[LaserPower]

It can be that your handbrake is loose. I had that happen in my E90 330 xi manual. When parked on a steep incline, the car will roll back even I thought I had my handbrake fully engaged. I had to pull extra hard (like really hard...pulled pass the top click with both hands) on the handbrake to stop the car from rolling. I would suggest to have the dealer check the tension on the handbrake.

[adidoman]

Originally Posted by critical05

Might be silly to someone driving by, I would try to push the car down the driveway and see if you can move the car. Try pushing off of the b piller, see if you can move the car, it's strong enough. If so, find out if the wheels rotate or slide. Would be a start in figuring what's going on.

I may to try that when it snows next. I'm not going to put winter tires on yet till I figure out the cause, and if it's just the tires it's an easy fix

[adidoman]

Originally Posted by GB-335xiCoupe

Like others said, put wheel chocks down. Put a piece of electric tape on the bottom edge of one of the wheels so you can tell if it has rotated or not. Also I can't believe no one else has said it: When you park, turn your wheel one way or the other, so if it does move, it doesn't go into traffic/ravine, etc.

I like the electric tape idea to see if it's actually moving or not. And I keep the wheels the way they should on any slope, but I've only had this happen in the snow on a driveway (2 different driveways, and 2 different 335xi's)

[adidoman]

Originally Posted by LaserPower

It can be that your handbrake is loose. I had that happen in my E90 330 xi manual. When parked on a steep incline, the car will roll back even I thought I had my handbrake fully engaged. I had to pull extra hard (like really hard...pulled pass the top click with both hands) on the handbrake to stop the car from rolling. I would suggest to have the dealer check the tension on the handbrake.

The only thing I have against that is that it's happening to two different cars, both auto though, unless both handbrakes are not working

[GB-335xiCoupe]

What kind of an incline are we talking about here? Pics would help.
Autos simply should not do this sliding... unless you are parked on glaze ICE.

Also, you said you turn the wheel... if that is the case, then if the front wheels spin, your car will turn, and not slide straight down the hill, or at least end up sideways. If your front wheels do not spin, then the car will slide straight down. Are you parking with the car pointed up- or down- hill?

[adidoman]

Originally Posted by GB-335xiCoupe

What kind of an incline are we talking about here? Pics would help.
Autos simply should not do this sliding... unless you are parked on glaze ICE.

Also, you said you turn the wheel... if that is the case, then if the front wheels spin, your car will turn, and not slide straight down the hill, or at least end up sideways. If your front wheels do not spin, then the car will slide straight down. Are you parking with the car pointed up- or down- hill?

I'll upload some pictures tomorrow of both driveways

[rosica]

The front front driveshaft is never locked to the t.c. (a fundamental difference between awd and 4wd) so this problem is possible I would say you need snow tires do you have trouble getting up your driveway or as soon as you stop does the car slide back a bit. Go to 4:39 of this video to see an xdrive roll backwards on a slippery surface

[adidoman]

Originally Posted by rosica

The front front driveshaft is never locked to the t.c. (a fundamental difference between awd and 4wd) so this problem is possible I would say you need snow tires do you have trouble getting up your driveway or as soon as you stop does the car slide back a bit. Go to 4:39 of this video to see an xdrive roll backwards on a slippery sureface http://<div class="youtube-playerCon.../iframe></div>

It says that is a local file

[rosica]

Originally Posted by adidoman

It says that is a local file

[ajsalida]

I remember seeing that episode when it first came out and thought it sucked. Anyway I think you are right about what is happening, however in that vid even if the front were locked it still would have slid down wet grass on a steep hill, as would any 4x4 with center dif locked up and those tires.

So maybe the simplest explanation is the summer tires + steep hill + ice, and maybe something happening with temps overnight dropping low enough to freeze and start a slide. IOW has nothing to do with AWD or front axle not locking up.

rant: I really hate "journalists" who try to make whatever personal point about something by distorting facts and presenting "evidence" like the video above. Put some real off road tires on an X6 it would do fine up that particular hill, even though it was never meant to be a Land Rover or have that capability. Might as well complain an AWD 911 turbo does poorly off road with race slicks on. The AWD on the X6 is not meant for Jeep trails or Paris-Dakar.

