Diff fluid changes and transfer case

[diesaroo]

Originally Posted by JCL

Differentials are pretty straightforward. 60,000 miles is a pretty good interval.

As you have an x-drive model, the transfer case uses a special BMW fluid. When it is changed, there is a reset procedure for the transfer case control unit. A service computer is required to do that reset. 60,000 miles is a pretty good interval for this compartment as well.

Yes, there are lots of threads here about changing these fluids. A search will show them. Search on the full site, not just the E70 forum.

Gonna resurrect this thread...it being Easter...ok that was bad.

Anyways, I have looked in the TIS and do not see where the transfer case unit has to be reset when changing the oil, only when the transfer case is being replaced. Any references?

Thanks

[JCL]

Originally Posted by diesaroo

Gonna resurrect this thread...it being Easter...ok that was bad.

Anyways, I have looked in the TIS and do not see where the transfer case unit has to be reset when changing the oil, only when the transfer case is being replaced. Any references?

Thanks

If a fault code is reset from the fluid being out of spec (as determined by measuring slip and engagement pressure) then that has to be reset.

If the fluid is changed prior to that code being logged, then it is just the adaptations.

What has to be done additionally when the transfer case is being replaced is that the vehicle needs coding related to the classification resistor.

Here are some sources.

http://www.xoutpost.com/bmw-sav-foru...intenance.html


http://www.xoutpost.com/bmw-sav-foru...available.html


This next one is about the X3 (which uses a different version of the same transfer case, same technology)


http://www.xoutpost.com/bmw-sav-forums/x3-e83-forum/67524-ecs-tuning-xdrive-x3-oem-bmw-transfer-case-fluid-now-available.html

[diesaroo]

Originally Posted by JCL

If a fault code is reset from the fluid being out of spec (as determined by measuring slip and engagement pressure) then that has to be reset.

If the fluid is changed prior to that code being logged, then it is just the adaptations.

What has to be done additionally when the transfer case is being replaced is that the vehicle needs coding related to the classification resistor.

Here are some sources.

http://www.xoutpost.com/bmw-sav-foru...intenance.html


http://www.xoutpost.com/bmw-sav-foru...available.html


This next one is about the X3 (which uses a different version of the same transfer case, same technology)


http://www.xoutpost.com/bmw-sav-forums/x3-e83-forum/67524-ecs-tuning-xdrive-x3-oem-bmw-transfer-case-fluid-now-available.html

Thanks for the sources. But there is just one thing, assuming the VTG module must be reset to purge intself of adaptation values even if a code has not been generated to properly calibrate the operation of the TC, why is this information only shown on an X-Drive training manual? I saw nothing of the sort on the TIS and mine is a version <1year old. I was under the impression that all service data was in the TIS, or at least a direction was given in the TIS if something else was required as part of the service procedure. Killcrap? Weasel?

P.S. I understand that people employed by BMW might not want to post from the TIS, but can I get a reference # or directory? TIA

[JCL]

I don't have a copy of the TIS, so I can't provide original references. However, the following are all posted on this site. Credit given to texmin, ripp222, and skeetjunkie:

Posted in response to where to find the TIS reference:

Originally Posted by texmin

Look under:

Repair Instructions / 00 Maintenance and General Data / 0011572 Changing oil in the transfer box (ATC 400/500)

The first line in the document states "When changing the gear oil it is necessary to delete the self-adapting wear values in the transfer box control unit"

I've never cleared the adaptation values since I did the job and have had no problems at all.

texmin wrote up a DIY, found the reference in the TIS, and reported that he never did do it. Not sure if he has done so since.

Posted in reference to how to cleare the VTG fault:

Originally Posted by ripp222

My X5 VTG had the fault logged around 50,000 miles. Here is the relavent SIB:

=====================

SI B27 01 07
Intermediate and Special Transmission
April 2007

Technical Service

SUBJECT

Transfer case (VTG) Fault Code 54C6 Oil wear - Value too high
MODEL
E53 (X5) from 10/03 to 02/05 production
E83 (X3) to 02/05 production
SITUATION
After interrogating the fault memory, as part of an Inspection I or II maintenance service or another repair
requiring a diagnostics procedure, fault code 54C6 Oil wear – Value too high is stored. This fault will not
illuminate a warning lamp.
CAUSE
Transfer case fluid (non lifetime) wear value limit was exceeded.
CORRECTION
Replace the fluid in the transfer case.
PARTS INFORMATION
Part Number Description Quantity
83 22 0 397 244 TF0870 Fluid 1 = 1 liter

Note: Before opening, shake the container to evenly mix the additives in the fluid.

