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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > All-Wheel-Drive (Xi / xDrive) Talk > Xi Technical Information



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      06-09-2008, 10:04 AM   #1
E nine T
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Xi Technical Information

Since it seems like everyone always posts redundant Xi questions in the General Forum, maybe we can compile info in one thread for a sticky.

I'll start:

"Sporty on any surface.
The xDrive all-wheel drive system.
All-wheel drive means traction, directional stability and driving safety. With BMW xDrive, it also means driving pleasure. On dry tarmac, xDrive transfers 40% of the torque to the front wheels and 60% to the rear, allowing the car to retain the sporty handling characteristics you'd expect from a BMW. If the situation or surface changes, xDrive redistributes torque within milliseconds to prevent over- or understeer at the onset. It's the perfect blend of safety, traction and agility."

"The BMW all-wheel drive system, xDrive, ensures your BMW has the best possible traction at all times, enhancing agility and keeping you safely on track, even on fast bends.

xDrive is the permanent all-wheel drive system from BMW: under normal circumstances, it distributes driver power between the front and rear axles in a 40:60 ratio, and changes this figure variably when the road surface or overall driving conditions change.
Acting virtually instantaneously and a manner so subtle as to be go virtually unnoticed by the vehicle’s occupants, xDrive can direct up to 100% of drive forces to one axle. Enabling the driver to start up effortlessly even on slippery surfaces or steep hills, xDrive routes all power to the axles with the greatest traction. When parking, the system reacts to the need for high manoeuvrability at low speed by opening the clutch completely so the powertrain functions optimally.
At the first sign of understeering, drive power to the front axle is reduced. If oversteering is detected, xDrive directs more power to the front axle. Thanks to this dynamic redistribution of power, vehicle stability returns to normal even before the driver notices anything amiss.
Driving on a winding road or taking a fast bend in dynamic style is particularly enjoyable with xDrive: you feel as if your BMW is being guided along the curve. xDrive ensures that none of drive power is wasted on a loss of traction: every kilowatt of power is effectively brought to bear on the road.
xDrive is regulated by Dynamic Stability Control (DSC) and uses information from the latter system’s sensors to monitor road conditions. In addition, brake force courtesy of DSC is used when there is traction difference between the two sides of the vehicle and wheel spin is likely. "





Can anyone confirm that X-drive will send 100% of power to the rear wheels when you go 100+ mph?
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      06-10-2008, 01:11 AM   #2
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Getting torque to the front wheels is accomplished with a multiplate clutch that works like a PTO off the driveshaft. If the clutch is fully engaged, all the torque will go to the front wheels, fully disengaged and all the power goes to the rear drive shaft. So if you completely fried your xDrive clutch, you'd end up with a heavier 335i.

If you push hard around an off ramp, you' can really feel the xDrive clutch clamping down hard to divert torque to the front wheels to keep the ass end from kicking out and then opening as you straighten out.

Regarding the 100 mph thing, I've read this in many places but nothing official. It makes sense though.
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      06-10-2008, 03:53 AM   #3
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03/07 E90 335xi  [1.00]
BMW xDrive Video.

http://www.metacafe.com/watch/827462/bmw_xdrive/





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      06-10-2008, 05:00 PM   #4
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Quote:
Originally Posted by E nine T View Post
every kilowatt of power is effectively brought to bear on the road.
How many kilowatts am I pumping in stock trim? 328 xiT...
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      06-10-2008, 05:07 PM   #5
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I am not sure about the 100+ mph thing but I have driven my car t the 155mph electronically controlled speed limit in the Autobahn and the car feels extremely stable and planted. Then a Ferrari flew past me like I was standing still. It was a great day.
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      06-15-2008, 10:30 PM   #6
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shock are ALOT stiffer, but handels so much nicer
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      07-09-2008, 12:46 PM   #7
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New to the E90, just bought 328xi; why do the xi sport packages not include suspension upgrades?
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      07-09-2008, 06:56 PM   #8
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Quote:
Originally Posted by l8apexer View Post
New to the E90, just bought 328xi; why do the xi sport packages not include suspension upgrades?
good question.. I believe it is because the Xis are already stiffer than the I's. Or BMW got lazy. Either way there should be an upgrade with the sport package, hence the name sport package. But there are suspension mods you can do.
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      07-10-2008, 08:44 PM   #9
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Quote:
Originally Posted by Mystic_blue View Post
Does the sport package mean that the limiter is changed to 150 mph......?

What other attributes does the sport provide??? besides the seats and the wheel.
xi sport package includes: Seats, Steering Wheel, Wheels upgrades. Higher speed limiter only comes if you order the summer tires and wheel option (due to lower speed rating for all season tires).
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