[mjleamy]

So Atlanta is getting a few inches of snow today and I decided to do some spirited driving entering a parking lot. As I made a turn into the lot, I gassed it and to my surprise my 330xi's ass-end fishtailed like a RWD. This is my first snow experience with the car. I don't recall my old A6 Quattro behaving anything like that. Granted Quattro is a much better snow technology than xDrive, but I am still surprised. Is this what others experience with their xi's?

Thanks! Mike

[rosica]

That's normal, Audi's are FWD biased and BMW's RWD biased. An Audi will overpower the front first, a BMW the rear first.

[zipstic]

Seems odd to me. Were you playing with DTC or DSC modes? Quattro Torsten systems have 50-50 splits whereas xi/xdrive is 40-60 so there isn't that much difference. Coming from my old A4 Quattro the BMW fishtails ever so slightly in the situation you were describing, but then DSC kicks in and points you in the right direction.

[shadow191]

RWD based AWD will fishtail. My FX is AWD, but based on RWD platform and I fishtailed a little bit in the same snow today. It's pretty advanced AWD too based on the Attessa system from the Skylines. Glad I wasn't in the E92, I saw a lot of RWD cars having trouble with hills. It was also getting icy, so even with AWD, at some point the tires just lose grip.

[mjleamy]

I would have thought with all of the 'sensing' going on that the AWD and traction control would save me from myself, but I guess not. But at least I wasn't one of the RWDs having trouble getting up hills.

[ArthurL]

I was going to drive the my 335i today for work but didn't want to risk it so I ended up driving the TL. What type of tires do you have? Think winters would've had more grip?

If I drove my 335 more, I probably would've bought winters for the car.

[pizza_party]

Standard torque split is 40% F 60% R, but can give 100% to either axle. As someone else mentioned, tires likely played a factor as well.

[ajsalida]

Originally Posted by mjleamy

So Atlanta is getting a few inches of snow today and I decided to do some spirited driving entering a parking lot. As I made a turn into the lot, I gassed it and to my surprise my 330xi's ass-end fishtailed like a RWD. This is my first snow experience with the car. I don't recall my old A6 Quattro behaving anything like that. Granted Quattro is a much better snow technology than xDrive, but I am still surprised. Is this what others experience with their xi's?

Thanks! Mike

What kind of tires do you have and how worn are they?

Rest of you guys down south, this is a great opportunity to play around with your cars in empty parking lots, see how they behave in snow and ice. Play with DTC/DSC button.

BTW have read Xdrive at low speeds and sharp steering angles goes RWD only.

[mjleamy]

My tires have less than 1,000 miles on them. They are Hankook's of some type.

[ajsalida]

Originally Posted by mjleamy

My tires have less than 1,000 miles on them. They are Hankook's of some type.

Uuum, are they snow tires or all seasons or sticky summer tires?

[pizza_party]

Originally Posted by ajsalida

BTW have read Xdrive at low speeds and sharp steering angles goes RWD only.

This is true as well, so the drivetrain will not "bind"

Also I found interesting, that if xdrive is going to fail completely, it will go to 100% RWD

[ajsalida]

Originally Posted by pizza_party

Also I found interesting, that if xdrive is going to fail completely, it will go to 100% RWD

Yeah it has to, it basically has an ordinary unbroken rear drive shaft and the transfer case only engages or disengages front driveshaft. Rear is always engaged IOW, and front can get no more rotation than rear.

[mjleamy]

Originally Posted by ajsalida

Uuum, are they snow tires or all seasons or sticky summer tires?

Uuum, see my post - "of some type." This implies I don't have the information handy, and I probably will not go outside just to answer your question

[ajsalida]

Originally Posted by mjleamy

Uuum, see my post - "of some type." This implies I don't have the information handy, and I probably will not go outside just to answer your question

Aha, well one might infer then that your tires had something to do with what was going on. AWD does not repeal laws of physics.

[Jeff@TopGearSolutions]

Originally Posted by mjleamy

So Atlanta is getting a few inches of snow today and I decided to do some spirited driving entering a parking lot. As I made a turn into the lot, I gassed it and to my surprise my 330xi's ass-end fishtailed like a RWD. This is my first snow experience with the car. I don't recall my old A6 Quattro behaving anything like that. Granted Quattro is a much better snow technology than xDrive, but I am still surprised. Is this what others experience with their xi's?

Thanks! Mike

Perfectly normal as it's RWD bias.

[AWD Addict]

Originally Posted by mjleamy

I would have thought with all of the 'sensing' going on that the AWD and traction control would save me from myself, but I guess not. But at least I wasn't one of the RWDs having trouble getting up hills.

It still does interfere a lot, if you haven't put DTC on, or turned all traction control off. It'l go so far as to cut throttle on you, despite mashing the pedal (which pisses me off.)

If it's snowing out, I hit the DTC button right away, no matter what. With that setting, this car behaves like a normal AWD vehicle, and if you want, will allow you to send the ass out much more "normally"

With it all off, the car is hilariously fun, but basically a sled.

As noted above, your summer tires were probably the largest player in that condition.

[mastermayhm]

its more of a 40-60 ratio... the rear gets more power

[AWD Addict]

Originally Posted by mastermayhm

its more of a 40-60 ratio... the rear gets more power

It depends on speed and traction. At highway speed, much of the power is rear (80% iirc), as it is at start/launch.

[ajsalida]

Originally Posted by pizza_party

Standard torque split is 40% F 60% R, but can give 100% to either axle. As someone else mentioned, tires likely played a factor as well.

Missed this comment earlier. System cannot go 100% front, at most 50%. As noted earlier rear axle cannot be disengaged. I know what BMW marketing says they are being dishonest.

[mastermayhm]

Originally Posted by AWD Addict

It depends on speed and traction. At highway speed, much of the power is rear (80% iirc), as it is at start/launch.

ahh too true.. you are correct sir

[ajsalida]

I have read but cannot confirm that front disengages completely above a certain HWY speed.

[mjleamy]

Thanks for all of the great discussion. I am going to go with it is normal for a heavy foot, large steering input, and slow speed to result in an ass-end that fishtails on an xi. Yes, tires will play a role in how dramatic that fishtail is, but there is enough torque in these cars to make any tire compound/tread-pattern/etc. break loose. I guess one thing I failed to mention is that my 330xi has a manual transmission. That probably has little to do with what happened, but it does eliminate the possibility for any slip in a torque converter.