[Billfitz]

I've driven through 6 to 8 inches of unplowed snow no problem, but I wouldn't try it with a foot, not so much being concerned with how my car will handle it than how every other vehicle won't. Even when we get four inches the roadsides are littered with SUVs whose drivers think that AWD will handle anything. It won't.

[CincyBearcats]

Originally Posted by Billfitz

I've driven through 6 to 8 inches of unplowed snow no problem, but I wouldn't try it with a foot, not so much being concerned with how my car will handle it than how every other vehicle won't. Even when we get four inches the roadsides are littered with SUVs whose drivers think that AWD will handle anything. It won't.

Good to know! And I know what you mean about others on the road. Luckily, our roads tend to be fairly empty. The F31 is replacing an '02 WRX, which was an absolute tank in the snow with snow tires. Hoping that the F31 is also very capable.

P.S. Thanks for answering my various questions across the forum this morning!

[thisismikeyb]

Originally Posted by CincyBearcats

New F31 owner here. Plan to use it to get to skiing on deep days, and the roads in NM are often slow to get plowed. I am often forced to drive through a foot of snow. I will add snow tires for sure, but what LSD do you recommend?

If I'm honest, I'm not super familiar with the xDrive system. I assumed that it has open front, center, and rear diffs and uses electronically controlled braking to assist with loss of traction.

I'm just referring to having an LSD in general. I sourced the M-Performance implementation which is a clutch based system. Unfortunately, there are so few people that added an LSD to their xDrive F30's.

xDrive uses a transfer case that is electronically controlled to route power to the front wheels, I believe it has 40/60 torque split normally, and will lock at 50/50 for traction limited environments, and be 0/100 under higher cruising speeds. I've noticed it feeling more RWD at this point and wish there was a way to monitor the lock up percentage of the transfer case in real time.

[johnung]

Originally Posted by thisismikeyb

I'm just referring to having an LSD in general. I sourced the M-Performance implementation which is a clutch based system. Unfortunately, there are so few people that added an LSD to their xDrive F30's.

xDrive uses a transfer case that is electronically controlled to route power to the front wheels, I believe it has 40/60 torque split normally, and will lock at 50/50 for traction limited environments, and be 0/100 under higher cruising speeds. I've noticed it feeling more RWD at this point and wish there was a way to monitor the lock up percentage of the transfer case in real time.

I have had many different cars with AWD. IMO the BMW XDrive is the best. Other systems are primarily 2WD with the other axle partially kicking in when needed. BMW does a tremendous job of distributing power to all four wheels. Driving my XDrive is more fun than any other car I've ever had.

Second place is probably the 1983 (first year in US) VW GTI 5-speed that I modded and flogged around the streets. Not the power of the BMW, but still a very high fun quotient.

The aftermarket M Performance LSD was built primarily for RWD guys who tracked their cars. Discounted they cost $2,300 plus about $600 for installation.

In 2019 BMW suddenly held a worldwide fire sale for $600 on the MP LSD for the F30 335i/ix Automatic Transmission model. So there are many of those models on the road with MP LSD's.

The stock F30 uses an electronic system that measures slippage at each rear wheel. If it senses >30% slippage at a wheel it has the ability to apply the brake at that wheel. I believe it can even cut throttle if rear wheel slippage is too high.

Note: Cars that experience greater than normal rear wheel slippage can result in extra rear brake wear.

The M Performance LSD is a mechanical system. It kicks in at 1% slippage at a rear wheel and disengages at 19%. When it senses slippage at one rear wheel it transfers power to the other wheel than has traction.

It's a quite ingenious system. The standard electronic system and the mechanical LSD work seamlessly together without either of them "knowing" about the other's existence. There is no overlap. So the MP LSD is installed and no programming or coding is needed at all.

I noticed the MP LSD immediately the first time that I entered a curve. The car just locked in and I was able to quickly power into and through the turn. Apparently with the stock differential, there must be a certain amount of slippage at the rear wheels, up to 30% when the electronic system would kick in. That all goes away with the MP LSD. It feels like I have more power into curves because the LSD is putting more power down to the rear tire that has the most traction.

There was an incident where I really appreciated the MP LSD. I entered a long circular curving on-ramp onto an interstate highway. I was going normal speed when a Camaro flew up onto my rear bumper. I nailed the gas and blew way ahead of him in the first half of the curve, but as I accelerated into the final part of the curve, my outside tires hit a heavy patch of gravel that had accumulated. Rather than slide off the road, I could actually feel power go to my inside rear tire, so I was able to just power out of it onto the highway straightaway. The Camaro must have been impressed. When he caught up later he rolled down his window and gave me a first pump.

