[BingoTheClown]

Last year I purchased a 2018 440i xDrive GC. This is my first winter with it. Previously I have watched lots of youtube vids about xDrive in the snow. I was very excited to see how well it seemed to handle in this weather.

Although it has been brutally cold here in upstate NY, we have only had 2 small snow storms where I live. First one was just a bit more than a dusting of snow on the roads. And my 440i was all over the place. Even slow turns the rear would slip out.

Second storm: just about 1.5" on the ground. Roads semi-plowed and slushy but not icy. Again - my 440i was awful on the roads. Really had a hard time keeping control, even slow driving.

Now, I have to put things in perspective. I drove a huge Escalade for many years. Obviously there is a big big difference in snow handling. But I didn't expect it to be this awful for AWD car.

Second - I have the runflats. and YES - this is probably the issue at hand. Better tires will improve things. But, the RF's were brand new and lots of tread. I don't love the RF's, for sure. But I want to get my money out of them before I upgrade my tires. So, I will push through this winter and replace them before next winter. Hopefully that helps - but I still feel a bit lackluster over xDrive AWD.

[HighlandPete]

Originally Posted by BingoTheClown

Second - I have the runflats. and YES - this is probably the issue at hand. Better tires will improve things. But, the RF's were brand new and lots of tread. I don't love the RF's, for sure. But I want to get my money out of them before I upgrade my tires. So, I will push through this winter and replace them before next winter. Hopefully that helps - but I still feel a bit lackluster over xDrive AWD.

What tires are you running? Summer, All-Season or Winter tires?

[Polo08816]

Originally Posted by BingoTheClown

Last year I purchased a 2018 440i xDrive GC. This is my first winter with it. Previously I have watched lots of youtube vids about xDrive in the snow. I was very excited to see how well it seemed to handle in this weather.

Although it has been brutally cold here in upstate NY, we have only had 2 small snow storms where I live. First one was just a bit more than a dusting of snow on the roads. And my 440i was all over the place. Even slow turns the rear would slip out.

Second storm: just about 1.5" on the ground. Roads semi-plowed and slushy but not icy. Again - my 440i was awful on the roads. Really had a hard time keeping control, even slow driving.

Now, I have to put things in perspective. I drove a huge Escalade for many years. Obviously there is a big big difference in snow handling. But I didn't expect it to be this awful for AWD car.

Second - I have the runflats. and YES - this is probably the issue at hand. Better tires will improve things. But, the RF's were brand new and lots of tread. I don't love the RF's, for sure. But I want to get my money out of them before I upgrade my tires. So, I will push through this winter and replace them before next winter. Hopefully that helps - but I still feel a bit lackluster over xDrive AWD.

xDrive is fine. Your tires are the culprit.

[thisismikeyb]

xDrive is great with a good set of winter tires, it's also more fun with a proper LSD in the back.

[Billfitz]

With the stock Conti run flat all seasons my xDrive was better in snow than any 2wd car I ever owned, be it FWD or RWD, even with winter tires. I've got to figure you have summer tires or the world's worst all seasons. Last fall I put on Michelin Cross Climate 2 all seasons and it's even better.

[Th3Walrus]

xDrive/AWD only makes a difference when accelerating. Steering & braking, it's all the tires. I would never run all seasons where I am in the winter, and I would also never run all seasons on a performance car in the summer.

[johnung]

Originally Posted by BingoTheClown

Last year I purchased a 2018 440i xDrive GC. This is my first winter with it. Previously I have watched lots of youtube vids about xDrive in the snow. I was very excited to see how well it seemed to handle in this weather.

Although it has been brutally cold here in upstate NY, we have only had 2 small snow storms where I live. First one was just a bit more than a dusting of snow on the roads. And my 440i was all over the place. Even slow turns the rear would slip out.

Second storm: just about 1.5" on the ground. Roads semi-plowed and slushy but not icy. Again - my 440i was awful on the roads. Really had a hard time keeping control, even slow driving.

Now, I have to put things in perspective. I drove a huge Escalade for many years. Obviously there is a big big difference in snow handling. But I didn't expect it to be this awful for AWD car.

Second - I have the runflats. and YES - this is probably the issue at hand. Better tires will improve things. But, the RF's were brand new and lots of tread. I don't love the RF's, for sure. But I want to get my money out of them before I upgrade my tires. So, I will push through this winter and replace them before next winter. Hopefully that helps - but I still feel a bit lackluster over xDrive AWD.

It's definitely your tires. Why not just get winter tires now and then put your runflats back on in the Spring? The winter tires that I would recommend are Michelin X-Ice SNOW (great on moderate snow, ice, black ice, and quiet too) and Blizzak WS90 which are great in heavy snow but they can be noisier.

I have Michelins and they drive on Black Ice like it's dry pavement.

