[Zooks527]

Originally Posted by pikcachu

your are so much fun

And the little pikachu abandons the field and runs away.

[RPM90]

Originally Posted by Zooks527

Ah, the Wikipedia xDrive article. Interesting piece. In fact, if you look, you'll find that I was one of the contributors.

Still, I've never been a big believer in Wikipedia as proof anything, but hey, what the hell, I need a laugh this morning.



Or not. Your choice.

Hi guys.
I don't mean to throw more fuel on the fire, so take this as commentary and not argument.
I've read posts by both of you on this subject.
After reading what the wiki says about X-drive and what I know about it, meaning I'm no complete expert.

Xdrive uses a clutch in order to transfer power/torque to the front or rear, and it can transfer up to 100% of available power to either the front or rear axles.
So this means that all available traction/motion power can be sent to the front or rear axle. That's a positive improvement over the last system.

Now the question of delivering that power left or right, on either axle, seems the crux of the arguuu...errr...discussion.
From what the systems description says the Xdrive system, working with the DSC system, can modulate/brake a tire that is slipping, thus controlling that wheel spin and LOSS of traction. That individual braking application helps to stop tire spin and thus the loss of it's traction to help stabilize the chassis in a turn, because the tire is no longer slipping in it's travel arc.

As for the power, the system can not apply all available power to the wheel that is not slipping. Why? Because the system uses an 'open differential'. One of the effects of an open differential is that as a tire loses traction even more torque goes to that tire, which has already lost traction. This is not a good thing because in a turn the tire that is already slipping is now being given even more power and spinning even more, and that means greater potential for loss of control and definitely no power being transferred to forward motion.

This is where DSC comes in. It can sense a tire losing grip and apply braking to that individual tire. This helps that tire to regain it's traction and stabilize the car in the turn. Now, as another effect of braking a slipping tire, on an open differential, it can be argued that the power that would have gone, and been lost, to spinning the traction-less tire is diverted back towards the tire that has grip. How? Because the open differential is "sensing" that the once spinning tire has regained it's traction and thus no longer needs to keep feeding power to the slipping tire.

Yet, we still have a net loss in available torque with this system because it can not apply all of the available power to the road via the tires.
There is loss in power as the tire loses traction and thus more power is applied to that tire. Once the DSC senses the slipping tire it will brake that tire and some available power will also come back to the tire with grip. But, at the same time the brakes are fighting the torque being applied to the tire losing grip. That's where there is power loss, or power to motion transfer loss.

DSC can only brake the tire that is losing traction, and as it's losing traction it is wasting power that could have gone to forward motion if the power remained coupled to the tire with traction, as would be the case with an LSD. Since that tire is slipping and can't provide any torque to motion, that power is lost as the brakes are applied.
For the tire that has traction the available power is somewhat returned to or maintained. Can we say that by braking the slipping tire the open differential is thus allowing some available power to go the tire with grip?
I do think a case can be made for that, because, if there were no individual braking to the slipping tire even more power would be lost as the open differential sends even more power to the slipping tire.
However, this is not the same as a system than can direct the available power to the tire with grip. Xdrive does not have that ability as it does not have LSD to do that function. The DSC is a cheaper way to mimic what an LSD would do.
If Xdrive had a way to split available torque between the wheels without having the brakes fighting against the torque, then it could maximize power transfer to the road via the tire that is gripping.

I think pickachu is making the point that Xdrive can not deliver maximum power to the tire that has grip due to having open differentials. The system can only brake the tire that has lost grip, and in that process that torque/power is lost in the process.
Still, by braking the spinning tire the open differential does allow some of the power, that would be wasted if that tire continued to spin, to be transferred back to the tire with grip. In effect the system does transfer some power back towards the tire that is not slipping.
However, it doesn't do it as effectively as a system that has the differentials to do it properly.

I think you both have valid points.

