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      07-22-2012, 10:18 AM   #89
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Quote:
Originally Posted by imported_mega View Post
what? I said they feel completely different

my biggest complaint about my 135 is the open diff
Oops. So busy arguing with people that laugh at me for making a point.

Got caught up in it. Sorry.
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      07-22-2012, 01:14 PM   #90
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Just for reference:
Since Autocross tracks change every time, one can't compare times before/after. But comparing my times against the "usual suspects" (other drivers that are usually running similar times), I would estimate LSD made about 0.5s-0.75s difference on a 60s lap.

Quote:
Originally Posted by imported_mega View Post
my biggest complaint about my 135 is the open diff
What's your complaint?
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      07-22-2012, 03:03 PM   #91
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Quote:
Originally Posted by imported_mega View Post
I dont see it making a difference on race track lap times, where the turns are not so sharp and are high speed
True, on a road course the tight turns where LSD fixes inside wheel spin are less important, and half of them are throwaways. But they're so much more fun with limited slip. In high speed corners, LSD improves stability over bumps and curbings and makes throttle steer much easier, especially power oversteer. I don't know about lap times, but for me it's a much more enjoyable driving experience that justifies the cost.
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      07-22-2012, 04:10 PM   #92
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Feel is very subjective. If someone spends several thousand dollars on a Mechanical LSD human nature dictates that he will feel a significant improvement. The question is, who are you racing against and what are the rules? Does a mod like a mechanical LSD put you in a different class? To me a lot of the mod scene is not about racing but more about acquiring things and modding for modding's sake alone. If it is enjoyable do it. That is the pursuit of happiness. Some of this arguing seems pointless.

In my view there is a lot of enjoyment to be had by seeing how one's own skills improve without changing the car.
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      07-25-2012, 11:30 AM   #93
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int2str, is all the datalogging you've shown so far include the use of the upgraded mechanical lsd? If so, might the graphs look different with the stock open diff?
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      07-26-2012, 09:07 PM   #94
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Quote:
Originally Posted by int2str View Post
Honestly, I find that quite shocking. Unless they were modern cars that like our BMWs have electronic aids in addition to the open differential.
I recently drove an older, open diff 528i again and the difference to even a stock 135i is shocking. I would find it hard to believe that the difference isn't obvious. With a completely open diff, the inside wheel lights up like a Christmas tree around pretty much every corner.
I've driven an early 335i with an open diff (newer 335i's have the e-LSD) and other BMW's with open diffs and my 135i with the e-LSD on the same track, and I can certainly confirm the e-LSD is not at all the same as the open diff. It is certainly better than an open diff if those are your only 2 options.
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      07-27-2012, 01:31 AM   #95
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On a tight track I've managed to leave two black wavy lines for 50 metres out of a corner so the eLSD seems to do something
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      07-28-2012, 11:55 AM   #96
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Having now driven both I can say the Mechanical LSD trumps the ELSD. That said, the ELSD trumps open diff for sure.

The Elsd feels so passive while the Mlsd feels active. The Mlsd lets you keep the tail out as long as you want. Also, the Mlsd seems to deliver power in the turns better then the Elsd. This is my first hand experience.
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      07-28-2012, 08:31 PM   #97
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Quote:
Originally Posted by mike the snake View Post
My 135 when I gun it hard in 1st and 2nd (everything off) lurches from side to side when it spins the wheels, it goes anything but straight, and I am sure this is due to the eLSD.
Between the turbo power hitting so hard and unpredictably, and the eLSD causing the car to swerve under hard excelleration, I have all but stopped driving hard until I get a real LSD.
It's even worse in the rain.

To me, the eLSD isn't a performance thing, it's for super slow, tight turns like going up tight switchbacks where the inside wheel spins, or for mud or snow (again, slow traction conditions) because for performance driving, to me, the eLSD seems almost dangerous.
I haven't experienced any of what you just stated.
On hard launch, my 135i launches powerfully and smoothly, and goes where I direct it to.
It doesn't launch arrow straight at times, but it's far from lurching left to right. Maybe something is wrong with your car?

