[MFactory]

Traction control DOES NOT transfer any torque between left/right wheels. An ecu program cannot do this, as the only thing that physically transfer torque is the Differential. An ecu program can "control" this, but only if you have an LSD that accepts electronic input.

An Open Diff does not accept electronic input/control. All your Traction Control is doing is applying brake to slow down the spinning wheel, end of story.

[MFactory]

Originally Posted by Dozhdbog

I wish you'd just read that other thread I posted. Your questions are answered fully there. This EXACT issue you're having is gone over very well. I promise that thread is a good read, especially the coding bits at the end.

Suffice it to say that the application of torque and the friction losses are essentially identical.

I don't have an issue, as I know how a Differential works, and I know how an ecu program works.

One serves to control, one serves to function. Guess which is which? Function is determined (and limited) by it's "mechanical" design, regardless of how much control you have.

Again, I don't want to take this off topic more than what it already has, so I will refrain from posting further.

To the OP: If you want to learn more about how a differential works, I suggest reading other resources as well (Google is your friend), and not just relying on forum posts

[Dozhdbog]

So, to conclude:

Open diff sucks.

E-Diff on an open differential BMW is identical to an m-diff (a mechanical LSD) in friction loss and power transfer, but can come on and off a bit suddenly under extreme conditions and causes the brakes to heat and wear more quickly.

M-Diff (mechanical LSD) is preferred for serious racing.


Now, the original poster needs to decide if his car requires an m-diff or not, since I do believe it already has BMW's ADB e-diff system.

[Dozhdbog]

Originally Posted by MFactory

Traction control DOES NOT transfer any torque between left/right wheels. An ecu program cannot do this, as the only thing that physically transfer torque is the Differential. An ecu program can "control" this, but only if you have an LSD that accepts electronic input.

An Open Diff does not accept electronic input/control. All your Traction Control is doing is applying brake to slow down the spinning wheel, end of story.

I am talking specifically about BMWs electronic differential system, called ADB (Automatic Differential Brake). Not about DTC (Dynamic Traction Control) or DSC (Dynamic Stability Control). They are discrete systems that can work with each other or not depending on the push of a button or coding.

You keep mixing up terminology here.

An ECU DOES control the electronic differential system and it does so very well. As stated previously, in application, it works nearly identically to a mechanical differential. The electronic differential in certain BMW's (which I believe includes the OP's) transfers power just like a mechanical LSD does, but does so via application of the brakes.

[MFactory]

Originally Posted by Dozhdbog

So, to conclude:

Open diff sucks.

E-Diff on an open differential BMW is identical to an m-diff (a mechanical LSD) in friction loss and power transfer, but can come on and off a bit suddenly under extreme conditions and causes the brakes to heat and wear more quickly.

M-Diff (mechanical LSD) is preferred for serious racing.


Now, the original poster needs to decide if his car requires an m-diff or not, since I do believe it already has BMW's ADB e-diff system.

Originally Posted by Dozhdbog

I am talking specifically about BMWs electronic differential system, called ADB (Automatic Differential Brake). Not about DTC (Dynamic Traction Control) or DSC (Dynamic Stability Control). They are discrete systems that can work with each other or not depending on the push of a button or coding.

You keep mixing up terminology here.

An ECU DOES control the electronic differential system and it does so very well. As stated previously, in application, it works nearly identically to a mechanical differential. The electronic differential in certain BMW's (which I believe includes the OP's) transfers power just like a mechanical LSD does, but does so via application of the brakes.

[Dozhdbog]

I feel we're getting somewhere, finally.

[magicbmw]

Now I know this car has DTC, but don't know if it has the e-diff, but past experiences w/open diff's are that if u turn corner romp throttle the rear is not predictable because weight transfers from l-r-l so on making high power very tough to manage ( throw in wet road then unmanagable), where as LSD the rear of car is predictable even in weather/power.

The LSD is gunna deliver what you throw at it, where as (the DTC/or e-diff) would computer adapt to road, correct?

If max FUN & power (lighting them up on command) is what is the goal then the LSD is choice, but if you can have the e-diff control also (be able to turn off/on at will) that could be very beneficial also.

So how do figure out if it has e-diff?

[MFactory]

Originally Posted by Dozhdbog

I feel we're getting somewhere, finally.

