I've been trying to find similar information on the mechatronic and what is / isn't worth doing to them. The ZF manual for how to dismantle the transmission is pretty easy to find but there is next to nothing about the mechatronic.

The instructions for the Sonnax kit has a little info but, before today, I had not found any document that really described how the thing actually worked.

I finally found the English translation on a Japanese website of all places. It is available for free, but only through a Flash online reader so I spent about an hour this morning extracting all the pages.

Quality is not the greatest, but it has a lot of interesting/useful information in there. I have not thoroughly read it yet myself but thought I would share.

 

This is information that I have on my page that may help.

Link http://www.jagrepair.com/images/Auto...%20Control.pdf

 

Hmm, just found this. http://www.jagrepair.com/images/TSB/...wnshifting.pdf

 

And it was on my page. Fancy that! I would still check the trans mount.

 

Sorry Gus, have been to your site many times, and I find it very good.

 

I would phone or e-mail Klaus Malenke at The CTSC in California and have an in-depth discussion regarding the Mechatronic system with him. Klaus worked for ZF for more than 30 years and has always been very forthright and honest with us forum members who have communicated with him. I know he is difficult to reach by phone but I did manage to get him on the line a couple of times in June/July 2013 just before I ordered his 6HP26 refresh kit. Go to The CTSC - ZF Parts and try to get ahold of Klaus through his website....

 

Last summer, when my annoyance level had gotten pretty high, I called ZF tech support (800 660 2269) to see what I could learn. You can tell they keep these guys on a pretty short leash in terms of admitting to any weak points, but my rep did seem to be trying to help.

Takeaways: before looking into anything mechanical ...

- Assure that the fluid level is correct. Do this even if there is no indication of leakage. (Uh, thanks for the dipstick, guys.)

- Do the reflash, if not done already. He explained an interplay between the software (reflash) and the adaptations ... With early software, the adaptations can drift into states that can produce harsh shifting. Later software somehow manages this drift better to avoid trouble. (Of course this is not to say that all software was not perfect in every way. ... OK, noted.)

FWIW.

Also, it's worth remembering that the 2nd-to-1st thunk is not peculiar to Jaguar. Lots of Beemer pilots complain of it.

 

Dennis,

It's good to know that you spoke with ZF tech support as recently as last summer. I remember speaking with them back in 2010 and 2011 when I was doing my initial research on when to do a ZF drain-and-fill on my S-Type and what potential alternate ATFs I could consider. I spoke with Steve Jaffe at ZF on several occasions and always felt that he was shooting me straight with the information he provided....

I finally did that S-Type drain-and-fill last November at just over 85,000 miles. I went with Mercon SP ATF because it meets the required Shell M1375.4 specs, Ford used it in the 2005-2008 Lincoln Navigators running our exact same ZF 6HP26 transmission, and I can buy it at any local Ford dealership for about seven bucks a quart. Mercon SP has performed perfectly in my S-Type and I will be using it for any future ZF 6HP26 drain-and-fills that I do....

 

Steve Jaffe Is a straight shooter and a great guy.

 

Thanks everyone, some really good info here.
I think I will try Klaus, see what he has to say about the valve body, if the upgraded one's are a preventative measure for future internal failures.

Regarding the comment about the 2 to 1 downshift clunk not being a Jaguar exclusive feature: I also found a lot if info in some BMW forums where they have this issue. Interestingly, it seems that BMW has a TSB for this. It basically says for pre 2003 MY cars, re-flash the TCU and inspect the flex disc (Jurid in Jaguar language) and on 2003 and later MY cars, inspect and replace the Jurid is the only fix. This suggests to me that some of the issue is software related, and another cause is the flex coupler/jurid worn out. What I don't see is where Jaguar owners have had to replace the jurid very often, it seems rare. Anyhow, people of the BMW forums seem to have excellent success with the coupler replacement.

 

I would still get the car on a lift to see if you can identify any abnormalities. Re-programing has helped many but that is done by Jaguar and it comes at a cost.

Relevant or not I had a 4-Runner that would thump as I was stopping and after several trips to Toyota they replaced the front driveshaft (split shaft) and it fixed the problem. We found that when stopping the shaft would elongate and get stuck for a moment then release causing the thump that was once thought to be a downshift issue.