Is this system a bad thing? It could be if you are racing as you are not effectively able to transfer all available power to forward motion and thus you are effectively going slower than you could be if the power could be transferred to the tire/tires that have grip.
But, for everyday driving the system is effective because it can provide individual tire braking to get tire spin under control and thus allowing the slipping tire/s to regain their traction. And more so, it helps to stabilize the car through the turn giving greater safety.

The system wasn't designed for best possible performance, but it allows for greater safety and control. As for being able to brake individual tires that is great even for non AWD cars.

I may have repeated myself somewhere above, but I've written too much and don't want to reedit yet again.

[pikcachu]

Originally Posted by Zooks527

And the little pikachu abandons the field and runs away.

i already showed you were wrong... just give it up
"xdrive can't split torque individually without having DSC apply brakes".

Your were right about the M235xi talking LSD which is the first xdrive car ever to allow it.... I'll give you credit for that...

[RPM90]

Originally Posted by Sportstick

With equivalent tires, the AWD winter advantage is limited to getting moving. Braking and turning to stop or avoid safely are a function of the tires, hopefully dedicated winter tires. AWD with winters >RWD with winters>>>AWD with all season>RWD with all season. Modest difference between cars with similar tires; large difference between tires.

I agree that tires are VERY important in traction limited conditions more so than which wheels are driven. There is only one thing that connects the car to the road and that is the small patches of tire mounted to the car.
This is especially true for braking where the tire is THE deciding factor on whether you will stop or become an obstacle in the median facing the wrong side of the red light.

I would like to add on the question about overall handling in traction limited conditions.
In my experience AWD can, I say "can", have a slight advantage even while moving, meaning handling.
It's related to the advantage you cite, which is that AWD advantage is in "getting moving". I will assert that that AWD advantage can help one steer in low traction conditions.
After all this is why AWD is superior in dirt and rally racing, because it uses it's traction and acceleration advantage to pull the car into and through the turn.

When driving RWD on snow, even with snow tires, the rear end can more easily come around as that is the inherent nature of RWD, and why it's so fun as well. Also, in a turn the front tires can plow through or slide as they too have limited traction. In that situation you have to let up on the throttle or risk the rear end coming around. Also, you can't apply power to the front tires to get them to bite and pull the front back into the turn.
You have to let up on the power to allow the tires to regain grip and hopefully return to a safer path around a turn.

With AWD the acceleration advantage is also there while in motion to help turn the car in a turn. If the front starts to plow you can apply more power, which can help the tires bite and drive you into a safer arc around the turn.
As you apply more power the rear tires also drive slightly "around" so that you can rotate the car into the turn. You have to experience this to know that it is true.

Now I will say that this technique is best used by those who have experience in driving that way, which is to say that the general populace doesn't understand that AWD is not an excuse to drive crazily and think you'll be just fine because you have AWD.
The scariest and funniest thing I see in winter is the number of AWD cars in ditches or off the road because they think AWD is some magical bad weather solution allowing one to drive like an idiot in an AWD.

[RPM90]

Originally Posted by schybrid

I could give a crap about xdrive for winter or braking etc, all i want it for is droppin da hammer bouncing off redline as a red light ninja.

BTW, "bouncing off redline" is not the fastest way these modern turbo BMW's operate.
You'll know once you get your new AWD M235Xi, which is great choice imo.

[Zooks527]

Originally Posted by pikcachu

"xdrive can't split torque individually without having DSC apply brakes".

Not sure what you're quoting, but I'll go with it.


So you're saying one of 2 things:

(1) "xDrive can't split torque ... without DSC", the converse of which is therefore "xDrive can split torque ... with DSC". So, you've now conceded you can get an LSD in 2-series xDrive cars, xDrive can split torque, and xDrive uses the brakes to do so. What have you proved wrong?

or

(2) You think you've gone somewhere with the very early post about turning off DSC, and think the above validates that. However, the ADB-X version of the software used on an xDrive car doesn't disable the torque splitting function when DSC is turned off by the driver. So, even if DSC is off on an xDrive car, the differential braking function remains.


