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Old 01-27-2010, 12:00 PM
vrooom3440 vrooom3440 is offline
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Location: Granite Bay, CA
Join Date: Sep 2009
Posts: 56
Mein Auto: 330i/X3/El Camino
Originally Posted by foxwalk View Post
vroom3440: did you watch the video? it isn't using the brakes to do that.

Thanks for posting that video, it was really awesome.
Yes I have watched the video and yes they can and very likely do use the brakes to do that. The last bit with the Quattro and Xdrive on the rollers is very telling. The Quattro does what I would expect of an open differential and just spins the rear wheels. The Xdrive gives the rear wheels a little bit of spin at which point the computer notes a mismatch between front and rear rotational speeds and applies the rear brakes to slow that rotation down to match the front. The affect is that the rear wheels become harder to turn, the front wheels easier relative to rears, and power gets transferred to front.
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