Quote:
Originally Posted by kaptain
Here is my understanding of the pre-xdrive 4wd system.
Pre xDrive X's have a relatively primitive 4wd System, I think its almost the same as my old explorer. There are also early (2000 or 2001) X5's that do not have 4wd at all. Was the wheel spinning in the rear? or front?
If you have the pre-x drive 4 wheel then I think you should see two wheels, 1 front and 1 back move. The pre-xdrive X5's lack any kind of locking/limited slip differentials between left and right (open diff). There is a DSC gizmo that uses the brakes to act like a limited slip diff but who knows how well it really works.
So what I think this means is that if there is a slab of ice under one front tire, and one rear tire, and your car is at a standstill, you will most likely not find traction. The DSC locking diff might get you moving just enough to get momentum.
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I'd agree with Fraser's description. It is an open diff front/rear, with a fixed torque split (38/62 front/rear). As a result, with one wheel on ice you will spin, disregarding the effect of the wheel-brake traction control system (DSC/DTC). DSC works well in my experience, as long as you don't spin the wheels long enough to overheat the brakes. Alternatively, you can turn DSC off, and purposely spin the wheels to try and churn out of a snowbank, for example.
I don't think the BMW awd system is particularly primitive; your Explorer, in locked mode, is by comparison primitive for on-road use, but effective for off-road use.
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2007 X3 3.0si, 6 MT, Premium, White
Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue
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