[rosica]

Originally Posted by ajsalida

I remember seeing that episode when it first came out and thought it sucked. Anyway I think you are right about what is happening, however in that vid even if the front were locked it still would have slid down wet grass on a steep hill, as would any 4x4 with center dif locked up and those tires.

So maybe the simplest explanation is the summer tires + steep hill + ice, and maybe something happening with temps overnight dropping low enough to freeze and start a slide. IOW has nothing to do with AWD or front axle not locking up.

rant: I really hate "journalists" who try to make whatever personal point about something by distorting facts and presenting "evidence" like the video above. Put some real off road tires on an X6 it would do fine up that particular hill, even though it was never meant to be a Land Rover or have that capability. Might as well complain an AWD 911 turbo does poorly off road with race slicks on. The AWD on the X6 is not meant for Jeep trails or Paris-Dakar.

I think tires are the problem in the video and this icy hill issue, the general publics total lack of knowledge about what the correct tires are for situation. Really gets to me. Like when I pull and an x6 on summer performance run flats out of a snowy ditch with my jeep equipped with snow chains and the x6 owner didn't understand why he could'ent get to the up the hill to the skii ticket office.

[rosica]

Originally Posted by adidoman

I may to try that when it snows next. I'm not going to put winter tires on yet till I figure out the cause, and if it's just the tires it's an easy fix

Given the information I think tires are the problem you can test the parking brake by putting the car in park setting the hand brake jacking up the rear (chocking the front tires) you can test the hand brake by trying to spin the rear wheels they shouldn't move at all. I believe tires are the problem because in park with the hand brake on the only way to slide down the hill is to have 3 tires slide both rear and one front spinning in the opposite direction of the tire on the other side (due to the differential)

[ajsalida]

Originally Posted by rosica

I think tires are the problem in the video and this icy hill issue, the general publics total lack of knowledge about what the correct tires are for situation. Really gets to me. Like when I pull and an x6 on summer performance run flats out of a snowy ditch with my jeep equipped with snow chains and the x6 owner didn't understand why he could'ent get to the up the hill to the skii ticket office.

LOL you would not believe how often that happens (or maybe you would) up here in the high rockies. AWD does not repeal laws of physics, esp when you still have summer tires on. Lot of bent up Audis, Range Rovers, X5's, etc with out of state plates at the bottom of ravines etc.

Total mayhem around here during holidays, like now and today a blizzard is blowing in just in time for xmas. We are close to Wolf Creek ski area so kind of remote. But sometimes if they made it here thru bad weather Darwin has weeded out quite a few along the way.

[rosica]

Originally Posted by ajsalida

LOL you would not believe how often that happens (or maybe you would) up here in the high rockies. AWD does not repeal laws of physics, esp when you still have summer tires on. Lot of bent up Audis, Range Rovers, X5's, etc with out of state plates at the bottom of ravines etc.

Total mayhem around here during holidays, like now and today a blizzard is blowing in just in time for xmas. We are close to Wolf Creek ski area so kind of remote. But sometimes if they made it here thru bad weather Darwin has weeded out quite a few along the way.

Even on the east coast my tow strap gets lot use in winter (last year x6/crv/subaru's/many fwd's) last season I had my own interesting experience in a rental impala returning from Breckinridge.

[ajsalida]

Originally Posted by rosica

Even on the east coast my tow trap gets lot use in winter (last year x6/crv/subaru's/many fwd's) last season I had my own interesting experience in a rental impala returning from Breckinridge.

Yeah. What is weird is even the big rig semi drivers are often clueless. Last week guy tried to get away without chaining up (chains laws were in effect), jack knifed at the absolute most dangerous part of the pass, blocked road for hours. Lots of them either lose brakes or have improper chains/tires etc. or just too much speed even with everything right. Many go over the Big Edge (and usually die) or miss the emergency ramps and crash/flip into rock walls etc. Total mayhem. Have come across semis in process of jack knifing across my lane several times, that will wake you up fast.

