[moldcad]

Originally Posted by schybrid

Ive made up my mind.. Im getting the xdrive, and it will be better all the time vs rwd

Good for you! Good luck with your AWD, and may the power be with you

Just as it is with my RWD+LSD M235i and AWD Golf R

[Zooks527]

Originally Posted by pikcachu

btw the eDiff (electronica LSD) only comes on with DTC fully OFF and Sport mode != DTC OFF

I don't believe that's correct. At a minimum, xDrive uses the brakes to create the eDiff function in normal driving and the first stage of reduced traction control ('DTC' mode), albeit allowing more wheelspin in DTC mode before it pulls back the throttle. It also uses the steering wheel position to allocate torque side to side

It may also do so in full 'DSC off' mode, but without the steeling wheel position input, allowing the car to rotate around its axis without trying to correct it. I believe it still tries to match wheel spin rates.

[kdog26372]

Originally Posted by pikcachu

btw the eDiff (electronica LSD) only comes on with DTC fully OFF and Sport mode != DTC OFF

Well whatever it is, traction control, ediff, my tuned 135i sucked making 90 degree turns, car would pause and not really get moving until almost straight again. I added LSD and that helped tremendously with that aspect of the car, but did little to nothing for accelerating from a stop. The car could not handle the extra power of the tune and first gear was almost useless with second not much better. If I wanted to do burnouts I would have bought a mustang or camaro.

[olaosunt]

Originally Posted by kdog26372

Come on, this is guy isn't going to drive around town with drag slicks on and neither do you. He wants an M235i and wants to know which is quicker 0-60. Pretty simple, the xdrive will be with stock tires and if tuned even more so as it will put the power to the ground.

.

I am glad the OP has made up his mind but I just had to address the "this guy" comment.

Yes,I drive around on drag radials(NOT slicks) on all my cars without a problem ALL of the time except for Winter and why not?

The Mickey Thompson ET street II, is a DOT approved tire and actually rides better than the stock tires as it has more side wall being a 45 profile-and looks better.

They may not corner as well but they are fine for street driving.
The only reason I just bought a spare set of rear wheels to mount them on is to save the thread for the drag strip.

The fact is, a RWD M235 with sticky tires is fast as the AWD (if not faster) to 0-60,1/8 and 1/4 mile and will trap higher due to being lighter... and I have the time slip to prove it.

[/IMG]

I see you leave in Chicago so I suspect the weather is a bigger motivation for your AWD than you are letting on.

First thing I am going to do if I ever move out of the Midwest to where it does not snow is ditch the AWD drive cars I have now.

[pikcachu]

Originally Posted by Zooks527

I don't believe that's correct. At a minimum, xDrive uses the brakes to create the eDiff function in normal driving and the first stage of reduced traction control ('DTC' mode), albeit allowing more wheelspin in DTC mode before it pulls back the throttle. It also uses the steering wheel position to allocate torque side to side

It may also do so in full 'DSC off' mode, but without the steeling wheel position input, allowing the car to rotate around its axis without trying to correct it. I believe it still tries to match wheel spin rates.

well I was actually talking about the RWD version.... but still the xdrive doesn't apply the brakes...what applies the brakes is the DSC/DTC program... and the purpose is to keep stability... while the eDiff on DSC OFF mode is to optimize traction on turns....

the eDiff program is only active on DSC OFF... it's just sometimes it gets confused with the DSC/DTC as they both brake wheels individually but eDiff won't cut any power and eDiff won't do anything to the front wheels while DSC/DTC will brake any wheel it needs to

Also xDrive can't adjust torque side to side (like left wheel different from right wheel) it can only adjust torque front to back...at least last time i checked...

[Kayevman]

Originally Posted by raisingAnarchy

xDrive does not allow sport suspension or stickshift. RWD gives better fuel economy. Your profile says you live in the south so I think it's safe to say you won't need AWD.