You still have a lot to learn. May the force be with you, my young padawan

[Dozhdbog]

Originally Posted by MFactory

You still have a lot to learn. May the force be with you, my young padawan

And with you as well.

[MFactory]

Originally Posted by magicbmw

Now I know this car has DTC, but don't know if it has the e-diff, but past experiences w/open diff's are that if u turn corner romp throttle the rear is not predictable because weight transfers from l-r-l so on making high power very tough to manage ( throw in wet road then unmanagable), where as LSD the rear of car is predictable even in weather/power.

The LSD is gunna deliver what you throw at it, where as (the DTC/or e-diff) would computer adapt to road, correct?

If max FUN & power (lighting them up on command) is what is the goal then the LSD is choice, but if you can have the e-diff control also (be able to turn off/on at will) that could be very beneficial also.

So how do figure out if it has e-diff?

Your 335i/d will have the pseudo e-Diff (read: marketing. Hint: google Ferrari e-Diff to learn what a real e-Diff is)

Is it beneficial? yes. Will you have more fun with a real LSD? yes

Am I wrong with that statement? No, but some think I am, so that's why I offer a 30day money back guarantee on our LSD's

[Dozhdbog]

Originally Posted by magicbmw

Now I know this car has DTC, but don't know if it has the e-diff, but past experiences w/open diff's are that if u turn corner romp throttle the rear is not predictable because weight transfers from l-r-l so on making high power very tough to manage ( throw in wet road then unmanagable), where as LSD the rear of car is predictable even in weather/power.

The LSD is gunna deliver what you throw at it, where as (the DTC/or e-diff) would computer adapt to road, correct?

If max FUN & power (lighting them up on command) is what is the goal then the LSD is choice, but if you can have the e-diff control also (be able to turn off/on at will) that could be very beneficial also.

So how do figure out if it has e-diff?

If you plan on really throwing the car around (in a safe environment, responsibly, and I'd recommend only after taking a course with a professional if you haven't done so already), then you should have DTC and DSC turned off to take full advantage of the e-diff.

Both DTC and DSC can and do cut power and nanny the car around corners and during rapid weight transfers during extreme driving.

You should then see if you can drive a similar car equipped with a mechanical LSD. The differences are there under extreme maneuvers, but not as great as some would have you believe. It's more in the feel than the application, if you get my drift (pun intended).

It all comes down to the individual, but if you're tracking your car competitively, I definitely agree a mechanical LSD is for you (along with some other upgrades).

[SHEEDI]

Originally Posted by I'm wrong

Instead of "correcting" people and posting irrelevant "evidence", you could spend the time learning a bit. We're all here to learn.

You are WRONG man

[Dozhdbog]

BMW did an excellent job developing their electronic differential system, but to really get a feel for it, you need to turn the nannies off.

Again, I stress, do so only in a responsible manner in a safe environment.

[SHEEDI]

would LSD help RWD car with snow tires getting out of snow?

[Dozhdbog]

Originally Posted by SHEEDI

would LSD help RWD car with snow tires getting out of snow?

No. All hope is lost at that point. Abandon the car.

[MFactory]

You really should stop calling it an e-Diff, as it has nothing, nada, zilch, to do with a Differential. It is economically impossible for a sub-$50k car to have an electronic differential, as it costs millions to design and implement one. And everyone who owns an MT/DCT 135i/335i/335d are well aware of how much cost-cutting BMW done to their latest models

To put it simply, if you drive like a pu$$y and lift off the gas when you get scared, Traction Control (yes, Traction Control, not the fancy name Marketing Departments are spewing from their mouths these days) will suffice as you are dying to slow down anyway (pun intended)

If you have balls of steel and apply more gas (which Traction Control won't allow you to do), then a real LSD is where the fun is at

[MFactory]

Originally Posted by SHEEDI

would LSD help RWD car with snow tires getting out of snow?

Yes, as proven time and time again

[Dozhdbog]

Originally Posted by MFactory

You really should stop calling it an e-Diff, as it has nothing, nada, zilch, to do with a Differential. It is economically impossible for a sub-$50k car to have an electronic differential, as it costs millions to design and implement one. And everyone who owns an MT/DCT 135i/335i/335d are well aware of how much cost-cutting BMW done to their latest models

To put it simply, if you drive like a pu$$y and lift off the gas when you get scared, Traction Control (yes, Traction Control, not the fancy name Marketing Departments are spewing from their mouths these days) will suffice as you are dying to slow down anyway (pun intended)

If you have balls of steel and apply more gas (which Traction Control won't allow you to do), then a real LSD is where the fun is at

I call it an e-diff because that's the common catch-all term for the various automated differential braking systems used in most of the car forums I frequent. It's official name according to BMW is ADB, or Automatic Differential Brake system.
I am sure you understand how and why everyone calls it e-diff now, and complaining about it isn't going to change much. In fact, I prefer e-diff over automatic diff because it's more descriptive of what it actually is, an electronic differential system (mechanical LSDs are also automatic, as it were).