 

My PC is dead, so I can't look up in JTIS the part number, but I suspect there isn't one. I am looking for the part number for the Jurid, or flex disc for my 2004 XK8. I have read conflicting information on the web, this forum, and parts suppliers. Some say the Jurid is not a replacaeable part for the 2004 XK8, and that jaguar only sells a complete drive shaft assy. But, I have found part number CBC8996, which is used on many different model Jaguars, including the XK8, however, for the XK8 only up to 2002. Yet again, I read a jaguar forum member post with a 2007 XK who was told the same thing by jaguar: it is not a replaceable part, but he bought the Jurid for an xtype, which was an exact match.

Does anyone here really know what part number fits in the 2004 XK8? Has anyone replaced one?

I purchased Euro brand Jurid chc8996 which I plan to have installed at an indi, as I can't get access to it on jack stands. Just would like some confirmation before I pay someone.
Thx

 

Well, the Euro CBC8996 is not a match, bolt pattern is slightly off. Going to the jaguar dealer to try to match one.

 

Just curious, how do you know that there's something wrong with your existing coupling?

 

That is an excelelent question. Short answer is, I dont (or didn't).

However, there is a TSB for the S-Type (I think that is the model, but don't have it in front of me) that said, depending on vin range, to resolved the 2-1 downshift clunk, either reflash the TCU, and or replace the Jurid. I figured that for fairly cheap money, I could replace the Jurid that has just over 100k miles on it now, and I would know it either was this, or not, causing the clunk. Either way, I would have replaced the old Jurid never to worry about that part going bad again. That is why I went down this path.

As it turns out, there is nothing obviously wrong with my Jurid. I have seen photos of some very worn flexdiscs, and mine looked nothing like those, it looked to have no wear that I could see. Because my aftermarket replacement was not the correct part, and no where can I definitively source a replacement, back in went the old one.

I then went to my local Jaguar dealer, and saw my friendly service advisor, explained, my issue and she said lets go talk to your technician. We talked about the issue, and he said almost always the issue is resolved with a reflash of the TCU. I reminded him he reflashed it at about 65k miles for a harsh up shift 1-2, and he said that it is possible that the TPS was sending incorrect info to the ECU and TCU for years, resulting in the TCU learning incorrectly, and that with the new Throttle Body on now (I just replaced it a few thousand miles or so ago due to a TPS error code), he thinks a reflash is in order. This time, he will go through a "coded" reflash. He tried to explain what that means, but as I understood, it is a more in depth reflash, where they hook up the car to their system, call Jaguar with my VIN, and get special code for the reflash. He said that is done only after a normal reflash doesn't resolve an issue. I am guessing this really means completely re-programming the TCU, not just a software update and adaptation reset, but all new software download. Just guessing. This is scheduled for Wednesday of this week.

 

A little more info about the throttle body and TPS statement in my previous post.

I went through the pains of a driveability problem last summer and fall, but no error codes until finally one day I got a RP and code. It was a bad throttle body, related to the TPS. This went on for a bit until finally it would not even run without immediately throwing the code and going into limp mode. I replaced the throttle body. Car ran great after this. One thing that surprised me was that after the new TB was in, when driving around town and coming to a stop, as I was "coasting", it acted as if I was coasting with the clutch pushed in. Of course there is no clutch, but this was the sensation. So different from what I was used to for more than 40k miles, it was somewhat startling, I would briefly panic thinking the engine stalled. It never did this before the throttle body was replaced. Don't be mistaken though,it still would clunk 2-1. I surmise that the old TPS was either not adjusted properly, never letting the TCU know that there was no throttle applied. So, in my previous post, the technician speculates that perhaps the TCU adaptation process and years of driving like this, could result in incorrect learning.

 

My experience with the reflash vs jerky 2-1 downshift is that the reflash by itself didn't change anything.

I had to also reset the TCM adaptations and go through the SDD prompted drive cycle. After that, the issue was much much better.

 

Thank you, yes, they are going to do the adaptations and SDD drive cycle too, I just didn't spcify that previously.

And "coded access" is the term the tech used to explain the TCU reflash process they will use. Apparently, coded access is different than a regular reflash.

 

Dealership completed the coded access TCU reflash, and went through the drive cycle process as required. It did not resolve the clunk 2-1 downshift. It did make a noticable difference in overall shift quality though, so benefit there.