Edit: just saw you say you want xDrive for performance reasons. I don't see how you're going to shred your tires in RWD without a really aggressive tune. And if you're leasing, then I'm not sure how you're going to tune it so aggressively and not have to pay extra at lease end.

What? My 2015 M235 I XDrive has the same suspension settings as the RWD. Fast, always goes where you point it. More fun in the rain when most everyone else has to creep along. I live in Texas. You can't always predict what conditions the road will challenge you with and you can't react as quickly as the car can. The character of a BMW doesn't have to be defined by how the rear can slide out of control. The X Drive feels like it has claws and it's fun to drive. I'm comparing my 235 to the 2005 E 46 I bought new and the 2102 135 I CV I had more recently. It's easier to drive fast. (FYI the tread seems to be longer lasting than
the RWD.)

[Zooks527]

Originally Posted by pikcachu

well I was actually talking about the RWD version.... but still the xdrive doesn't apply the brakes...what applies the brakes is the DSC/DTC program... and the purpose is to keep stability... while the eDiff on DSC OFF mode is to optimize traction on turns....

Nope, that's how the xDrive system works side-to-side. It varies brake load on all 4 wheels to maintain traction across the open differentials. It does have a hard clutch system at the transfer case, though, with a straight mechanical transfer to front or back that doesn't involve the brakes. Can't speak to RWD, but xDrive certainly does use the brakes at all times for a slipping wheel.

Originally Posted by pikcachu

Also xDrive can't adjust torque side to side (like left wheel different from right wheel) it can only adjust torque front to back...at least last time i checked...

Nope, xDrive has had side to side torque distribution since at least 2009. I'm looking for the old explicit video of the effect, but this one mentions right at the end that it will work if only 1 wheel has traction:

EDIT
And the last 2 seconds of this one show side-to-side torque vectoring. Still looking for the old one showing it running through curves on ice with torque spread.

[Turbo_435i]

Originally Posted by olaosunt

I am glad the OP has made up his mind but I just had to address the "this guy" comment.

Yes,I drive around on drag radials(NOT slicks) on all my cars without a problem ALL of the time except for Winter and why not?

The Mickey Thompson ET street II, is a DOT approved tire and actually rides better than the stock tires as it has more side wall being a 45 profile-and looks better.

They may not corner as well but they are fine for street driving.
The only reason I just bought a spare set of rear wheels to mount them on is to save the thread for the drag strip.

The fact is, a RWD M235 with sticky tires is fast as the AWD (if not faster) to 0-60,1/8 and 1/4 mile and will trap higher due to being lighter... and I have the time slip to prove it.

[/IMG]

I see you leave in Chicago so I suspect the weather is a bigger motivation for your AWD than you are letting on.

First thing I am going to do if I ever move out of the Midwest to where it does not snow is ditch the AWD drive cars I have now.

You failed to mention you were running E35 at the time of your 11.9 @ 114mph run ......

[pikcachu]

Originally Posted by Zooks527

Nope, that's how the xDrive system works side-to-side. It varies brake load on all 4 wheels to maintain traction across the open differentials. It does have a hard clutch system at the transfer case, though, with a straight mechanical transfer to front or back that doesn't involve the brakes. Can't speak to RWD, but xDrive certainly does use the brakes at all times for a slipping wheel.




Nope, xDrive has had side to side torque distribution since at least 2009. I'm looking for the old explicit video of the effect, but this one mentions right at the end that it will work if only 1 wheel has traction:

EDIT
And the last 2 seconds of this one show side-to-side torque vectoring. Still looking for the old one showing it running through curves on ice with torque spread.

