zf6hp26 shifting 2-1

[Entwicklung34]

A wellllll discussed topic I know... however I thought a discussion about some recent findings might be useful...

Background: Since I bought the car (2004 3.0d x5 sport) it shifted harshly down from 2-1 when just about coming to a halt. Funnily enough it didn't do it on the test drives, but I wasn't aware of the issue then so didn't 'look' for it. Anyway, as time went on the g-box started to make more noticeable shifts and the 2-1 lurch was annoying me. It also seemed to be 'gear-braking' as I was slowing down coming to lights etc which I was worried about.

So, I took off all the covers etc under the car and discovered a leak from the 'sealing sleeve' at the back of the gbox.

Following this I recently changed out the transmission filter and refilled the approx 6litres of atf using oem bmw fluid. (While there I also changed the transfer case fluid and both diff fluids). Having put it all back together I test drove and the 2-1 shift was gone... for a while. Next mve was to reset the shift adaptations on the transmission with INPA... this initially made the shifting poor (I was really worried then!) but it improved over a few miles which was a relief!

The shifting was then back to my 'normal' but rid me of the 'gear-braking' which is good. After some more reading I tried the 30 second accelerator to the floor throttle reset. This made a fair difference to the shifting (someone may be able to tell me why) and the 2-1 thud on stopping was gone for a while which was amazing! However it has returned intermittently, probably in something like 90% of stops now.

What I find interesting is that the g-box CAN shift fine so the problem shouldn't be mechanical, but more of a communication/electrical sensor or timing issue... does this make sense to anybody else? Coupled with the suggested 'switch to sport mode when slowing down' that also works (as does using 'manual mode' and keeping it in gear 2 until stopped) this suggests a computer based solution. Yet, the more I read on the topic the more I see people paying out £££'s for the software update and not seeing an improvement.

Is there anything i'm missing here? I don't have the money for a new gearbox or a rebuild and to be honest it doesn't seem necessary when you put all the evidence together.
Does anybody here think it's worth trying a software upgrade based on their own experience? Can't buy into the 'this box just works like that' because no-one in their right mind would drive out of a showroom in a car this expensive operating like this. At the end of the day I can live with it jabbing me in the back at traffic lights, but i'm sure there's somebody out there who can shed a bit more light even on such a well-discussed topic... we'll I hope so anyway!!

Thoughts, experiences, suggestions most welcome.

[Entwicklung34]

Additional info: The lurch (2-1 downshift) seems to be much improved/not present when the car is cold, getting much worse when warmed up. I will be connecting INPA and checking gbox temp from cold and seeing what it reaches... i'll report back once i've got some more data.

[grumpywurzel]

Sounds like your clutch packs "may" be wearing, When the gearbox oil is cold it has a higher viscosity. On the other hand has your car been near a gearbox specialist or dealers to make sure that the box has the latest software as apparently a while back BMW released a patch to sort out the lurch. Unfortunately mine didn't have it done (and tbh I didn't know about it) before it lunched the box to bits

[Horizon]

http://www.bmwlogicseven.com/?p=3738
This is an interesting article

[Entwicklung34]

Hey fella's. Thanks for the input, i'm about to get investigations underway tomorrow as it's really irritating to drive.

It's interesting that it drives/shifts perfectly at all temps in 'manual' mode... This suggests to me that the box should, 'mechanically' be ok, no?

I'm going to first do a fluid level check tomorrow morning, then keep inpa connected and check codes etc and go for a drive to get the fluid hot and go from there. If the viscosity gets 'thinner' as it gets hotter, perhaps I underfilled it (I did follow the 40deg procedure etc, but the fluid temp rose fairly quickly and got to 49deg by the time I could ensure there was a steady stream).

Also, thanks for the article - reading it me feel like the g/box temp might be worth monitoring as perhaps it's not getting cooled adequately... i'll check this out tomorrow too.

Cross your fingers for me!

[Entwicklung34]

I'm back.

Checked fluid temp/level this morning and I opened the filler plug at 30 degrees and fluid gushed out (I wasn't expecting it) and so I refilled so it was flowing out slowly at 40 degrees and sealed her back up. I feel like it may have been a bit over-filled if it's even possible.

INPA showed no codes at all for the transmission, and that the transmission temp topped out at 90 degrees after/during a long test drive. (Engine temp stayed at 88degrees). I suppose this means temperature-wise it's ok, and therefore fluid level must be within reason.
The shifting seemed better than yesterday after the slight fluid adjustment today but still doing a bad 2-1 shift and sometimes 1-2 upshift (not really bad, but noticeable).

During shifting (2-1) and (1-2) the inpa screen was saying error at times (not leaving any codes though)... i'll try to show a picture:


Any ideas?

I'm thinking about asking my local specialist to do a software update to see if that works.