Most members here with the ZF transmissions are well-versed on "the lurch", although not all of us have experienced it. Thankfully, our S-Type remains lurch-free thus far.

I wonder what percentage of the lurch problems are due to nothing more than an underfill of ZF transmission fluid at the factory. This stuff is very costly and I'm sure that Jaguar (and any other manufacturer using ZF transmissions) would rather err on the low side as opposed to overfilling. In many modern, complex transmissions, being short by as little as 8 ounces of fluid can cause very noticeable shifting problems. I discovered this in our previous 2000 Lexus RX300 AWD. Learning that it had an inherently weak transmission design, I changed that fluid every 30,000 miles as an extra measure of protection. Rather than run the risk of overfilling, I added that last quart very sparingly. I found that if I left it short by even half a bottle of fluid, harsh shifting would be the result.

It is criminal for the ZF transmission not to have a dipstick. Not knowing how much fluid is truly loaded into all of our cars' transmissions puts us at a huge disadvantage from a proper maintenance perspective. Any basic fluid in a vehicle should be easily measureable and monitored by the owner. We can't do that with our ZF fluid, and it makes me wonder how many of us are driving around underfilled....

 

I totally agree. The first thing I did when I got my car home from the dealer was check the oil , coolant, brake fluid and then the search for the trans. dipstick with no luck. I thought I was missing something. My car has always had minor shifting issues. The dealer claimed that they added more fluid to try to resolve them but no luck. I'm skeptical if they did anything. My big problem is that my car downshifts very late even sometimes going into 1st after the car has stopped or at least right before stopping causing a surge or lurch as its known. Even after the torque converter was replaced, same issues but less severe.

 

Hi badmojo,

Have you tried the Sportmode? I noticed when I did, the upshifts and downshifts happen at about 500 rpm higher than Normal mode. Also, did you have the J004 re-flash done? When I had this done to my car, I noticed the shift points were about 200 rpm higher than before.

Mike

 

badmojo - you'd hope they would have filled yours correctly prior to and after your TC was replaced. It's unlikely it would have been underfilled twice. But have you had the reflash of both TCM and PCM followed by very careful driving (including not using sport mode etc) as described in the TSB which addresses the lurch?

In case it's not been done while you've owned the car, about all you can assume is that it's not been done. I suppose

J004 is basically emissions-related, I understand, though the actual TSB doesn't appear to be freely available.

 

It's all been done several times TCM, ECM, software updates, not using the sport mode after re flash. It is definitely better but I feel that it is still a little off. Even after I do a hard reset myself it feels great for a few days but slowly it starts to go back.
I have also tried the sport mode and it does feel better. I'm going to try it again for a while and see if it helps. One dealer also said that 1 quart overfill is sometimes recommended to resolve these issues.The service order says that only the TC was drained and the new one filled not the whole tranny. So it could still be low.
Thanks.

 

Isn't the only realistic way to fill the TC to use the fill port on the side of the tranny?

 

The TC's that I've filled have a plug on them for filling and draining separately. If you put an empty TC in a car and started it and the fluid filled it the trans would be low on fluid. The TC holds a fair amount of juice!

 

I've had no problems since my transmission had updated software installed and was re-flashed under a recall notice in April.

Eric

 

I have found that in the warmer weather that my transmission shifts more smoothly. In the colder weather (below 60 degrees in FL), the car exhibits a slight lurch and delayed downshifts. I don't worry about it too much. Like the steering wheel noise, I write it off as a Jaguar characteristic.

On the other hand, I think it's criminal that the car does not have a dipstick for the transmission. I wonder if we can get someone with a machine shop to fabricate one and sell it to us. Of course, then there'd be the issue of installing it...

 

I'm new to all of this and have little to no mechanical knowledge. I read through thelurch on the internet and my car has the type 1 lurch, so can someone provide a beginers guide, thanks!

I take it that there is no definitive cure to the lurch?

Is it something that needs to be fixed, or does it appear to be a characteristic that will not affect the long term life of the transmission?

Is there a best way to try and deal with the lurch ie the 'flash' thingy or changing the transmission fluid regularly?

 

I think it will help to understand the Lurch is a result of the adaptive programming of the 6 speed ZF transmission. The adaptive programming drifts over time for different reasons. It keeps monitoring how you drive in an attempt to customize the shifts to your style of driving. But if you drive aggressive one day and like an old lady a different day the transmission is always changing the program!

I notice this very much when the car has two drivers. So the Lurch does not harm the transmission but is a drivability problem. Some people claim they have never got rid of it. My 2005 STR had it until the reprogramming. I now have a slight 1st to 2nd clunk when rolling to a stop but only sometimes and it is very mild. If I was not looking for it I probably would not notice it.

I am very interested in checking the fluid level and condition after reading other peoples experiences. It just is such a pain to do it. You can't really verify that the dealer did it correctly either!! Not a fan of no dipstick but this is now very common. My wife's 2003 Lincoln LS has a completely different Ford 5 speed automatic and it does not have a dipstick either.
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Thanks for that tbird6. So, because I have just got the car the lurch could have developed just for me? I am sure it did not start until I had had it for a few days. My driving style has not been different since I got it. So how long until it 'learns' my style?