Torque vectoring is only for the X6, X6M X5M with DPC (dynamic performance control) so won't be there for the regular 2 3 or 5 series..
Also I don't think you have torque vectoring for the front so you can't really do side-to-side there either in any case....

regular xdrive can't vary torque side to side

It's not the xDrive that varies the break load, xdrive has nothing to do with brakes (if you had no brakes...xdrive would work exaclty the same)... it's the DSC that controls braking of individual wheels... put the DSC OFF and the car won't apply any brakes (apart from the rear from eDiff program)... it will just vary torque front to rear

[Zooks527]

Originally Posted by pikcachu

I don't think you have torque vectoring for the front so you can't really do side-to-side there.... Also torque vectoring is only for the X6, X6M X5M with DPC (dynamic performance control) so won't be there for the regular 2 3 or 5 series..

regular xdrive can't vary torque side to side

Still looking for the videos that were available when I got my 2009. They were pretty clear about it.

EDIT: The last 5 seconds of this video is showing variable torque on all 4, albeit without narration on a 5 series touring.

[pikcachu]

Originally Posted by Zooks527

Still looking for the videos that were available when I got my 2009. They were pretty clear about it.

I'd love to see one

[Zooks527]

Originally Posted by pikcachu

Torque vectoring is only for the X6, X6M X5M with DPC (dynamic performance control) so won't be there for the regular 2 3 or 5 series..
Also I don't think you have torque vectoring for the front so you can't really do side-to-side there either in any case....

regular xdrive can't vary torque side to side

Actually, I think we're talking past each other on this point.

"Torque vectoring" as used in the X6 is a hard system using an active clutch in the rear axle, positively adding power to a wheel.

Torque shifting side to side in other iterations of xDrive is done using the brakes and an open differential, functionally the eDiff operation, and is typical across most non-clutch AWD systems.

Can't find the video, but did find the press release (note: hitting the link will download a Word document press release to your computer, not open a browser window).
https://www.google.com/url?sa=t&rct=...92291466,d.cWc

Page 14, describing xDrive as implemented in a 3-series:
"This interaction with DSC also provides a transverse lock function, forced distribution of power to the two front and, respectively, rear wheels by means of electronic intervention in the brakes: As soon as a wheel starts to spin without transmitting power, the brakes are applied specifically on that wheel, the differential in the final drive automatically feeding more power to the opposite wheel still maintaining its grip."

This is pretty much what I said back in posts #46 and #51, and it certainly supports the proposition that non-DPC xDrive can vary power side to side.

Originally Posted by pikcachu

It's not the xDrive that varies the break load, xdrive has nothing to do with brakes (if you had no brakes...xdrive would work exaclty the same).

No. See bold section immediately above. The xDrive transfer case would work exactly the same without brakes, but the overall xDrive system would not.



Yes, it's tied to the DSC and the DSC function itself can be turned off, however (page 9):
"Like on every BMW, DSC Dynamic Stability Control may also be deactivated on the all-wheel-drive models, enabling the sports-minded driver to enjoy all the dynamic driving qualities of his BMW in a controlled power slide by deliberately oversteering the car. The xDrive all-wheel-drive system as such cannot be deactivated."

Which, again, is what I said in post #46 above.

[kdog26372]

Originally Posted by schybrid

You failed to mention you were running E35 at the time of your 11.9 @ 114mph run ......

Exactly, you were on map 7 with higher octane and boost, other awd guy was 93 octane map 2, yet you were slower to 60' and only equal by the 330 ft time. If awd car put your slicks on, added higher octane and went map 7, pretty much guarantee you wouldn't be even by 330ft. The rwd advantage takes over by back 1/2 of 1/4 as shown in higher traps. Enjoy your ride and nice timeslip.

[pikcachu]

Originally Posted by Zooks527

Actually, I think we're talking past each other on this point.

"Torque vectoring" as used in the X6 is a hard system using an active clutch in the rear axle, positively adding power to a wheel.

Torque shifting side to side in other iterations of xDrive is done using the brakes and an open differential, functionally the eDiff operation, and is typical across most non-clutch AWD systems.