Add to that the tourists careening very which way in a hurry to get to the slopes or get back down, and you must be on your toes at all times. Who knows what comes barreling out of the blizzard down at you, tourist going backwards, semi jack knifing, or a train of snow plows...

I came around the big dangerous hairpin two seasons ago in a blizzard, going up the mountain, steepest point of ascent. Near zero viz. It was 2 lanes up and one down at that point. Barely missed her, lady parked her SUV smack in the middle of the road on top of the yellow lines (if you could see them) calmly out of the car scraping her windshield off. Honked at her rolled down the window and told her to get the F out of the road. Mile further up coming down several big snow plows blasting along, with a big train of traffic stacked up behind them. No idea how that ended, was gone by the time I came back down the mountain.

Anyway it's that time of year again. BTW I drive my 4x4 Tacoma on days like this.

[adidoman]

Originally Posted by ajsalida

I remember seeing that episode when it first came out and thought it sucked. Anyway I think you are right about what is happening, however in that vid even if the front were locked it still would have slid down wet grass on a steep hill, as would any 4x4 with center dif locked up and those tires.

So maybe the simplest explanation is the summer tires + steep hill + ice, and maybe something happening with temps overnight dropping low enough to freeze and start a slide. IOW has nothing to do with AWD or front axle not locking up.

rant: I really hate "journalists" who try to make whatever personal point about something by distorting facts and presenting "evidence" like the video above. Put some real off road tires on an X6 it would do fine up that particular hill, even though it was never meant to be a Land Rover or have that capability. Might as well complain an AWD 911 turbo does poorly off road with race slicks on. The AWD on the X6 is not meant for Jeep trails or Paris-Dakar.

The only problem is that I didn't have a problem staying on a driveway in similar tires with a 1 series of mine and now it's doing is with the xDrive.

[adidoman]

So it snowed enough last night to do a little text. I marked chalk on the wheels and lines in the snow and when I was taking pictures the car slid down right in front of me. The rear tires locked up and were sliding down while the front moved.

I tried the test again this time really cranking up on the handbrake and it still slid down, same results taking a little longer this time. I would think the handbrake would stop the front wheels from rotating, or am I wrong?

[bd5400]

Originally Posted by adidoman

I tried the test again this time really cranking up on the handbrake and it still slid down, same results taking a little longer this time. I would think the handbrake would stop the front wheels from rotating, or am I wrong?

It would not stop the front wheels from rotating, only the rear.

[GB-335xiCoupe]

^^^ Yep hand brake only locks the rear wheels... And not very well at that...

[critical05]

Originally Posted by GB-335xiCoupe

^^^ Yep hand brake only locks the rear wheels... And not very well at that...

no the OP said the rear wheels were locked up.

I assume the additional weight of the XI offsets the friction coefficient of the tires and that's why it never happened with the 1 series.

Winter tires, wheel chock or new driveway with rougher texture.

[rosica]

Originally Posted by critical05

no the OP said the rear wheels were locked up.

I assume the additional weight of the XI offsets the friction coefficient of the tires and that's why it never happened with the 1 series.

Tire width would factor into cof. also.

[ajsalida]

Did the 1 series have same type of tires?

edit: btw I don't think any AWD car/suv locks up the transfer case in Park. And no 4wd (like a pickup) would unless it is left in 4wd. However the BMW is basically a RWD car with a TC tacked on. In Park the dominant wheels are locked up, in this case rears leaving front to spin freely. In a FWD dominant AWD car, like many Audis, the front axle will lock up in Park, but the parking brakes in either FWD or RWD will still be the rears. So an Audi may appear to lock all 4 wheel in park with the e-brake on, but in reality front is locking from the tranny and rear is the brake. Without the brake rears would roll freely.