EDIT - I have just told the wife about this thread and her comment was 'my driving style must be like the last owner as it does not lurch for me'. Or is she trying to claim she is a better driver than I ?!

 

tbird6 - as it afflicts BMWs etc it's got all the hallmarks of a software bug which would appear to be semi-fixed but not actually fixed. As the semi-fix is to reflash PCM & TCM it's likely Jag (and BMW etc) got together with ZF to tweak the CAN messages sent between PCM & TCM. Maybe they'll one day develop a proper fix but as so much time has gone by it looks unlikely.

Meanwhile, the lurch (any of 'em!) must be stressing something in the drivetrain

 

It affects any car that uses this 6 speed ZF (Jaguar, Audi, BMW, MB, Ford). The transmission was designed this way on purpose. It's not a bug at all. The transmission thinks it's doing the right thing by changing the shift patterns. I would do a hard reset by removing the battery cable for 30 minutes. Then follow this from the Jaguar TSB: Note: They don't list the STR?

Carry out the adaptation drive cycle road test:
Note: This process must be carried out in normal mode (not sports mode). On a flat road, the transmission fluid temperature must be above 60° C (140° f) and below 100° C (212° f) (vehicle at normal operating temperature will ensure that the transmission fluid temperature is above 60° C (140° f)).
9. Accelerate from rest with light throttle (do not exceed the upper rev limit in appendix 1). 1-2, 2-3, 3-4 shifts must occur with engine speed between the following limits:.
• 3.0L VIN ALL 1800 - 2000 rpm
• 4.2L N/A Prior VIN M96321 1450 - 1600 rpm
• 4.2L N/A From VIN M963221550 - 1700 rpm

10. Continue to accelerate gently to 50 mph (80 km/h) so that transmission shifts into 5th gear.
11. Go into overrun and let the transmission shift down into 4th gear without braking.
12. Brake gently to a standstill and hold footbrake on for at least 15 seconds.
13. This process should be carried out at least five times.


See if this helps. The programming drifts over time so this might only be a temporary fix??
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It also does not list the diesel. I am happy now I know it is not my driving nor a problem with the brakes.

 

tbird6 - I know it does it on purpose. Adapting to driving patterns doesn't sound daft. I've not suggested that's a bug.

However, drifting over time sounds like a bug. It should get better not worse as time goes by. (At most you'd expect a little "hunting" as per other control systems.)

The various lurches definitely sound like bugs - quite serious ones I'd say. Who on earth wants a thump in the back or a jerk when setting off and when would those be desirable to the various mechanical things suffering the jolts concerned? Are you saying those ARE deliberate and desirable?

 

But the transmission does not know it's a thump or a jerk. Only the driver knows that and it depends on whom the driver is. You will see a common thread about this lurch. That is some people have it bad and other people claim to never have felt it. The adaptive programming is a two edge sword with some strong positives but some additional negatives. In other words there is no "Correct" programming. It is only correct when that specific driver says it's correct.
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Lots of people in lots of car makes can feel the lurch. When the ZF engineer experienced the lurch he could feel it. I reckon an accelerometer or the like will also detect it. Probably the PCM can detect it, just as it can detect very minor jerks in the drivetrain such as those caused by misfires. The tranny may not have the required sensor although given the nature of this thing you'd sure expect it to have been designed to detect and avoid it. But it could be told by the PCM. Heck, to cure such a fault they could fit a sensor in the tranny! (The STR has about 4 already.)

It simply cannot be correct to cause the lurches. Surely it would be better to have a software setting that did no adaptation at all (if need be) but also didn't lurch. Other autoboxes in my experience never lurch. The ZF is supposed to be better than them.

There again, they all had dipsticks. Bring back the dipstick. And they used oil that was a reasonable price. Bring back the sane oil.

I note there are different versions of the ZF 6HP26. I wonder if the later ones have been changed so they don't lurch?

 

There are different versions as well as different torque capacities. This is a chart from a ZF document. It is NOT from any car manufacturer. You can see it will handle more torque that the STR with 400 ft-lb. I don't know what is the highest powered car the transmission is used in but it's more than any Jaguar!

ZF considers this a line or series of gear boxes and uses this label: 6HP26X / 6HP28X

No the PCM cannot feel it. That is my entire point. It's only a problem when a person decides it's lurching. How much is too much? Well again it depends on the person.






Input Torque
1 Gear
2 Gear
3 Gear
4 Gear
5 Gear
6 Gear
Rev Gear
Weight (incl. oil)
326 ftlbs to 444 ftlbs (model specific)
4.17
2.34
1.52
1.14
0.87
0.69
3.40
~196 lbs.

 

I don't think the torque it can (or can't) handle is relevant.

Unless the TC is unlocked, the PCM could feel the lurch, but no matter.

Existing autoboxes were and are designed to be smooth to some spec (specification). The ZF could have been designed to be the same. It's not. It lurches. Easily verified using pretty cheap sensors and let's be honest ZF engineers aren't restricted to those during the design and development phase. Agree so far?

They could have designed this out. They could have retrofitted a non-lurching design. (That's lurching as detectable by a real machine set to a threshold along the lines of existing specs mentioned above.) They haven't. Probably a cost issue.