[CincyBearcats]

Thanks for the very detailed responses! I have much to learn. It sounds like I need to keep an eye out for an M Performance LSD. $600 is an amazing deal if they can still be found at that price point.

[johnung]

Originally Posted by CincyBearcats

Thanks for the very detailed responses! I have much to learn. It sounds like I need to keep an eye out for an M Performance LSD. $600 is an amazing deal if they can still be found at that price point.

Sorry they sold out worldwide in a few months back in 2019 and they don't make it any longer for the 335i/435i automatic transmission cars. But they still make them for other models at $2,300. Here's the link to what's available

https://www.getbmwparts.com/c-differentials-92

[thisismikeyb]

Originally Posted by CincyBearcats

Thanks for the very detailed responses! I have much to learn. It sounds like I need to keep an eye out for an M Performance LSD. $600 is an amazing deal if they can still be found at that price point.

Looking at bmwparts.com, the rear diff on your car should be part number 33-10-7-603-747, while this would have been the same rear diff I would have had if my car was a made after 03/2014, my car has a production date of 06/2013 resulting in a different part number, 33-10-7-603-748, which at the time was the exact same part that was installed on the 35 series cars, and is what allowed me to swap the M Performance LSD into my 328i xDrive.

What the differences between the two are I could not tell you. Maybe FaRKle! would know? You will most likely have to go the Diffsonline route as well if you really want to get a rear LSD for your car.

[bmw777]

Hi, I just got 328xi.
Could you please tell me about F30 xdrive with All Season tires.
What situation need to be put snow chains on tires?

Thank you

[Billfitz]

USA as your location isn't specific enough for anyone to say.

[bmw777]

Originally Posted by Billfitz

USA as your location isn't specific enough for anyone to say.

I'm in Oregon
Not offent to see snow but my apartment is on the hill....
I never know about snow chains, I will research more than this.
Thank you

[Ennoch]

The BMW X drive system is the typical modern slightly wanky pretend 4wd system aimed to put power down on wet roads but it does do a passable job in day to day driving. The rear bias is quite good fun when you want to do that in the snow but when the snow gets proper deep it does lack the strength of a proper permanent 50/50 which has a centre diff. The transfer case is the biggest issue in the BMW system because it doesn't have a diff in it, hence all the blown units.

As long as the snow isn't sticky and wet though then you should be fine in deep snow, just as long as you don't actually beach it. I've got Sottozero's on mine and had it up to 18-24" powder with it pouring over the bonnet and it was fine. The biggest issue was the narrow 10ft wide ribbon of single track tarmac that was twisty and had ditches either side.

[johnung]

Originally Posted by bmw777

Hi, I just got 328xi.
Could you please tell me about F30 xdrive with All Season tires.
What situation need to be put snow chains on tires?

Thank you

You are going to get better winter road information by talking to folks locally. There are regional groups on Bimmerpost and probably a number of local BMW Facebook groups. Ask people in your neighborhood about the winters, look at what cars they drive, ask about their experiences. Stop at some tire shops but realize that their advice is about trying to sell you something.

I live in NJ/Philadelphia so I have good winter advice for people living here. But my family in Vermont have a much different winter road experience. They also have local regulations about the use of chains and studded tires.

[Billfitz]

Originally Posted by bmw777

I'm in Oregon
Not offent to see snow but my apartment is on the hill....
I never know about snow chains, I will research more than this.

I live in New Hampshire, where we get snow from October through April. I drove to my ski shop in the mountains 5 days a week for 25 years, in all weather conditions. I never missed a day, and never had chains. Never had AWD either, I got my xDrive after I retired.

[MechEngineer]

I legitimately have more fun driving in the snow than in the dry in my car ( 15' M235XI). I used to live in Michigan and I've taken a ski trip to the mountains in Colarado.

I'm running X ice 3 on 17's and at normal speeds i can barely even tell I'm on snow. In Sport+ or DCS off it's very easy to get the back end to step out, but the car effortlessly levels out if you give it gas. And I don't have the LSD, though that's down the line.

[Bori_san]

I will test my xDrive in Poland now, we will see

[mobbinthesteez]

In Alaska and coming from a Subaru I can say the Xdrive is very capable. I am having the M Performance LSD installed this month tho. Can't Hurt!

[cfm56d7b]

Originally Posted by johnung

I have had many different cars with AWD. IMO the BMW XDrive is the best. Other systems are primarily 2WD with the other axle partially kicking in when needed. BMW does a tremendous job of distributing power to all four wheels. Driving my XDrive is more fun than any other car I've ever had.

Second place is probably the 1983 (first year in US) VW GTI 5-speed that I modded and flogged around the streets. Not the power of the BMW, but still a very high fun quotient.