That refers specifically to the VTG fault when the fluid no longer meets spec, not the adaptation values that are to be reset whether or not the fault has been raised.

Posted in a discussion on why it matters:

Originally Posted by skeetjunkie

Additional info from Mike Miller on the resetting the control unit:

The X-Drive transfer case must be reset electronically at the dealership after the oil is changed. You can change the transfer case oil yourself or have it done wherever you want, but the vehicle does have to go back to the dealer to have the transfer case reset. This “resetting” procedure is only possible on the BMW service computer.

Specifically the “reset” uses the actuator inside the transfer case to gauge the thickness of the remaining clutch material. The transfer case then relearns the end stops of the clutch pack to compensate for wear. The electric motor inside the X-Drive transfer case then knows how much it has to apply the clutch pack in order to transfer power when
necessary.

It is that last information from Mike Miller that gives me pause to think. It makes sense that the adaptations are important for future transfer case clutch plate life, not just for a warning as to when the fluid is due to be replaced. Many have posted that they changed the fluid without resetting the adaptations, and it still drove fine. That is certainly possible, but IMO they won't be able to judge their success until they see if the transfer case lasts as long as expected without the adaptations being reset. Incorrect clutch pressures will lead to shortened clutch plate life if too low, and potentially to actuator motor failures if too high.

[diesaroo]

Originally Posted by JCL

I don't have a copy of the TIS, so I can't provide original references. However, the following are all posted on this site. Credit given to texmin, ripp222, and skeetjunkie:

Posted in response to where to find the TIS reference:



texmin wrote up a DIY, found the reference in the TIS, and reported that he never did do it. Not sure if he has done so since.

Posted in reference to how to cleare the VTG fault:



That refers specifically to the VTG fault when the fluid no longer meets spec, not the adaptation values that are to be reset whether or not the fault has been raised.

Posted in a discussion on why it matters:



It is that last information from Mike Miller that gives me pause to think. It makes sense that the adaptations are important for future transfer case clutch plate life, not just for a warning as to when the fluid is due to be replaced. Many have posted that they changed the fluid without resetting the adaptations, and it still drove fine. That is certainly possible, but IMO they won't be able to judge their success until they see if the transfer case lasts as long as expected without the adaptations being reset. Incorrect clutch pressures will lead to shortened clutch plate life if too low, and potentially to actuator motor failures if too high.

Jeff, I totally agree with your logic. My TC is a little newer than the ones you are referencing (ATC 700). I'm looking at 27 00 Repleneshing / Changing Transfer Case Oil (ATC 700). Nowhere in the document does it state that the BMW repair diagnostics should be consulted. It does say so in a different repair procedure regarding the TC replacement or the replacement of the TC servomotor that BMW Repair Diagnostics should be run.

I guess I'm still wondering if the newer TC software has been changed from the prevoius models or do I simply not have enough information?..

[diesaroo]

I just thought I would share a little info that I found recently in the newest 5-series Bentley Manual (E60). In the Transfer Case section, under clutch actuator (VTG) motor, it states:

“Because of mechanical tolerances in production, the characteristic curve of the multi-disc clutch locking torque varies slightly. At the factory, once the actual locking torque is measured on the clutch test bench, a resistor is attached to the clutch actuator. The resistor value (Classification) determines clutch locking torque characteristics.
1. Clutch actuator drive gear
2. Clutch actuator (servo motor)
3. Classification resistor
Each time the engine is started, the transfer case module measures the resistor value once and selects the optimum program map for transfer case engagement.”

Also, in the Transfer Case Fluid service section, the only mention of electronics is that the transfer case control module monitors oil life to determine when the oil is to be changed. There are no other caveats other than to use the correct BMW oil, filling to the bottom of the fill hole and torque the drain plug to spec. Although this TC is the ATC 300 rather than the 700 (X5), the procedure is consistent with my version of the TIS for the ATC 700.

So it seems there must have been a change in the software that required previous versions to have it reset with the dealer computer whereas now (>2009) it appears to reset itself upon startup.

[JCL]

If there is a change, it may be between the ATC 400 and ATC 500 vs the newer ATC 700 in the E70. We would likely need killcrap or weasel to advise specifically.