have failed, but only their torque convertors.

That proves you know nothing, but are a big wind bag, throwing out crap that you no nothing about. Throwing out your "facts" about other transmissions(A6, 700R4s, 4Lxx's, etc" you posted isn't proof of anything as we are discussing(except for you who has your head in the sand) the A8 transmission.