You will see a tremendous difference with winter tires. Why wait? It's a safety issue. You can order from TireRack and have them installed in a few days.

Hope this helps!

[Skyhigh]

Sounds like you have an issue with your tires... (as others pointed out).
You didn't specify what they are? Run-flat or go-flat, that's not the issue - Most BMWs come with Run-flats.

Put proper winter tires on. I'm surprised all-seasons tires are still popular in the states - no one uses those in Europe any longer, as they are compromised both in the summer and in the winter, with very little economical benefit for a car which is driven regularly.

I have been driving in the snowy mountains, no problems whatsoever. The only thing I noticed is that when I intentionally provoke it (hard acceleration in the snow), the rear does go out to the side for a second or two (since it is rear-biased vehicle... I guess), but then xDrive puts me back on track. Very happy with it.

[CrimsonMoonLight72]

Originally Posted by BingoTheClown

Last year I purchased a 2018 440i xDrive GC. This is my first winter with it. Previously I have watched lots of youtube vids about xDrive in the snow. I was very excited to see how well it seemed to handle in this weather.

Although it has been brutally cold here in upstate NY, we have only had 2 small snow storms where I live. First one was just a bit more than a dusting of snow on the roads. And my 440i was all over the place. Even slow turns the rear would slip out.

Second storm: just about 1.5" on the ground. Roads semi-plowed and slushy but not icy. Again - my 440i was awful on the roads. Really had a hard time keeping control, even slow driving.

Now, I have to put things in perspective. I drove a huge Escalade for many years. Obviously there is a big big difference in snow handling. But I didn't expect it to be this awful for AWD car.

Second - I have the runflats. and YES - this is probably the issue at hand. Better tires will improve things. But, the RF's were brand new and lots of tread. I don't love the RF's, for sure. But I want to get my money out of them before I upgrade my tires. So, I will push through this winter and replace them before next winter. Hopefully that helps - but I still feel a bit lackluster over xDrive AWD.

The one thing I always wondered about is all xdrive systems equal as in is the xdrive system in a car like a 340i the same system as xdrive in a more dedicated suv like the x3 or x5 ? I can vaguely remember a SA telling me that the xdrive in bmw suv’s were more effective than the xdrive in the bmw sedans and coupes. That would be weird if so.

[Billfitz]

Sounds like that SA was trying to up sell you.

[HighlandPete]

Originally Posted by CrimsonMoonLight72

The one thing I always wondered about is all xdrive systems equal as in is the xdrive system in a car like a 340i the same system as xdrive in a more dedicated suv like the x3 or x5 ? I can vaguely remember a SA telling me that the xdrive in bmw suv’s were more effective than the xdrive in the bmw sedans and coupes. That would be weird if so.

From the technical data, no, not all xDrive systems are the same these days. Depends on models and performance, but some are more RWD biased, for more of the time.

Comments such as the following... in G30 data, "The torque distribution towards the front wheels can be completely cut-off in driving situations where all-wheel drive is not needed". Another example is M-Performance models, also set up with more rear wheel bias.

Doesn't take much to imagine the thresholds for torque transfer are therefore different.

[HighlandPete]

Originally Posted by Billfitz

Sounds like that SA was trying to up sell you.

It is difficult keeping up with how BMW are modifying xDrive in latest models.

The older understanding is not always applicable anymore.

[Skyhigh]

Originally Posted by HighlandPete

Comments such as the following... in G30 data, "The torque distribution towards the front wheels can be completely cut-off in driving situations where all-wheel drive is not needed".

That's no different for the F series.

xDelete documentation does however also mention different default torque distribution depending on the model and even on the engine within the same model.

The technology behind it is the same though. No reason to think SUVs are more "effective" even assuming a different bias.

[HighlandPete]

Originally Posted by Skyhigh

That's no different for the F series.

xDelete documentation does however also mention different default torque distribution depending on the model and even on the engine within the same model.

The technology behind it is the same though. No reason to think SUVs are more "effective" even assuming a different bias.

Thresholds for interventions is where the differences could be programmed in and felt by users.

[CrimsonMoonLight72]

Originally Posted by HighlandPete

Thresholds for interventions is where the differences could be programmed in and felt by users.

Yes in that regard there probably are differences....the thing that drives me nuts in when after driving in wet packed snow for a bit the amount of snow that sticks in clumps in wheel well. It’s gets so bad that I worry about the snow pushing into and jamming wheels as I’m driving. I’ve pulled over many times just to break apart the snow and ice that collects in wheel well.

[Billfitz]

The ATC 35L transfer box was used in 1 through 6 series cars. The ATC 45L was used in the X3 through X6. Physically they're different, which is logical considering the differences in the chassis they go into. According to BMW how they operate is the same, both with a normal 40:60 front/rear axle bias, able to allocate up to 100% of its power to one axle. There could be programming differences, but I wouldn't expect them to be significant. It's not like an X3-6 is intended as an off-road vehicle. They're still soccer mom machines.