Can't find the video, but did find the press release (note: hitting the link will download a Word document press release to your computer, not open a browser window).
https://www.google.com/url?sa=t&rct=...92291466,d.cWc

Page 14, describing xDrive as implemented in a 3-series:
"This interaction with DSC also provides a transverse lock function, forced distribution of power to the two front and, respectively, rear wheels by means of electronic intervention in the brakes: As soon as a wheel starts to spin without transmitting power, the brakes are applied specifically on that wheel, the differential in the final drive automatically feeding more power to the opposite wheel still maintaining its grip."

This is pretty much what I said back in posts #46 and #51, and it certainly supports the propsition that non-DPC xDrive can vary power side to side.




No. See bold section immediately above. The xDrive transfer case would work exactly the same without brakes, but the overall xDrive system would not.



Yes, it's tied to the DSC and the DSC function itself can be turned off, however (page 9):
"Like on every BMW, DSC Dynamic Stability Control may also be deactivated on the all-wheel-drive models, enabling the sports-minded driver to enjoy all the dynamic driving qualities of his BMW in a controlled power slide by deliberately oversteering the car. The xDrive all-wheel-drive system as such cannot be deactivated."

Still xdrive can't vary the torque side to side... you are just braking one wheel and the brakes are eating all the torque...

Say torque distribution front to rear at a given time is 40F - 60R
So basically at the rear you have 30% torque to each wheel, now one wheel start spinning, what it will do (like ediff when dsc is off) is brake one wheel but the most one wheel will ever get is 30% while the other one will get 2 or 3% in a hope it gets traction...and the brakes is eating the other 27% torque

It's not like you can send 57% out of the 60% available for the rear, to one wheel and 3% to the other.... it just sends 30% each, and you get 30% and 3%, wasting 27% through the brake pads

If that's what you mean with vary torque side to side then you are right..... but it's really not varying anything... it's sending the same torque all the time to each wheel and then wasting the torque with the brakes

You could use 2 LSD's (one front, one rear) if you wanted side to side torque distribution....like the subaru symetrical awd for example...

[moldcad]

xDrive in 2-series has no torque-vectoring, period. Some help in moving the car forward when wheel spin(s) comes from e-Diff, but the real thing - the mechanical closed differential - is only available for RWD. That's why I said that unless you live in a heavy snow area, RWD plus M-P LSD is the best way to go.

I'm talking from experience - did have a 5-series xDrive, do have M235i with LSD. Only the latter is a true bimmer by my books...

[Zooks527]

Originally Posted by pikcachu

Still xdrive can't vary the torque side to side... you are just braking one wheel and the brakes are eating all the torque...

Say torque distribution front to rear at a given time is 40F - 60R
So basically at the rear you have 30% torque to each wheel, now one wheel start spinning, what it will do (like ediff when dsc is off) is brake one wheel but the most one wheel will ever get is 30% while the other one will get 2 or 3% in a hope it gets traction...and the brakes is eating the other 27% torque

It's not like you can send 57% out of the 60% available for the rear, to one wheel and 3% to the other.... it just sends 30% each, and you get 30% and 3%, wasting 27% through the brake pads

If that's what you mean with vary torque side to side then you are right..... but it's really not varying anything... it's sending the same torque all the time to each wheel and then wasting the torque with the brakes.

OK, let's look at this using just your description.

At the start, you have 30% of engine torque going to the road on the left, 30% to the road on the right, before a wheel starts to spin.

Then, a wheel starts to spin. As it's an open differential, you now get 3% to the road on the left, 3% to the road on the right, 54% to rotational momentum of the right wheel.

The braking function kicks in. You now have 30% of engine torque going to the road on the left, 3% to the road on the right, and 27% to heating the right brake pads.

So, at the end case of your example, you have 10x as much torque being applied to the road on the left side of the car than on the right. You've moved 27% of the engine's torque from rotational momentum of the right wheel to force applied to the road at the left wheel. But you would like to quibble about the definition of "vary" in your force diagram.

I'll go back to my last comment about talking past each other. Your point is that the car can't create more total torque on one side of the car than on the other. That's true. My point, that xDrive can vary side-to-side where the torque is applied to the road, is also true.