An old boss of mine once warned me about arguing with the dim, because they'll drag you down to their level and then wallow there. He had a point.

[Zooks527]

Originally Posted by RPM90

With AWD the acceleration advantage is also there while in motion to help turn the car in a turn. If the front starts to plow you can apply more power, which can help the tires bite and drive you into a safer arc around the turn.
As you apply more power the rear tires also drive slightly "around" so that you can rotate the car into the turn. You have to experience this to know that it is true.

Very true. Takes some practice to learn how to do it, but it's a useful feature once you know how. Still grossly dependent on tire selection (RWD with snows still beats AWD with A/S in just about any winter condition), but the ability to do this on an AWD car with snows can be startling to people who've never seen it.

[Turbo_435i]

Ok now that we got all the texhnical arguing out of the way,

Is awd better for acceleration and cornering , or rwd ?

[Legal Bill]

Originally Posted by schybrid

Ok now that we got all the texhnical arguing out of the way,

Is awd better for acceleration and cornering , or rwd ?

^That's some funny stuff right there.

[Cyberdemon]

Originally Posted by schybrid

Ok now that we got all the texhnical arguing out of the way,

Is awd better for acceleration and cornering , or rwd ?

AWD is better at everything. Buy the AWD car so we can delete this thread from existence.

[olaosunt]

Originally Posted by kdog26372

The point would be you want a car that drives about the same rain or shine. If you plan to tune the car even with a stage 1 you will fight for traction in 1st 2 gears with RWD while the AWD will just launch and go. That is unless you are the 1 guy on this forum that actually drives around with Mickey Thompson drag radials as his daily tire of choice.

.

Yes, that guy would be me

I don't want to think this is a "BMW thing" but I find it amusing that you think it odd for one to drive around on drag radials.

Of course you have to be sensible and on days when it rains I drive my Audi S4.I have a set of blizzaks for winter time on all my cars(except the mustang).

My Mustang makes 800 rwhp, runs the 1/4 in 10.3@138 through a manual, and can be safely driven on the street

with drag radias.







It has SLICKS on in the photo,nd NO I don't drive around on those as it

is not legal(although I know some people who do).


My point is, you chose a tire to match the purpose of your car,driving

style, weather condition and of course amount of rwhp and torque you make.

What is the point of moding and adding power if it all goes up in tire

smoke?..... bragging rights ?... or only all wheel drive cars should add

power because you cant drive around on drag radials(or whatever sticky tire

you choose).

YOU obviously wasted your money and time adding power to your RWD car if

all YOU did was spin the tires.May be YOU should have invested in drag

radials(and they cost less than AWD).

I am no red light warrior nor am I a road course hero( and I don't pretend to

be and have never been to one), but my M235 saw the drag strip regularly as I made sequential

changes to the bolt on's,tune,gas and finally tire(last change) in my quest

for an 11 second time slip.

If you want to truly test how fast your car accelerates, and not endanger any

one else(but yourself) in the process, the drag strip is the ONLY place to do

it.

I am certain even if you put drag radials on all 4 wheels of the X drive it is

not going to get a better a 60 ft. than 1.6, and by the 330 ft mark

the RWD drive car(with sticky tires) has already closed the gap AND will be

quicker to 60 mph(as it seems that is what many care about)..........



And lastly this fallacy that keeps getting

propagated (you parroted it here) about RWD with snows being better than AWD with all season. Absolute

nonsense.

I compared my Audi S4 with all seasons(I put snows on eventually) to the BMW with Blizzaks last winter and it was
no contest.
Like I said, before I suspect that is the main reason you switched to X drive, and not some" performance" reason like

you want others to believe.

[pikcachu]

Originally Posted by Zooks527

Not sure what you're quoting, but I'll go with it.


