11-14-2017, 06:13 PM | #1 |
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Xdrive power distribution
While driving my loaner car today (while my M240Xi awaits its repairs), I was wondering about power distribution for the Xdrive. The 330i loaner I'm driving is RWD, and while under powered in comparison to my M240Xi with Dinan stage 1, it felt strangely similar when driving in a "spirited" manner. I used to have an Audi S4, and it was near impossible to get the tail to step out under power and seemed pretty well balanced front/rear. The M240Xi, though AWD, seems much more rear wheel biased when driving with some pep, and feels much more akin to a RWD car than the Audi ever did.
So, here's my question. Just how does the BMW Xdrive system work? How is power distributed? 60/40, 70/30, or is it pretty much a RWD car until the front wheels need power? |
11-14-2017, 07:08 PM | #4 |
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I find the xDrive on my M240i to be Very Different from the open diff RWD of my 135is. It was quite easy to get the 135is to try to step out the rear, and easy to get it to cut power since it didn't have an LSD. In the same corners with roughly the same level of aggresXXXXX assertiveness, the xDrive is clearly pulling more from the front wheels, and is both less inclined either to understeer (which the 135 was capable of) or to oversteer.
The M240i xDrive is far more stable in cornering. I suppose that would be less fun if you really want to hoon around, but I'm more about fast, smooth, and stable than sliding. |
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11-15-2017, 09:08 AM | #5 | |
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11-15-2017, 12:19 PM | #6 |
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Very cool video - I'd thought that all the Audi's had the Haldex. Also cool to know the xdrive can put 100% to just one axle. I've been loving the 4wd handling profile more and more as I get used to it - thought I'd miss RWD, but I think this is better.
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11-15-2017, 09:25 PM | #7 | ||
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Haven't had a chance to drive an Xdrive in the snow to compare to the S4 I used to own. The S4 always felt stable and confident in slippery/snowy conditions. I bought my M240 back in early February, but D.C. area really didn't get much more than a dusting after that, so I never got a chance to compare it yet. |
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11-16-2017, 08:58 AM | #8 | |
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Then with the 2er going xDrive in 2015, we went down to 1 vehicle. During the past 2 winters in the M235xi, I have felt every bit as confident in the snow and foul weather as I ever did with any of the SUVs we owned in the past. BTW, I only have the OEM RFT all-seasons on the M235xi and they work well enough for me in the winter (P.S. don't tell anyone else here about this last part or I'll get the "winter tire" speech).
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11-16-2017, 09:27 AM | #9 | |
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11-16-2017, 10:49 AM | #10 |
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Much of it has to do with the fact that the Audi has a lot more weight hanging out in front the front axle. It makes the car far more prone to understeer and less willing to rotate, especially considering that more Audis do not have a RWD biased AWD system.
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11-16-2017, 11:18 AM | #11 |
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It basically comes down to the fact that a tire can only do one thing at a time. It can accelerate, decelerate, or turn.
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11-16-2017, 11:52 AM | #12 | |
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11-16-2017, 12:26 PM | #13 | |
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'22 M440xi GC (BSM/Tacora) Previous: 2017 M240i Convertible; 2016 X5 50i; 2017 Boxster 718s; 2012 328iT Sport; 2009 X5 3.0; 2006 M3C; 2006 530xiT; 2003 325xiT; 2002 330i Sport; 2001 Z3 2.5; 2001 330i.
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11-16-2017, 06:07 PM | #14 | |
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The A3/S3/RS3 and TT variants (MQB platform with transverse-mounted engines) use a Haldex-based system. It's under debate what the capabilities of the quattro with Ultra are. Audi has made claims it can direct 100% to the rear or front, but with their design, it seems difficult to believe that is the case. Those who have driven in one universally say they cannot distinguish between that system and the previous Torsen-based quattro, though, which is mechanically able to distribute torque up to 75% to the front wheels and 85% to the rear wheels. |
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12-04-2017, 06:54 PM | #15 | ||
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