Originally Posted by moldcad

but the real thing - the mechanical closed differential - is only available for RWD.

I can't speak to Europe, but this is not true in the United States. The mechanical LSD is available for the M235xi here.

[pikcachu]

Originally Posted by Zooks527

you have 10x as much torque being applied to the road on the left side of the car than on the right. But you would like to quibble about the definition of "vary" in your force diagram.

I'll go back to my last comment about talking past each other. Your point is that the car can't create more total torque on one side of the car than on the other. That's true. My point, that xDrive can vary side-to-side where the torque is applied to the road, is also true.

you have 10x as much torque but you could have much more too.... Don't get me wrong... it's better than nothing but it's not the optimal...

It's not that I like to quibble.... the wheels, from the drivetrain get exactly the same amount of torque....it's just that by wasting torque through the help of the brakes you get the impression that xdrive can "vary" torque side-to-side...

I don't think you can put an LSD on an M235xi either... would love to see any link showing otherwise

[Zooks527]

Originally Posted by pikcachu

It's not that I like to quibble.... the wheels, from the drivetrain get exactly the same amount of torque....it's just that by wasting torque through the help of the brakes you get the impression that xdrive can "vary" torque side-to-side...

You know, not to be a PITA, but when you have something that, in your example, lets you put down any selectable value for a specific wheel from 3% to 30% of engine torque to the road (which is the only place where it counts), it's tough to describe that as anything other than "variable".

Yes, that selectable value can't exceed 50% of the torque going to that wheel's axle. It can still vary from side to side on that axle, subject to the 50% limit. Now, had I said "increase" ....

Originally Posted by pikcachu

I don't think you can put an LSD on an M235xi either... would love to see any link showing otherwise

http://www.shopbmwusa.com/PERFORMANC.../DIFFERENTIALS

Realoem also shows option for either the standard or MPerf LSD for the rear end:
http://www.realoem.com/bmw/showparts...31&hg=33&fg=05

Both cars (M235i and M235xi) use the same part number for the normal differential, so there shouldn't be any valid reason why the LSD won't fit.

[pikcachu]

Originally Posted by Zooks527

You know, not to be a PITA, but when you have something that, in your example, lets you put down any selectable value for a specific wheel from 3% to 30% of engine torque to the road (which is the only place where it counts), it's tough to describe that as anything other than "variable".

Yes, that selectable value can't exceed 50% of the torque going to that wheel's axle. It can still vary from side to side on that axle, subject to the 50% limit. Now, had I said "increase" ....

http://www.shopbmwusa.com/PERFORMANC.../DIFFERENTIALS

Realoem also shows option for either the standard or MPerf LSD for the rear end:
http://www.realoem.com/bmw/showparts...31&hg=33&fg=05

Both cars (M235i and M235xi) use the same part number for the normal differential, so there shouldn't be any valid reason why the LSD won't fit.

It's not the drivetrain varying the torque. It's the brakes. With your thinking any car that can brake wheels individually can vary torque side to side then.

One thing is the be able to send different amount of toque to each will individually and another is sending the same amount and apply the brakes to reduce torque on some wheel

I'm done with this, if you don't want to understand it, It's up to you. Won't waste more time trying to explain it.

[Zooks527]

Originally Posted by pikcachu

It's not the drivetrain varying the torque. It's the brakes. With your thinking any car that can brake wheels individually can vary torque side to side then.

One thing is the be able to send different amount of toque to each will individually and another is sending the same amount and apply the brakes to reduce torque on some wheel

I'm done with this, if you don't want to understand it, It's up to you. Won't waste more time trying to explain it.

As I said, "talking past". If you'd read my responses, you'd see I do understand what you've been saying. You seem to be unable to understand that "sent to the wheel" is irrelevant. "Sent to the ground" is what counts.

But, look at the bright side. After insisting it didn't, you learned that the xDrive system does use the brakes. Think of it as a positive takeaway.

