the ZF Lurch in the Audi S6

A6 All/ S6 All
#1

There seems to be a common problem with the Audi S6 (and many other cars using the ZF 6hp26 and 6hp26a transmission). It has been called the ZF Lurch, and is described in the following two sceanarios:

[i][b]Variant 1 : The Lurch we experience occurs when you bring the car to a halt in a smooth manner by braking very gently and letting the car come very smoothly to rest. Just before the car has come to a complete rest a little lurch like somebody has gently nudged the car occurs. It feels like a gear is being engaged or disengaged just before coming to rest. This can vary in intensity from a very slight nudge to a powerful jump that rocks the car.

Variant 2 : In addition, when you slow very gently to a creeping halt without actually stopping and then gently try to accelerate - there is a slight hesitation when the engine revs higher, then the gearbox engages the drive wheels with a jolt. This varies from a harsh jolt to snatchy.[/b][/i]

If you google “ZF lurch”, and there are entire websites dedicated to it http://www.thelurch.com/lurching_zf_transmission.htm (not a good sign, as there did not seem to be a clear resolution)

Looks like people are trying all kinds of things…TCU update, transmission oil flush using specific oils (e.g. ZF Lifeguard6 http://www.xoutpost.com/822704-post85.html), rebuilt valve body http://www.xoutpost.com/872353-post12.html, etc. Looks like we are going to have to start another thread for this problem. At least we arent alone on this one, as BMW and Jaguar seem to be effected too.

If you have this problem in your v10 S6, (or Audi A6), then please post here so we can track the issue, and work on solutions. We need to know the following:

  • What year and model is your car?
  • Does your car experience Variant 1, Variant 2, or both
  • Does it happen in certain conditions, and not in others (e.g. when driving when car is cold, when using sport mode, etc)
  • Has the dealer done any fixes for the issue? Have they worked?
  • Have you done any other updates or changes that resolved (partially or fully) the issue?
  • Any other pertinent details
#2

reserved

#3

reserved

#4

reserved

#5

Audi S6 v10 2007…

Torque qonverter on low rews and idle make scratchy noise, like metal to meta, mechanic told me that this is reason why some time engine is rough, jumping with revs and shaking car. Firs owner newer change oil and filter in gear box, after 7 years, still was there original filter with date on it, and oil was like old engine oil. Mechanic tol me that oil in gearbox must be changed once at year, even if you did 5 miles per year.
Im not going to Audi dealer’s service, don’t have trust anymore because i have bad experience with another car…

My S6 Full build from start till now
#6

Hmm not sure if this applies but one day in traffic on the highway i let off the brake touched the gas the car delayed a few second then the transmission engaged and made a grinding noise and the car kicked forward, scared the shit outta me, should i be worried

#7

Ive had my transmission replaced under warranty because of the ZF lurch… so if you have warranty complain enough and they’ll replace it. I had both engine and tranmission replaced under aftermarket Fidelity warranty… after that they dropped me though because of the cost of the entire replacement…35k :o OUCH

I had done research and at first i assumed it was the TCU and bad solder in the TCU accompanied with heat from the engine causing the TCU to fail. i had horrible issues with my tranny some call it the lurch some call it the clunk… 1-2 downshift and stopping and 4-5 downshift … hesitation and clunking. Literally would feel as though i almost got rear ended.

#8

The BMW guys mentioned valve body rebuilds in one of your links. Back when we were troubleshooting an issue with the 5HP24 trans I found some helpful literature from Sonnax. Anyway I checked their site out for the 6HPxx and noticed critical wear items that are related to various regulator valves which fall into some of your symptoms. I haven’t review any of the Audi literature so it may be a repeat, but hope it helps in some way:

Valve Body & Mechatronic
http://www.sonnax.com/pdfs/12-Valve-Body-and-Mechatronic-Service-ZF6HP19-26-Aisin-AW-TR-60SN-09D

Solenoid
http://www.sonnax.com/articles/233-Flow-Control-How-Solenoid-Design-Influences-Clutch-Circuits

Direct pdf link (Vavle Body & Mechatronic):

http://s3.amazonaws.com/sonnax-dev/uploads/pdf/pdf/12/2011_Presentation_AutoChoice.pdf

#9

2008 Audi S6. 50k miles.

I experience Variant 1 in drive and Variant 2 in sport.

Temperature, etc seem to have no effect.

