[cjperformance]

Have 2017 SS w/ A8. I don't get many opportunities to have the WOT 4-5 shift occur, so its hard to be extremely detailed, but I've noticed it seems much slower or "lazy" compared to the other shifts. Where the other lower shift points are pretty snappy, the 4-5 "drifts" from gear to gear quite a bit more.

Wondering if that is normal, or is indicating internal slippage. Anyone else notice this?

Is shift quality, shift speed, etc available in something like HP Tuners logging where I could get better data around this?

[arpad_m]

I'm not entirely sure there is a problem with your transmission. Fifth gear is very tall on the A8, it may very well just be that, as it simply takes longer to wind out fourth. This is one advantage of the A10, it has an extra gear with a ratio smack in the middle between the A8's fourth and fifth. (It also has a completely useless extra overdrive gear.)

See this post for gear ratio details, you'll see the difference when you compare the 8L90 to the 10L90.

[Trochoidal]

Originally Posted by cjperformance

Have 2017 SS w/ A8. I don't get many opportunities to have the WOT 4-5 shift occur, so its hard to be extremely detailed, but I've noticed it seems much slower or "lazy" compared to the other shifts. Where the other lower shift points are pretty snappy, the 4-5 "drifts" from gear to gear quite a bit more.

Wondering if that is normal, or is indicating internal slippage. Anyone else notice this?

Is shift quality, shift speed, etc available in something like HP Tuners logging where I could get better data around this?

You’re definitely not imagining the “lazy” shift from 4th to 5th. It’s there and I’ve heard it from other cars on the street, in videos as well as my car.

Cars with TCM tuned appear to lose the “laziness” when it’s done correctly.

I’m still dragging my feet on sending my TCM out. There are definitely other members on here that know what this is and can offer better input than me.

[cjperformance]

Thanks for the info. I just put on a procharger and am somewhat concerned about roasting the clutch packs. It had the same issue when it was still N/A too... the 4-5 shift occurs around 108 or so, so haven't had much opportunity to see if its about the same as before (indicating a solenoid-clutch-timing/tuning issue), or if it drags out even longer with the increased power (which to me would indicate slip).

I really envy the folks with the A10!

I'll keep poking around and see if I can find more info about how to tighten that up.

[wnta1ss]

While the 4-5 does have something of a gap, it should not feel THAT bad with a blower. What rpm are you reaching in 4th? Because centrifugal blowers like rpm, better to run in their happy place than to short shift. I did have a centri blower on an A8 car myself, so this opinion is based on my experience.

What size tires on the back (relates to the 108 in 4th comment)?

[cjperformance]

I have standard 245/40R20 front tire and a 275/35R20 rear tires.

Until I can get on a dyno or a track, it's not something that I can test thoroughly for safety and legality reasons

I think the takeaway is... it *might* be clutch slip, but others have noticed 4-5 shift anomalies, and so I should keep an eye on things and test further, or look into tuning the transmission.

It may just be that the trans need to re-learn clutch pack application speed at that vehicle speed too. I'll definitely post back if I learn anything useful. I've been looking into tuning in general so it's good research material. It's only at WOT, and only in 4-5. I dont get up to that speed often, so there isn't really much risk for trans damage under normal operating conditions.

I plan on getting to the track and/or dyno in the next few weeks.

[wnta1ss]

When you say "look into tuning the transmission" do you mean that no tuning has been done to the TCM yet?

[cjperformance]

Right, nothing tuned on transmission.

[wnta1ss]

Originally Posted by cjperformance

Right, nothing tuned on transmission.

Hmm, the trans tune is very important IMO. Yes, the 2017-2019 models are a pain in the ass with the send in the TCM for unlock procedure and the 4 credits needed.

[cjperformance]

Just following up on this. Never did anything to the trans, and the 4-5 shift is crispy now. Its been fine for quite a few months, probably shortly after my last post in this thread. I think it just needed a few more 4-5 shifts at WOT to learn what to do.

[KingLT1]

Common issue on untuned A8's when you start making some power. A friend of mine bought a SS this summer off a forum member that has a P1x and LT4 fuel system tuned by a popular name on this forum. The trans shifted like shit 4-5. Prior owner acted like he knew nothing about it. So I am guessing prior tuner didn't get a chance to fix the issue since it was a remote tune... Either way I fixed it.