Xdrive questions
 

When did BMW make change in the AWD/Xdrive system?

I think things changed in 2004...?

What was the change?

The change was made along with the introdution of the facelifted model, late 2003, early 2004. The XDrive is a more advanced 4x4 system giving the X5 more ability on the slippy stuff, but without the low ratio gear box, it will never be a match for the likes of a Land Rover on the rough stuff.

Don

Here's the XDrive description from Wikipedia which sums it up nicely:

"BMW invented a new four-wheel drive system dubbed xDrive shared both in the X5 and X3 in 2004. Instead of using the previous X5 system which consisted of power being split 60-40 (rear wheels-front wheels) and DSC to brake wheels losing traction, xDrive could variably cut off power to the front or rear axles in a matter of milliseconds, while transferring 100% of the engine power to either, thus allowing the vehicle to regain traction quickly."

Well said, I just went along with the lay mans explanation. Either way, the car preforms much better in the snow as I found out last winter.

Don

And I'm just a copying and pasting kind of guy. No big deal. Together we create knowledge! :thumbup:

I think the differences between the old and the new 4wd system on the X5 are best summed up in this article I found on the net:

"BMW's revised 4wd system since 2004 is xDrive, an 'intelligent' state-of-the-art four-wheel drive system first seen on the X3. XDrive ensures that drive forces are always delivered to the axle that needs it most. In an instant. It's comprised of two key ingredients that regulate power to each wheel — a centrally mounted, electronically-activated multi-plate clutch to distribute power between axles, combined with BMW's Dynamic Stability Control system to regulate power to individual wheels. Responding instantly, xDrive is far quicker than more conventional four-wheel drive systems that require the build up of hydraulic pressure before they can change drive distribution.

The 'intelligence' of xDrive comes from DSC, which delivers a wealth of vehicle data including individual wheel speed, steering angle, lateral acceleration and yaw rates. By constantly processing this information, xDrive can predict traction loss and transfer drive where it is most needed to maintain grip.

Naturally DSC can intervene but — because of xDrive's ability to re-direct power to prevent traction loss — it does so far less frequently and only then in extreme circumstances. Where traction loss is un-avoidable, DSC cuts power and, if necessary, applies brakes to individual wheels allowing the car to regain a foothold, but it does not necessarily slow the car's progress.

As a driver you don't need to appreciate DSC's inner workings. You only need to know that it's there 24/7 like a guardian angel, safeguarding your every move however bad the weather conditions. In layman's terms, the practical benefits of this intelligent 4WD set-up are twofold. On the road, traction and agility are improved whilst over- and under-steer are countered during cornering. Off the road, traction is significantly improved as xDrive channels drive forces to the axle with most grip rather than cutting engine power or braking troubled wheels. "

Wow, I totally wrote that... hahaha ! Amazing...

In fact I wrote both the X5 & X3 articles on Wikipedia !

and here is a whole magazine article on Xdrive
http://www.janixworld.com/x5/misc/X5%20xdrive.pdf

- Jan