BMW's Dynamic Traction Control is a discrete system, as I already explained, from the e-diff, and can operate in conjunction or separate from the e-diff. The e-diff can only be turned off through coding or pulling a fuse/wire. DTC and DSC can be fully turned off via the dash button.


I agree with you that the latest 3 series is lacking, but that's my personal opinion. BMW made a strategic move to tone the sportiness down and increase the comfort, and apparently it worked since they're still selling like hotcakes.
However, the e9x is not the latest model, and the development of BMW's e-diff for the 3 series started on my and the op's platform. You can keep slamming BMW and their cars, but it's really a good system, and has been shown to act nearly identically to a mechanical LSD.

[hassmaschine]

actually what you're really missing in this argument, and I'm surprised Mfactory hasn't picked up on it - is how an LSD can affect the car's traction & stability under braking & cornering. I'm pretty sure that's not something an e-diff can simulate, as on a clutch based diff the ramp rates have a significant effect on how the car turns into a corner.

the e-diff is fine for a DD. it sucks on a track. Sure, you can probably get a few good laps out of it - until it starts to overheat your brakes, then the DME puts you into limp mode/reduced power so you don't crash the car. Fun.

[Dozhdbog]

Originally Posted by hassmaschine

actually what you're really missing in this argument, and I'm surprised Mfactory hasn't picked up on it - is how an LSD can affect the car's traction & stability under braking & cornering. I'm pretty sure that's not something an e-diff can simulate, as on a clutch based diff the ramp rates have a significant effect on how the car turns into a corner.

the e-diff is fine for a DD. it sucks on a track. Sure, you can probably get a few good laps out of it - until it starts to overheat your brakes, then the DME puts you into limp mode/reduced power so you don't crash the car. Fun.

Apparently, according to the the op in http://www.1addicts.com/forums/showthread.php?t=719012 it ramps nearly identically to a mechanical LSD. Friction is applied identically. Only in very extreme situations does it have sudden application and deapplication. I don't track competitively, but have done some days on closed courses and found it works admirably well as far as my skill level goes. But yeah, the overheating is an issue as is the brake wear/build up on the rotors (I know from experience).

[MFactory]

I was too busy trying to educate how an Open Diff functions and why it is impossible for a software program to change it's physical operation, but alas, I failed my young padawan.

And no, it doesn't matter what the marketing departments call it, it is still NOT an electronic differential (seriously, google Ferrari e-Diff to learn what a real electronic differential is); it is simply an over-hyped electronic braking system that has nothing to do with the differential. All it does is simply slow down the spinning wheel, which in turn reduces the torque. An LSD increases torque to the wheel with traction, not reduce it.

Marketing departments are having a field day, and consumers are sadly believing the hype...

[Dozhdbog]

Originally Posted by MFactory

I was too busy trying to educate how an Open Diff functions and why it is impossible for a software program to change it's physical operation, but alas, I failed my young padawan.

That wasn't the point I was making, but you did wish to keep talking about it with me for some reason. However, I want you to know I am totally with you on how open diffs function. We agree 100% on that.

And no, it doesn't matter what the marketing departments call it, it is still NOT an electronic differential (seriously, google Ferrari e-Diff to learn what a real electronic differential is); it is simply an over-hyped electronic braking system that has nothing to do with the differential. All it does is simply slow down the spinning wheel, which in turn slows down your car. An LSD makes you quicker, not slower.

It's called a differential because it transfers power between the wheels. It's called electronic because it's electronic. It doesn't slow your car down. Friction losses are identical to the friction losses in a mechanical diff. How do you think a mechanical diff shifts power? Why do mechanical diffs have cooling fins?

Mechanical limited slip differentials perform the exact same function (as electronic differentials), though instead of using the brakes to apply friction on the spinning wheel, mechanical friction is applied inside the differential.