So you're saying one of 2 things:

(1) "xDrive can't split torque ... without DSC", the converse of which is therefore "xDrive can split torque ... with DSC". So, you've now conceded you can get an LSD in 2-series xDrive cars, xDrive can split torque, and xDrive uses the brakes to do so. What have you proved wrong?

or

(2) You think you've gone somewhere with the very early post about turning off DSC, and think the above validates that. However, the ADB-X version of the software used on an xDrive car doesn't disable the torque splitting function when DSC is turned off by the driver. So, even if DSC is off on an xDrive car, the differential braking function remains.


An old boss of mine once warned me about arguing with the dim, because they'll drag you down to their level and then wallow there. He had a point.

1 - you don't even know your logic:

"xDrive can't split torque individually ... without DSC", the converse of which is therefore "xDrive can split torque individually ... with DSC"
"In logic, the converse of a categorical or implicational statement is the result of reversing its two parts."
Converse would be "without DSC xdrive can't split torque individually"

2 - If you turn DSC off you get eDiff which will still brake individual wheels...

Had enough entertainment already keep arguing if you want..

[Turbo_435i]

Drag radials wear out too fast, fail

[kdog26372]

Originally Posted by olaosunt

Yes, that guy would be me

I don't want to think this is a "BMW thing" but I find it amusing that you think it odd for one to drive around on drag radials.

Of course you have to be sensible and on days when it rains I drive my Audi S4.I have a set of blizzaks for winter time on all my cars(except the mustang).

My Mustang makes 800 rwhp, runs the 1/4 in 10.3@138 through a manual, and can be safely driven on the street

with drag radias.







It has SLICKS on in the photo,nd NO I don't drive around on those as it

is not legal(although I know some people who do).


My point is, you chose a tire to match the purpose of your car,driving

style, weather condition and of course amount of rwhp and torque you make.

What is the point of moding and adding power if it all goes up in tire

smoke?..... bragging rights ?... or only all wheel drive cars should add

power because you cant drive around on drag radials(or whatever sticky tire

you choose).

YOU obviously wasted your money and time adding power to your RWD car if

all YOU did was spin the tires.May be YOU should have invested in drag

radials(and they cost less than AWD).

I am no red light warrior nor am I a road course hero( and I don't pretend to

be and have never been to one), but my M235 saw the drag strip regularly as I made sequential

changes to the bolt on's,tune,gas and finally tire(last change) in my quest

for an 11 second time slip.

If you want to truly test how fast your car accelerates, and not endanger any

one else(but yourself) in the process, the drag strip is the ONLY place to do

it.

I am certain even if you put drag radials on all 4 wheels of the X drive it is

not going to get a better a 60 ft. than 1.6, and by the 330 ft mark

the RWD drive car(with sticky tires) has already closed the gap AND will be

quicker to 60 mph(as it seems that is what many care about)..........



And lastly this fallacy that keeps getting

propagated (you parroted it here) about RWD with snows being better than AWD with all season. Absolute

nonsense.

I compared my Audi S4 with all seasons(I put snows on eventually) to the BMW with Blizzaks last winter and it was
no contest.
Like I said, before I suspect that is the main reason you switched to X drive, and not some" performance" reason like

you want others to believe.

Enjoy your Mustang. My point was many people tune, most don't run drag radials as daily driver on a BMW. Congrats that you do on your Mustang. Don't recall saying anything was "odd", just asked to be corrected if a large # of BMW owners here were running a tune and drag radials as their daily combo. I'm sure that's different on the Mustang/Camaro threads. Don't really care, enjoy your setup and I'll enjoy mine.

[kdog26372]

Also to Mustang guy, I don't care what others think and I've said numerous times enjoy what you have and each RWD and AWD has reasons to get and not get. Trying to say I've got some different agenda for why I chose AWD over RWD for this car is just silly. Why would I spend more money on AWD if that isn't what I wanted? I had the car built, bought exactly what I wanted and bought it for the exact reasons I've explained. I don't care if you think if every owner who tunes there BMW should put Mickey Thompsons on the car, doesn't matter to me. I know I won't be doing that and thus my decision makes sense for how I choose to drive and mod my car.

Once again, enjoy what you have and get on with your life.

