Jon8138

I have a 2012 A6 3.0T currently at stage 1+ and about 430hp. Trans is a ZF 8 speed. Just bought the car a few weeks ago and did not notice a stumble or studder at low RPM on the test drive. Now that I've been driving the car I've noticed that in either 2nd or 3rd gear there is a studder while accelerating from 1500k to 2k. RPMs will rise to about 2k in 2nd gear and then drop back down to 1800k. Feels like a false shift. Once it slips back down everything is normal again and you can accelerate as hard as needed. Almost feels like the torque converter studders until it starts to lock again. If you keep the RPMs above 2k everything is fine, no studder. If you start out in first it seems to just power through and everything seems fine as rpms are above 2k on the shift to 2nd. This happens in drive, sport, or tiptronic. Anyone ever have this issue? Def seems like it's trans or driveline related, not motor mounts or misfires. Car runs great besides that and is very fast and responsive. No codes or faults in VCDS. Just would like to see if anyone has ever felt this studder In their zf8 at low rpms only and what the issue is?

John Simcox

It is possible the transmission needs a fluid change. Audi suggest that the fluid does not need changing ever, however ZF themselves recommend a change every (I think, but no doubt someone will confirm) 80k miles, so it may never have been done. You don't say how many miles your car has done but after 12 years I am guessing it is probably at at least 80k miles

kronikfumes

Yeah I also experience this. It is most noticeable in stop and go/slow moving traffic. I also have no other transmission issues. Have you tried doing a transmission adaption reset before? That made it go away for me for a time, but I think the “learning” aspect of the transmission paired with stop and go/slow moving traffic made it come back again over time.

Currently at 108k miles and plan to have get my second trans fluid service done (last done at 60k miles). I have had a TCU tune since like 95k so the interval is recommended to be closer to 35-40k miles). I also would suggest looking into a transmission fluid change.

Jon8138

Thank you. Car has 105k on it now. I was told the trans was serviced at 80k but I have no records. A fluid change and rans adaption are
on my list of things to do. Car had a stage 1 TCU tune as well but I have flashed back to stock which seems to have slightly helped. I've also heard there is an upgraded trans mount that can be installed that has solved some of the zf8 trans studders. I know this trans is kind of known for this but I still feel something isn't working as it should. Just wanted to see if others have felt this issue and what exactly has solved it. I will report back once I complete a Trans service and adaptation. Hopefully I'll find some time to do both soon enough!

Jon8138

Im going to try the trans adaption this weekend if I can get me VCDS to accept a new VIN. I also had a 034 motorsports stage 1 TCU tune but flashed it back to stock. It did help alittle since the shifts arent as hard now but something is still off. It really shouldn't rise in RPMs, drop back down, rise again and then shift. If you press down on the pedal hard below 2k it will bring the rpms up, drop down and catch itself and then accelerate normal. Maybe fluid level is off or just old, no way to really know until I service it. I was told it was serviced at 80k and now its at 105k but I have no actual records. I've been trying to make sure I start out in 1st gear instead of 2nd from a stop so I miss that 1500k-2000k problem area. Car feels great beyond this issue and I'm sure I'll figure it out the more I play around with it. My one fear is the trans Is actually damaged but I don't think it would shift as well as it does th rest of the time.

MyDimeIsUp

Following. I've had this in both my old tranny as well as my new one. My old one had about 113k on the clock, no history of fluid changes at all. Once I was tuned on 034 Stage 1 ECU and TCU and would launch control/AMAX, it would shift from 1st to 2nd, and then once I reached red line it wouldn't shift into 3rd until I let off the gas. I swapped in a tranny from a 62k-mile A7 (right at that fluid change sweet spot). Once we had the 62k mile tranny in, we swapped my TCU from the old valve body to the new one to avoid component protection coding, put a new filter in, and actually pumped just over 6qts (probably since all the fluid had drained out of the torque converter and other nooks and crannies of the tranny).

I've had no issues with launch control since, but I still have that exact same problem with stop & go, along with accelerating slowly from a stop. I was able to log with OBDeleven and the torque converter is slipping for a long time, at which point the TC locks up and the revs will drop from 2k to 1,800 RPM. If I'm in manual mode and do a rolling stop slowly, I can sometimes even shift from 2nd to 3rd while the TC is still slipping, and the RPMS will drop very little during the shift until the TC locks up again. It does this both stock as well as on my 034 tune, and with my old tranny as well as my new one.

