Transfer Case Question

[yasavguy]

It looks like a few forum members had their Xfer case replaced under warranty.

1) What is the cause of the transfer case failure?

2) Is ignoring fluid leak the SOLE reason for the xfer case failure?

3) If you're out of warranty, where do you find a transfer case? I searched everywhere, don't see a used xfer case for F85

4) Can transfer case be rebuild?

Thanks!

[F85MTuNED]

Yes a transfer case can be rebuilt and also one of the main reasons why you don't see transfer cases for the X5M/X6M is because they rearly go bad.

Also T case will go bad due to neglect and abuse.

[yasavguy]

Originally Posted by F85MTuNED

Yes a transfer case can be rebuilt and also one of the main reasons why you don't see transfer cases for the X5M/X6M is because they rearly go bad.

Also T case will go bad due to neglect and abuse.

Good to know! I was getting the impression that it's a common failure point on this platform.

[F85MTuNED]

Originally Posted by yasavguy

Good to know! I was getting the impression that it's a common failure point on this platform.

No sir lol

[DgjoX6M2016]

I agree it seems uncommon as I do t see it here on board much. Mine failed from low fluid from a leak missed by CPO process. It felt like power was 'skipping' or there was a misfire under load.

Same with transmission and differential. They seem pretty durable. Might be worth poking around the previous gen board to see if issues there. Not sure same components....would have to verify.

[turboawd]

It's cheap and easy to replace fluids. It's a shame to burn up a transfer case due to low fluid.

[DgjoX6M2016]

Originally Posted by turboawd

It's cheap and easy to replace fluids. It's a shame to burn up a transfer case due to low fluid.

For sure. Watch for leaks. Mine happened on previous owner watch. At least this is what BMW said was the problem.

[Sophisticated Redneck]

The ATC 45L transfer case in the F86/F87 is nearly identical to the ATC450 used in the previous gen and holds very little fluid, just over half a quart (.6 Liter to be exact) so there is no buffer if you have a leak.

Also, the electromagnetic servo motor that drives the clutch plates is extremely sensitive to wear and fluid quality and needs periodic recalibration.

For the DIY'ers (and those out of warranty), before spending $$$$ on a replacement transfer case, try a simple fluid change at re-calibrate in ISTA.

This can solve many transfer case issues, especially once the mileage approaches 80K.

I was getting constant codes with mine and truck was basically undriveable (felt like a severe engine miss) unless I disconnected the transfer case fuse and put it in rwd only, which was kinda fun for awhile but drives/handles nowhere near as good as AWD. I was told the transfer case would need to be rebuilt or replaced.

A simple fluid change and recalibration in ISTA solved it. The recalibration is key.

So for the DIY's out there or those out of warranty, try doing the above before spending thousands.

[DgjoX6M2016]

Originally Posted by Sophisticated Redneck

The ATC 45L transfer case in the F86/F87 is nearly identical to the ATC450 used in the previous gen and holds very little fluid, just over half a quart (.6 Liter to be exact) so there is no buffer if you have a leak.

Also, the electromagnetic servo motor that drives the clutch plates is extremely sensitive to wear and fluid quality and needs periodic recalibration.

For the DIY'ers (and those out of warranty), before spending $$$$ on a replacement transfer case, try a simple fluid change at re-calibrate in ISTA.

This can solve many transfer case issues, especially once the mileage approaches 80K.

I was getting constant codes with mine and truck was basically undriveable (felt like a severe engine miss) unless I disconnected the transfer case fuse and put it in rwd only, which was kinda fun for awhile but drives/handles nowhere near as good as AWD. I was told the transfer case would need to be rebuilt or replaced.

A simple fluid change and recalibration in ISTA solved it. The recalibration is key.

So for the DIY's out there or those out of warranty, try doing the above before spending thousands.

The engine misfire feeling was the exact same thing I felt. I describe it like:

-misfire
-slight hesitations under power load
-not smooth power delivery under load

And there were NO codes or dash lights for me.