[olaosunt]

Originally Posted by kdog26372

Also to Mustang guy, I don't care what others think and I've said numerous times enjoy what you have and each RWD and AWD has reasons to get and not get. Trying to say I've got some different agenda for why I chose AWD over RWD for this car is just silly. Why would I spend more money on AWD if that isn't what I wanted? I had the car built, bought exactly what I wanted and bought it for the exact reasons I've explained. I don't care if you think if every owner who tunes there BMW should put Mickey Thompsons on the car, doesn't matter to me. I know I won't be doing that and thus my decision makes sense for how I choose to drive and mod my car.

Once again, enjoy what you have and get on with your life.

Oh, I already do enjoy the mustang and the BMW.

I am proud to be a "mustang guy"... and a "BMW guy"....and an "Audi guy".

Sure beats a one dimensional "AWD BMW fanboy"

Believe me I plan to get on with my life and enjoy it the fullest even more once I am home from my deployment .

Fact is as YOU said you kept spinning when you had a tuned RWD BMW because you did not have the sense to invest in a set of sticky tires( and they don't have
to be drag radials)..... And then mindlessly parrot what you heard on here that RWD with snows are better than AWD with all seasons( I won't be surprised if you have all seasons on your X drive)
I don't really care what you chose to buy/and why with your own cash but quit trying to convince and mislead other people as to the reason .
You ask "WHY would you spend money on BMW with AWD if that is not what you wanted ?"... I am sure that is what you wanted because you could not drive a RWD one with a tune(without spinning)...that's why.��
Regarding the mustang forums - you do fit the bill of that stereotypical BMW owner I constantly try to convince them does not exist .
Enjoy your BMW ... And try to be safe O mighty stoplight warrior!

[Turbo_435i]

Originally Posted by olaosunt

Oh, I already do enjoy the mustang and the BMW.

I am proud to be a "mustang guy"... and a "BMW guy"....and an "Audi guy".

Sure beats a one dimensional "AWD BMW fanboy"

Believe me I plan to get on with my life and enjoy it the fullest even more once I am home from my deployment .

Fact is as YOU said you kept spinning when you had a tuned RWD BMW because you did not have the sense to invest in a set of sticky tires( and they don't have
to be drag radials)..... And then mindlessly parrot what you heard on here that RWD with snows are better than AWD with all seasons( I won't be surprised if you have all seasons on your X drive)
I don't really care what you chose to buy/and why with your own cash but quit trying to convince and mislead other people as to the reason .
You ask "WHY would you spend money on BMW with AWD if that is not what you wanted ?"... I am sure that is what you wanted because you could not drive a RWD one with a tune(without spinning)...that's why.��
Regarding the mustang forums - you do fit the bill of that stereotypical BMW owner I constantly try to convince them does not exist .
Enjoy your BMW ... And try to be safe O mighty stoplight warrior!

hey , im the stoplight warrior , not him

[Turbo_435i]

I've seen multiple videos online where the M235i xdrive does 0-60 in 4 seconds (+/-) a tenth second.

show me a video of a M235i rwd doing 0-60 same time and ill be convinced.

[kdog26372]

Originally Posted by olaosunt

Oh, I already do enjoy the mustang and the BMW.

I am proud to be a "mustang guy"... and a "BMW guy"....and an "Audi guy".

Sure beats a one dimensional "AWD BMW fanboy"

Believe me I plan to get on with my life and enjoy it the fullest even more once I am home from my deployment .

Fact is as YOU said you kept spinning when you had a tuned RWD BMW because you did not have the sense to invest in a set of sticky tires( and they don't have
to be drag radials)..... And then mindlessly parrot what you heard on here that RWD with snows are better than AWD with all seasons( I won't be surprised if you have all seasons on your X drive)
I don't really care what you chose to buy/and why with your own cash but quit trying to convince and mislead other people as to the reason .
You ask "WHY would you spend money on BMW with AWD if that is not what you wanted ?"... I am sure that is what you wanted because you could not drive a RWD one with a tune(without spinning)...that's why.��
Regarding the mustang forums - you do fit the bill of that stereotypical BMW owner I constantly try to convince them does not exist .
Enjoy your BMW ... And try to be safe O mighty stoplight warrior!