I also have that exact same issue with accelerating slowly from a stop and have logged with OBDeleven and 034 when the TC decides to lock up almost immediately after accelerating. When shifting from 1st to 2nd not in manual mode, it feels like power is cut for a good 3/4 second (and feels almost like a manual transmission with the 3/4 delay between engagement of the next gear). What I found from data is that the engine retards timing between the shift so that explains the loss of power, but why is it taking 3/4 a second of timing retardation until 2nd gear actually engages. I'll have to record a video and save the data log. If I am in manual mode and do normal acceleration and shift myself when the TC locks up nicely, the gear change is much much faster, and doesn't feel like a little man is inside my transmission shifting slowly. Under medium acceleration, the TC sometimes lockups up quickly, other times I get that 2k to 1,800 RPM drop. When it locks up nicely, it is pretty snappy. Under hard acceleration the TC locks up almost immediately and gear changes are quick.

Really weird that my 113k tranny as well as my current 62k both have these exact same issues, both stock and 034 TCU tuned. Again I didn't swap the valve body from my 113k mile tranny, just the TCU to avoid component protection.

DanTheC7Man

Just wanted to add some info to this thread based on my experience so far. I have the exact same issue as described in the original post. My car now has 146k miles and the transmission has had that 2nd gear slip since I got it around 120k miles. I found no history of a transmission fluid change, so that's the first thing I did but it didn't seem to change anything. I also bought and installed the transmission and drivetrain mount inserts from Eurocode, but that also didn't solve the issue.

There are 2 things I still want to try at this point, which I haven't done yet. First, I want to do the adaptation but haven't gotten around to it, and also not sure how to do it yet. I'll eventually look it up, but if anyone knows how to perform the adaptation of the ZF8 or can send a link about it, I'd appreciate it. I'd prefer doing it in ODB11 if possible, but I also have VCDS if required. In addition, I also bought the "zip kit" from Sonnax that replaces some parts in the valve body that tend to wear out over time and cause fluid pressure loss.

MyDimeIsUp

The adaptation can be done in OBDeleven. I forget exactly what the name is, but if you go into the TCU and adaptations, there should be a standstill adaptation. Parking brake must be on, you must be in drive, and your foot must remain on the brake at all times until the adaptation is complete (Get comfy because your foot will get tired).

Honestly I doubt that'll fix the issue. When I swapped in my 62k tranny (torque converter and valve body included), the only thing swapped was the TCU. We obviously did a fluid drain and fill, with new filter, and adaptation. It fixed my launch control issues, but the torque converter slip still remains. I doubt an adaptation will fix it for you. I honestly think your best bet would be the Sonax valve body kit, but the standstill adaptation is free so it doesn't hurt to try! Adaptations will even out a final bit (nothing too noticeable besides shift patterns) after a couple days of driving, but I had no luck immediately after the adaptation finished nor a couple of days after.

If you get the Sonax kit I would love to hear how it goes for you. I've been meaning to do a vacuum test on my old valvebody but the tools are like $150 to properly test it.

DanTheC7Man

I appreciate the explanation about how to do the adaptation! I already have the Sonnax kit, it's just been collecting dust waiting for me to have time and motivation to do it. I think I'll do the adaptation before and after I use the zip kit and see what the difference is. I'll be sure to share my findings once I do.

I'm currently in the middle of engine work (doing timing chain tensioners...), but once that's over I plan to start working on the transmission. Hopefully, I'll have an update by the end of this month.

Valpo A7

Had a non Audi car a while ago that developed a shudder and the fluid change did not immediately clear it up. Had about 100k on the car but it cleared up a couple weeks after the fluid change. Did the next change at 150k and was gonna do it again at 200k miles but traded it for my old A7. Now the A7 had 234k miles on it when it was traded in and the fluid was never changed. Transmission was smooth as silk in that thing.

The ZF is very fore giving and will go a very long time on the Life Force juice or what ever it’s called. There is a thread in the A7 section where a guy did his first change at 192K miles and it’s running fine. An American domestic transmission tends to sludge at higher mileage when not changed and a fluid change can/will wipe out the sludge and screw your trans. The guy that changed his at 192K had talked with ZF engineers first who assured him it would not sludge and be safe to do.

Of course if you really want to know the shape of your fluid then pull a sample and send it in for analysis, I think it’s like $30 with Blackstone Labs