I now believe the clunk is being caused by transmission output flange, either being worn, or, I need the updated part, which is supposed to correct this issue on the XJ per Jaguar TSB XJ307-2. I have not been able to find a similar TSB that applies to the XK8/R, and I understand that it is possible that our cars have the updated flange already (probably no way to really know), yet, the flange is under $100, and labor only a couple of hours, seems like a resonable chance to take getting it replaced. It could be simply a worn flange as well. I may try to find someone to replace the flange - I don't think the dealer is interested in replacing it.

Date of issue 06/03 Amended 06/04 Bulletin Number XJ307-02 Page 1 of 2

DATE

Amended 06/04

SERVICE

TECHNICAL BULLETIN

Driveline Clunk/Knock When Downshifting –
ZF 6HP26 Automatic Transmission –
Repair Procedure

2004 MY
XJ range
Refer to text
MODEL
VIN

XJ range

NOTE: THE INFORMATION IN TECHNICAL BULLETINS IS INTENDED FOR USE BY TRAINED, PROFESSIONAL TECHNICIANS
WITH THE KNOWLEDGE, TOOLS, AND EQUIPMENT TO DO THE JOB PROPERLY AND SAFELY. IT INFORMS
THESE TECHNICIANS OF CONDITIONS THAT MAY OCCUR ON SOME VEHICLES, OR PROVIDES INFORMATION THAT
COULD ASSIST IN PROPER VEHICLE SERVICE. THE PROCEDURES SHOULD NOT BE PERFORMED BY “DO-ITYOURSELFERS.”
DO NOT ASSUME THAT A CONDITION DESCRIBED AFFECTS YOUR CAR. CONTACT A JAGUAR
RETAILER TO DETERMINE WHETHER THE BULLETIN APPLIES TO YOUR VEHICLE.

Issue:

Owners of some 2004 MYXJ range vehicles, equipped with the ZF 6HP26 automatic
transmission, may complain of a driveline clunk/knock when changing from reverse to
drive, or while downshifting from fifth to fourth or second to first when the vehicle is
slowing.

A modified transmission output shaft flange and seal has been released to
address this concern.
Action:

in case of a verified customer complaint of the above condition, follow the workshop
procedure outlined below.
WORKSHOP PROCEDURE

1. Install a new automatic transmission extension housing seal and output
flange (see Workshop Manual, section: 307-01, SRO 44.20.18).
Note: When removing the transmission output shaft flange, if an
O-ring is installed behind the nut, the O-ring should be removed
and discarded. It is only required for testing during initial build of
the transmission and a replacement is not required.

Remove and destroy Bulletin XJ307-02, dated 06/03.
Replace with this Bulletin.
Revisions are marked with a bar and in

MODEL YEAR VIN

XJR 2004 G00442 - G23484
XJ 2004 G00442 - G22915
Page 2 of 2 Bulletin Number XJ307-02 Date of issue 06/03 Amended 06/04

Parts Information:

DESCRIPTION PART NUMBER QTY
Extension housing seal C2C 6719 1
Locknut C2C 6725 1
Output shaft flange C2C 25737 1

Warranty Information:

Warranty claims should be submitted quoting the information found in the table below.
This will result in payment of the stated time and, where applicable parts/miscellaneous
expense codes as listed.

 

It has been a while since I posted on this subject, so here we go.


My initial post was sort of a 2 part question: are some of the symptoms we experience with our 6hp26 transmissions nuisance, or damaging; and, what can be done to resolve these? See my first post for more detail. I heard from several forum members with great suggestions and information. I never connected with Klaus as was suggested. I went to the website, but found no email or phone info. So then I searched the internet and found some good info about our 6 speeds, but never any smoking guns. In contrast, there was plenty about the zf 5 speed. This leads me to believe what I have read, and suspected, these are fairly solid units, and have no real specific weak point. That's half of my question. The other half was specifically about what I believe now to be nuisance issues. My main issue that I have been obsessed with for several months is the driveline clunk when coming to a stop at the 2-1 downshift. This really has been driving me crazy. After finding the TSB for the x-type and XJ mentioned in my just prior post, I asked the dealership about this, and they said they didn't believe this to be the issue of my clunking on the XK8. Yet, they couldn't say why the XK, with the same transmission, was not also included in the TSB. They would not install the new output flange and seal, even though I requested it and of course would pay for it. So, I bought the parts and had Sun Tire install the flange, seal, and new a new transmission mount. Parts were $160, labor $90. Clunking GONE! I am so happy. What a difference.


Thanks to everyone for your support and suggestions.
Steve