[pikcachu]

Originally Posted by Zooks527

As I said, "talking past". If you'd read my responses, you'd see I do understand what you've been saying. You seem to be unable to understand that "sent to the wheel" is irrelevant. "Sent to the ground" is what counts.

But, look at the bright side. After insisting it didn't, you learned that the xDrive system does use the brakes. Think of it as a positive takeaway.

Yes... and xdrive using the brakes to give you the illusion it "varies" torque, doesn't send as much torque to the wheel as it could if it would properly vary torque to each wheel individually...

If xdrive could vary torque side to side why wouldn't BMW advertise it? You can't find any videos or info anywhere for a reason

in the same way an eDiff is not even close to a mechanical LSD

Yes i guess you always learn something new....

Can you show us any xDrive vehicle that has M perf LSD on? i didn't know that was posible...

[Zooks527]

Originally Posted by pikcachu

Yes... and xdrive using the brakes to give you the illusion it "varies" torque, doesn't send as much torque to the wheel as it could if it would properly vary torque to each wheel individually...

You know, for someone who's "done with this", you're being a bit verbose. However,...

You seem to be unable to understand the word "vary". In your example in post #58 above, you posit a case where the wheel on the opposite side of a wheel that is spinning is putting 3% of engine torque down to the ground, and is then putting 30% of engine torque down to the ground after application of the brakes to the spinning wheel. If 3% going to 30% doesn't count as "varying", I don't think we're using the same definition of the word.

Sure, you can't get more down to the ground than is being sent to the other half of the axle. So what? That doesn't effect the fact that the torque applied to the ground through the non-spinning wheel can be varied from the amount being applied by the spinning wheel to 10x that amount.

It's coming back to the fact that you're fixated on torque being sent to the wheel, as opposed to torque being sent to the ground. Sure, the amount sent out each half of the axle is the same. What counts is that the useable amount applied to the ground can be varied so that each side is different.

Originally Posted by pikcachu

If xdrive could vary torque side to side why wouldn't BMW advertise it? You can't find any videos or info anywhere for a reason

No, absence of proof is not proof of absence.

Would you like me to speculate? Sure. If they advertised it since the DPC system came out, it would cut into their marketing effort to shill that. Is that the case? Beats the hell out of me. Ask them.

EDIT: Whoops, there it is, on the main BMW site (as opposed to BMWUSA). Go here: http://www.bmw.com/com/en/insights/t...echnology.html

Select the "How BMW xDrive Works" video. Watch it from 0:12 to 0:17. Notice the wheel torque graphic arrows. They'll be swinging side-to-side as the animation progresses. See below for two images cut from it.

Originally Posted by pikcachu

in the same way an eDiff is not even close to a mechanical LSD

And a pig isn't close to an eagle. Again, so what? Where did I ever imply, let alone try to make the case, that an eDiff is close to a mechanical LSD?

Originally Posted by pikcachu

Yes i guess you always learn something new....

Perhaps you might want to dial the smug down just a bit. After all, in your post #53 above, you were clearly unaware that xDrive uses the brakes as part of its control system ("It's not the xDrive that varies the break load, xdrive has nothing to do with brakes (if you had no brakes...xdrive would work exaclty the same).."). I will confess that that particular omission did make me a bit less inclined to accept your technical analysis of the system.

After all, if one wishes to opine on how the system works, shouldn't one, you know, know how the system works?

Originally Posted by pikcachu

Can you show us any xDrive vehicle that has M perf LSD on? i didn't know that was posible...

Hell, I can't show you a red one, as I haven't seen one to date. So what? BMW says they make them in red and I believe it.

Regarding the LSD, I did give you a link to BMW USA's website, showing that it's available. I also gave you a link to a parts site that gave you the part number for it. If you don't believe two external sources, one of which is the manufacturer's website, I can't do anything about it.

Now, I'll accept that you didn't know it was possible. But all that proves is that there's a number of things that you don't know about xDrive cars.