[Sophisticated Redneck]

Originally Posted by DgjoX6M2016

The engine misfire feeling was the exact same thing I felt. I describe it like:

-misfire
-slight hesitations under power load
-not smooth power delivery under load

And there were NO codes or dash lights for me.

Originally Posted by DgjoX6M2016

The engine misfire feeling was the exact same thing I felt. I describe it like:

-misfire
-slight hesitations under power load
-not smooth power delivery under load

And there were NO codes or dash lights for me.

Yep that's exactly how mine was also and no dash lights or standard OB2 codes, it's a BMW specific code (BMW code: CF80) that you can only read with ISTA software or a scanner like the foxwell NT510 loaded with BMW codes.

Pulling the fuse for the transfer case will disable it, light up you dash with DSC and 4x4 errors, force it in RWD mode only, and drive as such however all power delivery/engine missing sensations instantly disappeared. Good way to test if it's your transfer case or something else and kinda fun for a bit to feel how the truck drives in RWD mode only.

[Bocachairs]

Originally Posted by Sophisticated Redneck

The ATC 45L transfer case in the F86/F87 is nearly identical to the ATC450 used in the previous gen and holds very little fluid, just over half a quart (.6 Liter to be exact) so there is no buffer if you have a leak.

Also, the electromagnetic servo motor that drives the clutch plates is extremely sensitive to wear and fluid quality and needs periodic recalibration.

For the DIY'ers (and those out of warranty), before spending $$$$ on a replacement transfer case, try a simple fluid change at re-calibrate in ISTA.

This can solve many transfer case issues, especially once the mileage approaches 80K.

I was getting constant codes with mine and truck was basically undriveable (felt like a severe engine miss) unless I disconnected the transfer case fuse and put it in rwd only, which was kinda fun for awhile but drives/handles nowhere near as good as AWD. I was told the transfer case would need to be rebuilt or replaced.

A simple fluid change and recalibration in ISTA solved it. The recalibration is key.

So for the DIY's out there or those out of warranty, try doing the above before spending thousands.

I experienced stutter or shuttering thru most gears and had no concerns present while turning tight in a tight radius. Performed the above mentioned procedure. Changed fluid, recalibrated transfer case. At this time my concern has been eliminated!! Hopefully it's not a short term fix. I drove it like I stole it last night and still good!!

[Yuille36]

Originally Posted by Bocachairs

I experienced stutter or shuttering thru most gears and had no concerns present while turning tight in a tight radius. Performed the above mentioned procedure. Changed fluid, recalibrated transfer case. At this time my concern has been eliminated!! Hopefully it's not a short term fix. I drove it like I stole it last night and still good!!

Changing your transfer case fluid is easy, but you have to remove your transfer case cross member to get access to the fill/drain plug. Also get the fluid the BMW recommends. I just changed all my fluids last month; engine coolant, power steering, brake, differentials, transfer case and transmission fluids.

[dn325ci]

Originally Posted by Sophisticated Redneck

Yep that's exactly how mine was also and no dash lights or standard OB2 codes, it's a BMW specific code (BMW code: CF80) that you can only read with ISTA software or a scanner like the foxwell NT510 loaded with BMW codes.

Pulling the fuse for the transfer case will disable it, light up you dash with DSC and 4x4 errors, force it in RWD mode only, and drive as such however all power delivery/engine missing sensations instantly disappeared. Good way to test if it's your transfer case or something else and kinda fun for a bit to feel how the truck drives in RWD mode only.

My transfer case just started doing this. I'm preparing to change the fluid, but how is the recalibration done within ISTA? I've never used ISTA, but I'd rather give this a shot than pay the $7K I was just quoted for replacement.

[Klienfeld303]

Originally Posted by dn325ci

My transfer case just started doing this. I'm preparing to change the fluid, but how is the recalibration done within ISTA? I've never used ISTA, but I'd rather give this a shot than pay the $7K I was just quoted for replacement.