Dealer says car is ‘normal’ and made no fix. I even had the service manager drive the car for a day.

An independent Audi specialist recognized the problem, indicated ‘someone’ was working on it. Made no changes.

Nothing close to resolution.

Variant 2 in S can be VIOLENT. I do not use the S mode for this reason. I fear breaking something

#10

2007 S6
Experiences both variants, but Variant 1 is negligible, never really bothered me.

Variant 2 can be quite violent if several different factors align just right. Namely, when coming to a near-stop (2-3mph), and pushing the gas pedal before the transmission is done engaging 1st gear. Oddly, about half the time it happens smoothly, the other half of the time I get a violent lurch. Problem only occurs in Sport mode, no problems with A or M. Doesn’t seem to be affected by temperature.

I haven’t tried any fixes yet. I simply take it out of Sport mode when I’m doing stop-and-go driving, or I make sure to come to a complete stop every time. As the problem only exists in S mode for me, I had assumed it was a TCU issue, but I don’t really want to waste my time and money taking it to Audi, so I’ve just been waiting for a TCU tune to hopefully be available someday.

#11

I can’t figure out how to edit a post… I wanted to clarify that Variant 1 only occurs in Sport mode as well. Tranny runs perfectly fine in A and M modes. I honestly only use Sport mode once in a while, both for the lurch problem, as well as the fact that sometimes it seems like it holds a gear for way too long… ie, when I go full throttle up to 60mph, and let off the gas, the car stays in 2nd gear at like 6k rpm indefinitely until I gently tap the throttle again. Maybe it’s supposed to do that? Could be, but it doesn’t really fit my driving style so I don’t use it much when driving fast on highways and such.

#12

^^ you’ll be able to edit when you reach 150 posts.

#13

I don’t know if this helps but it’s not an issue on the 6hp19 transmission. I believe you guys are the 6hp28…

#14

Though this is an easy Google, I’ll post it here for clarity (no offence intended, Mr. Incredible :slight_smile: ).

Only the 4F S6 & RS6 have the 6HP26A. None of the A6s have the same transmission.

The 6HP26 is RWD, and the 6HP26A is AWD.

Here’s a list of the cars you can find each variant in:

http://en.wikipedia.org/wiki/ZF_6HP26_transmission

#15

Great info here guys. I can tell by the number of responses, these issues are going to be a lot more common than I originally had guessed.

The more people posting first hand experiences, and providing the key details as I requested in the first post, the more data we will have to recognize patterns and come up with solutions.

I haven’t talked to the guys at the shop about this yet, but I think it is pretty safe to assume that my car will be used as a case study to try and figure out all the things that are causing these issues, and come up with solutions for them.

Lots of great info around the web, mostly concerning the 6hp26. Symptoms are pretty much identical.

Keep posting the first hand experiences!

Thanks!

#16

It is so neat to see that others are experiencing the exact same thing. I get both versions but obviously version 2 is more shocking. And I have learned to ‘feel’ the gas pedal when I drive around in S mode at low speeds (I cannot stop doing it because I like to roll down my windows and hear the engine growl). I can tell when there is no catch and a big LURCH is coming. I swear the problem gets better after a recent service then slowly creeps back in.

Is it insane to think that? I remember reading that the computer ‘learns’ our driving style as time goes on. Is this just mumbo-jumbo from Audi? Maybe it is ‘learning’ and screwing up the change back into first gear at low speeds.

#17

I can definitely say I’ve experienced variant #2 on my '07 S6. When I first got the car I it happened a few times before I noticed that it only happens when coming to a rolling stop before accelerating again. It seems to me that the transmission hunts for too long when shifting from 2nd to 1st when you are rolling to a stop and if you start accelerating while it’s “hunting” it revs the motor then slams it into 1st.

I’ve only ever had this happen in manual mode when I don’t downshift myself and instead let the car decide when coming to a stop. I almost always drive in manual mode though and only occasionally use “D” so I can’t speak to the issue in “S” mode. I can say that I’ve never experienced either variant in “D” mode though.

The only thing I’ve ever done to the tranny was change the filter and fluid @ 65k.

#18

Do a google on ZF Transmission Lurch and read all the comments from Jaguar and BMW owners. We are not alone!!

#19

Paul did you say that so far the software update fixed your issue.

#20

Would any of you suspect that the newer C6s (2010-2011) are less likely to have this issue?