Yep, you've got me all figured out. I'm a huge fanboy and you are the best driver ever and have convinced me how stupid I was in my choice of car and setup. Thank God you've enlightened me, and no I've got summer tires for summer and winters left over from my 135i that will be put on for winter. Hopefully that is ok with you, I'm sure you've got a better setup for that as well. I don't know what post you keep saying I "parroted" anything about RWD with snows being better than AWD with all seasons. Where is this post??? I think you are mixing me in with another poster. Ok to rip into my posts, but I'd like them to actually be posts I've made.

And finally once again I'm not convincing anyone anything. I'm stating facts of why I do what I do with my cars. People can chose to use that info or get all bent out of shape like yourself because you have a different opinion and do different things. Good for you for having 3 different cars, I've had Mustangs, VW's, BMW's, Honda's, various pick up trucks, so what? You posted a big picture of a mustang with a time slip on a BMW forum, that's why I called you mustang guy. It's not meant to be derogatory, it's simply matches your post.

I gotta say I've been on these forums for 4 years and this is the only time someone's ever gotten all worked up over my posts. I've sold and bought items from other members, I've given my opinions and listened and debated with others. Are you having a bad week or something? This isn't a Fox News vs MSNBC forum, or is it?

[335BOY]

Originally Posted by olaosunt

Yes, that guy would be me

I don't want to think this is a "BMW thing" but I find it amusing that you think it odd for one to drive around on drag radials.

Of course you have to be sensible and on days when it rains I drive my Audi S4.I have a set of blizzaks for winter time on all my cars(except the mustang).

My Mustang makes 800 rwhp, runs the 1/4 in 10.3@138 through a manual, and can be safely driven on the street

with drag radias.







It has SLICKS on in the photo,nd NO I don't drive around on those as it

is not legal(although I know some people who do).


My point is, you chose a tire to match the purpose of your car,driving

style, weather condition and of course amount of rwhp and torque you make.

What is the point of moding and adding power if it all goes up in tire

smoke?..... bragging rights ?... or only all wheel drive cars should add

power because you cant drive around on drag radials(or whatever sticky tire

you choose).

YOU obviously wasted your money and time adding power to your RWD car if

all YOU did was spin the tires.May be YOU should have invested in drag

radials(and they cost less than AWD).

I am no red light warrior nor am I a road course hero( and I don't pretend to

be and have never been to one), but my M235 saw the drag strip regularly as I made sequential

changes to the bolt on's,tune,gas and finally tire(last change) in my quest

for an 11 second time slip.

If you want to truly test how fast your car accelerates, and not endanger any

one else(but yourself) in the process, the drag strip is the ONLY place to do

it.

I am certain even if you put drag radials on all 4 wheels of the X drive it is

not going to get a better a 60 ft. than 1.6, and by the 330 ft mark

the RWD drive car(with sticky tires) has already closed the gap AND will be

quicker to 60 mph(as it seems that is what many care about)..........



And lastly this fallacy that keeps getting

propagated (you parroted it here) about RWD with snows being better than AWD with all season. Absolute

nonsense.

I compared my Audi S4 with all seasons(I put snows on eventually) to the BMW with Blizzaks last winter and it was
no contest.
Like I said, before I suspect that is the main reason you switched to X drive, and not some" performance" reason like

you want others to believe.

What is more important stopping and turning or accelerating? RWD with 4 winter tires will be a MUCH safer car (stopping and turning)than AWD on all seasons. Its been proven hundreds of times. Its logic.

[Turbo_435i]

acceleration is more important.....
for me.

[Cyberdemon]

Originally Posted by schybrid

show me a video of a M235i rwd doing 0-60 same time and ill be convinced.

No one is trying to convince you anymore. Get the AWD car.