X-Drive Module Modifications?
 

Hi, Everyone.

I was wondering if anyone knew whether there were any chips or software that could set the X-Drive settings to a certain specification and remain there indefinitely. I know that a few companies offer such solutions for the VW/Audi/Porsche/Lamborghini cars (basically, all VW Quattro) but I haven't come up with anything for the X-Drive. What would happen if I simply deleted the X-Drive module; would the car go 50/50 or 100% rear or into limp mode and therefore stop working altogether?

Thanks!

Haven't heard of anything for the X....but honestly haven't really looked either.

Out of curiosity, why are you looking for such a gizmo?

Modifying the X-Drive would be quite a challenge; it varies torque proportion to the front wheels continuously under dynamic conditions using inputs from speed sensors, yaw, steering angle, DSC, etc. Power to the servo motor in the transfer case is routed through the 70006 module itself. The programming and interpretation of the driving dynamics are complex, BUT the mechanism for the resulting proportional torque control at the transfer case itself is super simple. All you have there is a servo motor applying torque to a clutch pack through a lever.

If you wanted to control the torque proportion manually (100% rear, 50/50, whatever), you could easily do so by providing your own servo signal at the transfer case. Pin 1 is the servo control signal, Pin 8 is the ground ckt for the servo motor. Get the signal correct (it's not going to be anything special; servo motor control is nothing new or special, even in a BMW), and you can do whatever you want.

However, because of the intimate integration of the XDrive with the DSC, anti-lock braking, and related functions, I strongly suspect (actually, I am fairly certain) that any intervention will also disable those modules (thus the dash lights up like a Christmas tree, and those functions are all compromised). That's probably why you won't likely find any commercially produced software level over-rides to the programming. Nobody will want to be associated with changes that may compromise the stability system; even if you didn't sue them in the event of an accident, nothing says a third party wouldn't.

Not saying you shouldn't check it out and learn about the system if you want to, etc., but I doubt you'll find anyone providing a product to influence this area of the car.

You could probably code out the transfer case. You would need to reconfigure the driveline with something similar. So if you code out the transfer case, you would need to make the car think it has something else, like a 5 series driveline. I have never tried this stuff, but I figure that is how it would work with coding the car. I know you can code out the air suspension.

Thanks for the responses, guys. I figured that messing with it would screw with the TC, ABS, etc.

I was asking mostly out of curiosity - I'm not really planning on modifying anything. The reason I was asking was because I also have a pre-facelift X5 and prefer the mechanical/permanent transfer case rather than a clutch-actuated unit.

Anyhow, thanks anyways :)

It would be nice to have a button to force a full lock. Done properly it should disengage when speed exceeds certain limit. That would be very useful when trying get moving from stand still on slippery surface.

This is one of the items I'd like to see there already from the factory and I wonder why BMW hasn't put any these kind of features there already. It's just a button and few extra lines in the software.

Our X5s do have this - this is exactly what "Hill Descent Control" does. HDC also turns off automatically at something like 30mph. I doubt HDC works on the yaw sensor or anything so I'm betting it's going to fully lock whether your descending or ascending or driving in a straight line. Curious - I should try it. I know it works on descent (I've used it before) but I've never used it on an incline or in a straight line. Hrmmm...

X drive doesn't have a full lock, that isn't part of the design. What the clutches do is vary torque balance from front to rear, they don't lock together the front and rear output shafts, those remain open.

HDC doesn't do anything with the transfer case. It is a brake control, applied individually to each wheel based on feedback from the ABS sensors. It is just a different routine in the ABS system, with added throttle control.

:iagree:
It seems like I read somewhere that the X-Drive goes into rear-drive mode above 120 mph? So there must be some type of setting/logic with everything intact and rear wheel drive only.

It would be nice if you had the option to run in rear wheel only mode with DSC and ABS functional still. Maybe a fair weather/summer mode for a different driving dynamic. That being said, pushing the envelope in an X5/X3 could get you into some trouble. There's a lot of mass up high in these machines, and even though its a pretty stable platform, my guess is it relies more on the x-drive dynamics more than you know in a performance/saftey function.

Honestly, if your driving within reason, and not sling shooting a 60 mph power drift on an on ramp, probably not that critical. However,the AWD with DSC is like wearing a safety belt. You put it on because you never know when your going to truly need it. A highway speed maneuver on the interstate avoiding a collision with an object/person/animal/another car, might have two distinct outcomes based upon the driving dynamics you choose, if you had the choice. Just thinking out loud. Maybe mute the system and let it do an override if a set of conditions is sensed, kinda like hitting the DSC button. Its working in the background, ready to intervene when called upon. Just an idea.

The other side to this option would possibly allow for slight enhanced economy at the ol' gas pump.

Bentley manual had a very good description on how the X drive system works. I am quite positive it becomes RWD only much closer to 80mph. It also becomes RWD, under full throttle with no front wheel slip. It can also send 100% of the power to the front or rear.