Doing my transmission and differential fluids next Monday 9am. This post got a brother SHOOK! 🥺

[Sophisticated Redneck]

Originally Posted by dn325ci

My transfer case just started doing this. I'm preparing to change the fluid, but how is the recalibration done within ISTA? I've never used ISTA, but I'd rather give this a shot than pay the $7K I was just quoted for replacement.

Its been so long I don't remember the steps but I do remember it not being easy to find as ISTA is not intuitive in the slightest, especially for first time users. I'll spin it back up today to refresh my memory and post back in this thread the steps.

[Sophisticated Redneck]

BTW, you can change transfer case oil without removing the cross member. Makes it much simpler and less then 10min to do this way. Grab a 14mm Allen wrench or 14mm hex socket, Dremel off 17mm in length, then grab long reach 14mm flex head wrench and compact fill pipe. I'll post links to Amazon for everything I used a bit later when I have a chance to dig them up.

[dn325ci]

Originally Posted by Sophisticated Redneck

Its been so long I don't remember the steps but I do remember it not being easy to find as ISTA is not intuitive in the slightest, especially for first time users. I'll spin it back up today to refresh my memory and post back in this thread the steps.

Thank you. I've got to get an ISTA laptop going now. I've had the cable since 2015 with the intention of coding, but never used it.

[dn325ci]

Originally Posted by Sophisticated Redneck

BTW, you can change transfer case oil without removing the cross member. Makes it much simpler and less then 10min to do this way. Grab a 14mm Allen wrench or 14mm hex socket, Dremel off about 1inch in length, then grab long reach 14mm flex head wrench and compact fill pipe. I'll post links to Amazon for everything I used a bit later when I have a chance to dig them up.

I've got a set of Carbyne shorties I can use for the 14mm. I need to get a rigid tube made up. Thank you!

[Sophisticated Redneck]

Originally Posted by dn325ci

I've got a set of Carbyne shorties I can use for the 14mm. I need to get a rigid tube made up. Thank you!

Good news on the laptop and cable, its going to be super close with the Carbyne, you may have to shave a few MM off the back of it. Total length of the tool I made was 17mm and if memory serves, it just cleared the frame when the fill plug was all the way loosened.

Posting instructions next

[Sophisticated Redneck]

Transfer Case Calibration:

Hook up battery charger (at least 10amp model)

Turn on ignition all the way (do not start engine) and hok up E-Net cable/laptop. Once connected with ISTA select:

Operations>>>Read Out Vehicle Data>>>Complete Identification.

After tests are complete, clear any faults with the transfer Case.

Next Select:

Vehicle Management>>>Service Functions>>>Power Train

Now Select:

Transfer Box Transmission Control Unit>>>Transfer Box (VTG) Calibration

A prompt comes up asking you if you have cleared all faults, engine off, etc.

Select Yes to perform calibration.

You will hear the servo motor in the transfer case engage for a few seconds. After this a screen will show the calibration results. Expect a correction in the area of 0.1-1.5 degrees.

Close out ISTA and switch off ignition. Start engine and take for a test drive. Many will find this will fix the "engine miss/trailer tugging" sensation. I nearly replaced the transfer case in mine 40K miles ago as I was told it was bad. Now at 170K miles with original transfer case in an E70 that is tuned to 600hp and is flogged daily. F85's transfer case should easily reach this mileage with proper care (change oil and re-calibrate every 50K miles ).

[Sophisticated Redneck]

Here are the tools needed to change the transfer case oil without removing the cross member:

14mm Allen wrench (cut off 17mm and use in wrench below) https://www.amazon.com/Bondhus-12284.../dp/B002YNQP5A

14mm ratcheting flex head wrench: https://www.amazon.com/gp/product/B01F512F7Y

Compact oil filler tube (use with your choice of hand pump, if you dont have a pump, search amazon, many pumps that already come with these fittings): https://www.amazon.com/Transmission-.../dp/B07G4D1DBZ

[Yuille36]

Yeah, I removed my cross member when I changed my transfer case fluid. On that day though, we changed both front and rear diff fluid, tranny and transfer case.