The aftermarket M Performance LSD was built primarily for RWD guys who tracked their cars. Discounted they cost $2,300 plus about $600 for installation.

In 2019 BMW suddenly held a worldwide fire sale for $600 on the MP LSD for the F30 335i/ix Automatic Transmission model. So there are many of those models on the road with MP LSD's.

The stock F30 uses an electronic system that measures slippage at each rear wheel. If it senses >30% slippage at a wheel it has the ability to apply the brake at that wheel. I believe it can even cut throttle if rear wheel slippage is too high.

Note: Cars that experience greater than normal rear wheel slippage can result in extra rear brake wear.

The M Performance LSD is a mechanical system. It kicks in at 1% slippage at a rear wheel and disengages at 19%. When it senses slippage at one rear wheel it transfers power to the other wheel than has traction.

It's a quite ingenious system. The standard electronic system and the mechanical LSD work seamlessly together without either of them "knowing" about the other's existence. There is no overlap. So the MP LSD is installed and no programming or coding is needed at all.

I noticed the MP LSD immediately the first time that I entered a curve. The car just locked in and I was able to quickly power into and through the turn. Apparently with the stock differential, there must be a certain amount of slippage at the rear wheels, up to 30% when the electronic system would kick in. That all goes away with the MP LSD. It feels like I have more power into curves because the LSD is putting more power down to the rear tire that has the most traction.

There was an incident where I really appreciated the MP LSD. I entered a long circular curving on-ramp onto an interstate highway. I was going normal speed when a Camaro flew up onto my rear bumper. I nailed the gas and blew way ahead of him in the first half of the curve, but as I accelerated into the final part of the curve, my outside tires hit a heavy patch of gravel that had accumulated. Rather than slide off the road, I could actually feel power go to my inside rear tire, so I was able to just power out of it onto the highway straightaway. The Camaro must have been impressed. When he caught up later he rolled down his window and gave me a first pump.

This post brings back fond memories of my own 1984 VW GTI 5-speed and various Oettinger accessories.

[johnung]

Originally Posted by cfm56d7b

This post brings back fond memories of my own 1984 VW GTI 5-speed and various Oettinger accessories.

Oh wow, I had an '83 GTI. Black with a red interior. 5speed. Put an overdrive 5th gear in so it was less buzzy for my long work commute. Loved that car. Lots of fun! Every time that I see a little Mini I wonder if with a manual it would feel similar to throwing a GTI into corners.

[cfm56d7b]

johnung This world is too small. My GTI was _exactly_ the same except 1984 model year.

[cheseenlo]

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.

wow this is great

[tturedraider]

Originally Posted by cheseenlo

wow this is great

Yes, just to reiterate, xDrive (not to include the FWD based designs) has a default distribution of power front to rear of 40:60 and is capable of sending 100% of the torque to both the front and rear axles in an infinitely variable distribution and doing so instantaneously such that the changes in distribution are imperceptible.

Skyhigh’s posts are so full of incorrect, misinformation they really should be removed from this thread.

[Skyhigh]

Thank you. Except my posts are based on technical data and understanding, yours - on marketing material ignoring absolutely key terms like “virtually” and failing to apply technical interpretation.

Food for thought: In the case of a rear axle spinning, there is “virtually” no torque getting to it as you need traction for torque. The axle remains connected with 50:50 torque distribution mechanically, but this is how xDrive “virtually” achieves 100:0 distribution of the available torque (close to 0 being utilised in the rear axle) for a split second, until traction is reinstated. And this is greatly used by marketing for people with no technical insight or understanding.

xDrive as a system however CANNOT selectively send more than 50% to the front. This is mechanically impossible (fully closed transfer case clutch).

https://www.carblogindia.com/what-is-bmw-xdrive/

Quote from the above source which is apparently also “full of incorrect” (or simply written by people with basic understand of mechanics) …:

Using this setup, xDrive sends the torque between the front and rear axles, normally in a 40:60 ratio. However, the system can react in a split second, generally, one-tenth of a second, to redistribute up to 100% of the power to the either axles in case of detection of loss of traction by the car’s ABS (Anti-lock Brake System) or DSC (Dynamic Stability Control).

There’s a high-speed Electric Servo motor that turns an actuator disc to apply the wet clutch. A catch here is that since the rear driveshaft is hard-coupled to the transmission output, 100% torque can be transferred to the front axle is achieved only when the rear wheels have a lack of traction. xDrive works in tandem with the car’s ABS and DSC systems. In case there’s a loss of traction even after the xDrive comes into play, the DSC automatically applies brakes to individual wheels in order to establish traction and introduce stability.

Prove me wrong with a technical explanation about how 100% torque can be (selectively, not virtually) sent to the front or let’s agree to disagree and you keep dreaming.