Speaking of X3 drivetrain issues....

[gavsadler]

I had a random thought, and I need to entertain the idea, so please aware me if this would be possible (even if it is ridiculous)

Is it possible to "disconnect" the front wheels from overall drivetrain operation? i.e could you configure an X3 (or other x-drive model) to be RWD only?

I've seen them fiddle with Audi models where they simply unplug the Haldex control unit which then makes the Quattro models FWD.

Thoughts / Comments?

And who is willing to experiment? Haha

 

[Philip Foglar]

I had a random thought, and I need to entertain the idea, so please aware me if this would be possible (even if it is ridiculous)

Is it possible to "disconnect" the front wheels from overall drivetrain operation? i.e could you configure an X3 (or other x-drive model) to be RWD only?

I've seen them fiddle with Audi models where they simply unplug the Haldex control unit which then makes the Quattro models FWD.

Thoughts / Comments?

And who is willing to experiment? Haha

I gather there is - my father in law has been doing some reading up and apparently there is something underneath that can be disconnected that disables the transfer case and you have a proper RWD again!

 

[B///Moodley]

But Xdrive only works when taking off and when you start losing traction from my understanding. The car is RWD when you're driving. Xdrive is electronically controlled and therefore can send 100% of the power to any of the four wheels in any percentage it wants but I'm sure if you disconnect the front drive shafts you will have a RWD car. They have done that to an R35 somewhere overseas when they were running it on a drag strip and the front drive shafts broke.


///M Power for the win...

 

[Philip Foglar]

As far as I understand it usually provides a 30/70 front/rear torque split, and changes this depending on traction requirement, so the transfer case is always working and making adjustments. And the problem is that if your tyres are not 100% the same diameter it upsets the system badly!

 

[gavsadler]

Exactly, which I think is really a poor design oversight if the fact that a few mm difference in rolling diameters of tyres can literally bring things to a grinding halt.

I can't really say that I'm aware of issues like this with other brands using AWD.

 

[Philip Foglar]

Earlier this evening we fitted the X3's now refurbished wheels with new Dunlop Sport SP 01 BMW Approved tyres, and the noise and transfer case issues are gone! So eating some humble pie with regards to the whole "BMW Approved tyre" theory, but it IS 100% the case when it comes especially to the narrow and wide setup. Before (and even after the transfer case was repaired) it would make a rumbling sound and vibration at around 40km/h over bumpy sections of road or just after going over a speed bump, and the most odd thing, if you had the cruise control set to say 100km/h and then turned it off to allow the car to slow to around 80km/h, then put the cruise control back on, as it starts to accelerate and hunt for a lower gear, there was this very strange sucking sound from the engine bay. Both issues no more!

 

[DieselFan]

Earlier this evening we fitted the X3's now refurbished wheels with new Dunlop Sport SP 01 BMW Approved tyres, and the noise and transfer case issues are gone! So eating some humble pie with regards to the whole "BMW Approved tyre" theory, but it IS 100% the case when it comes especially to the narrow and wide setup. Before (and even after the transfer case was repaired) it would make a rumbling sound and vibration at around 40km/h over bumpy sections of road or just after going over a speed bump, and the most odd thing, if you had the cruise control set to say 100km/h and then turned it off to allow the car to slow to around 80km/h, then put the cruise control back on, as it starts to accelerate and hunt for a lower gear, there was this very strange sucking sound from the engine bay. Both issues no more!

Did you previously have mismatched tyres front and back? Glad your issues is sorted.

 

[Philip Foglar]

Earlier this evening we fitted the X3's now refurbished wheels with new Dunlop Sport SP 01 BMW Approved tyres, and the noise and transfer case issues are gone! So eating some humble pie with regards to the whole "BMW Approved tyre" theory, but it IS 100% the case when it comes especially to the narrow and wide setup. Before (and even after the transfer case was repaired) it would make a rumbling sound and vibration at around 40km/h over bumpy sections of road or just after going over a speed bump, and the most odd thing, if you had the cruise control set to say 100km/h and then turned it off to allow the car to slow to around 80km/h, then put the cruise control back on, as it starts to accelerate and hunt for a lower gear, there was this very strange sucking sound from the engine bay. Both issues no more!

Did you previously have mismatched tyres front and back? Glad your issues is sorted.

Yes, when my father in law bought this X3 a few months back it had some horrid Pace and Federal tyres on which were noisy and just rubbish. So he got rid of them and initially bought a set of fairly new used Vredestein tyres that actually came off an X3 due to motorplan issues. Overall, not bad tyres, but they were roughly a 1 cm different in diameter front to rear. So while the rough tyre noise was gone, the transfer case was still not happy. But we didn't know that, and had Garage808 service the vehicle since it was due, and asked Colin to see what was going on. The transfer case according to him was in dire need of attention and was sent off to ZF. But he did also mention the tyre issue, so he called it 100% from the start.