[Skyhigh]

Originally Posted by Billfitz

According to BMW how they operate is the same, both with a normal 40:60 front/rear axle bias, able to allocate up to 100% of its power to one axle.

Important clarification: Not to any "one" axle, 100% can only go to the rear! Front maximum is 50%!
So anything from 50:50 to 0:100 with default at 40:60.

(According to xDelete guys however, the default bias varies from model to model end even within the same model.)

[HighlandPete]

Originally Posted by Skyhigh

Important clarification: Not to any "one" axle, 100% can only go to the rear! Front maximum is 50%!
So anything from 50:50 to 0:100 with default at 40:60.

(According to xDelete guys however, the default bias varies from model to model end even within the same model.)

I assume you mean when the coefficient of friction is the same on both axles. When on ice at the rear, for example, up to 100% of torque can be transferred to the front axle.

BMW do state for some models the default bias is 50:50, not the 40:60 that used to be the normal default.

[Skyhigh]

No, it cannot! Mechanically, with the xDrive system in our cars, the maximum torque which can be distributed to the front axle is 50% and max to the rear - 100%. When the TCU clutch is open - 100% goes to the rear, when it is fully closed - 50% front and 50% rear. Anything inbetween is also possible. but the rear cannot be less than 50% and the front cannot be more than 50%.

http://www.awdwiki.com/en/xdrive/ :

"Proactive automatic all wheel drive system. The rear wheels are powered at all times. Torque can be transferred to the front wheels via electronically controlled multi plate clutch that is located in the transfer case. XDrive does not have a center differential. Most of the time, the clutch is partially locked and power is transferred to both axles in proportion 40/60 front to rear. The power distribution can be altered to continuously variable levels (from 50/50 to 0/100). For example, when driving at high speed, or when parking, the clutch is disengaged and all power goes to the rear wheels.

XDrive is linked to DSC (Dynamic Stability Control) - when the vehicle understeers, the clutch is disengaged thus transferring more torque to the rear wheels (10/90 torque split). When oversteering is detected, the clutch locks fully transferring more power to the front wheels (50/50 torque split)."

Newer BMW models like the 1-Series and some X models have a completely different AWD system (more like in Audi) which allows full-FWD by default.

For F-series, the default claimed by BMW is 40:60.

[chowser51]

Yeah what tires do you have?
If you don’t want a dedicated setup then get some of the new all weather tire like the CrossClimate2s.

But i would personally do a dedicated winter and summer setups.

[HighlandPete]

Originally Posted by Skyhigh

No, it cannot! Mechanically, with the xDrive system in our cars, the maximum torque which can be distributed to the front axle is 50% and max to the rear - 100%. When the TCU clutch is open - 100% goes to the rear, when it is fully closed - 50% front and 50% rear. Anything in between is also possible. but the rear cannot be less than 50% and the front cannot be more than 50%.

But that is only part of the function. Get on slippery surfaces and all available torque can go to the front. Also more than 50% of torque can be applied to the front axle in oversteer situations.

BMW state:

When the multi-disc clutch is fully engaged, the front and rear axles turn at the same speed. Driving torque distribution (front/rear) is based on available traction at each axle. For example, when traction is identical on the front and rear axles and a driver accelerates from a stop in first gear at full throttle, the rear axle is capable of sustaining greater driving torque as the vehicle weight shifts from the front to the rear.

Another example is when the front axle is on a high traction surface and the rear axle is on ice. In this case, virtually 100% of the available driving torque is transmitted to the front axle. Based on available traction, virtually no driving torque can be supported by the rear axle. Obviously, when more driving torque is transmitted to the front axle, driving torque on the rear axle is proportionally reduced due to lack of traction.

An exception is made when the front axle is on a surface with a high friction coefficient and the rear axle is on black ice, for example. In this case, almost 100% of the available drive torque is transmitted to the front axle since almost no torque can be supported at the rear axle.

BMW illustrations show that more than 50% of the available torque is transmitted to the front axle, in slippery and oversteer conditions.

[CrimsonMoonLight72]

Originally Posted by HighlandPete

But that is only part of the function. Get on slippery surfaces and all available torque can go to the front. Also more than 50% of torque can be applied to the front axle in oversteer situations.

BMW state:





BMW illustrations show that more than 50% of the available torque is transmitted to the front axle, in slippery and oversteer conditions.

What about side to side traction? I have this big ice spot on the side of my street and if I go over that ice spot ONLY with driver side wheels, either front or rear driver side wheels, what should the PASSENGER side wheel(s) do on the dry pavement as the driver side wheels or wheel is spinning on the ice? Do the passenger side wheels spin at same rpms on the dry pavement as the driver side wheels that are spinning on the ice? Or do they turn at a slower rpm than the spinning opposing wheels over the ice?