Your power delivery is unpredictable? Other than the slow throttle response, the power coming from my engine is easily predictable with my throttle use.
I've never been surprised by getting power when I didn't ask for it.

I used to have a slightly modded Plymouth/Mits Laser/Eclipse turbo FWD.
Now, launching that car was literally a hand full. It has an open differential, and on hard launch the front would shoot and dart left to right, and you really needed to have a good grip on the steering wheel under full boost.

The way you describe your car it sounds downright dangerous as it's out of control swinging left to right and giving bursts of power that seem to come from nowhere. That does sound dangerous.
But, compared to my experience, that description isn't universal.
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      10-10-2012, 09:33 AM   #98
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Quote:
Originally Posted by int2str View Post
That's for another thread.
Attached is another graph for you. The bottom, blue lines show the differential braking of the inside wheel. Notice how little the brakes are applied (compare it to me actually braking for the next turn) and how gradual and steady the brakes are applied. You can see though that the wheel speed balance is somewhat upset though (center charts), but the explanation is not the diff - it's the driver. Look at my sloppy throttle input (top chart).
Thanks for this thread and all the info. Certainly gives me a bit more faith in my e-LSD. I would like to have a Wavetrac fitted but getting a hold of one in Aus or importing it is difficult. Nevertheless, this thread has given me a bit more info and therefore confidence to take to the track. I was also under the incorrect assumption that the inside wheels brake were pulsed, but you seemed to have curbed that thought.

Might I ask how you managed to obtain all that telemetry? I wouldn't mind that sort of info to take back home from the track and analyze how to improve myself out there.
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      10-10-2012, 06:00 PM   #99
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Thumbs up

Quote:
Originally Posted by kb135 View Post
Might I ask how you managed to obtain all that telemetry? I wouldn't mind that sort of info to take back home from the track and analyze how to improve myself out there.
Data was acquired using an AIM Solo DL:
http://m-world.us/aim_solo_dl_gps_la...ta_logger.html

It's a great unit! I also use it to overlay data onto videos:
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      07-29-2013, 08:45 PM   #100
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I once had all the nannies crap out on me, and the car was uncontrollable when attempting to drive it as I normally would. I had to granny it from a stop or it would just spin a wheel in place, take corners very carefully or it would spin out, and keep it below 65, otherwise a scary shimmy would develop.
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      07-30-2013, 01:56 AM   #101
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Quote:
Originally Posted by Bimmer-Bob
Any idea if the 128i has the e-diff or not? I've read some press releases that seem to imply that it is only included on the 135i (along with more sport-oriented traction control logic, maybe?), but I haven't come up with anything definitive.
I have 2010 328i Mt. I have a place nearby where I can lift one wheel off. I tried to DSC, DTC, everything off - one of the rear wheels spins and the car doesn't go anywhere.

So, my guess is, - either only x35s have them, or amount of braking is very moderate.

Also, I remember reading somewhere that ADB single wheel braking works on speeds under 25 either mph or km/h.

Last edited by accel; 03-12-2014 at 12:10 AM..
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      03-24-2014, 04:11 AM   #102
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Does the 1m and m3 have the E-diff?

Is it possible to code the e-diff away? If the 1m doesn't have it its should be possible, right?

I have the m3 diff mounted on my 135i and i want to do a burn out with out the brake system forces my rear wheel not to spin!
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      03-25-2014, 11:24 AM   #103
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I still like the old mech LSD, just my thing
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      11-14-2014, 12:22 PM   #104
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Quote:
Originally Posted by int2str View Post
Can I turn this system off?

No. Even with all traction and stability control (DTC and DSC) turned off, differential braking is still enabled.
I read that the eDiff is only activated when DSC is off? or is it on all the time?
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      11-16-2014, 09:00 PM   #105
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All the time.
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      11-17-2014, 07:04 AM   #106
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Elsd sucks big balls I just got rid of it wish I did it right away.
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      11-17-2014, 09:47 PM   #107
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Quote:
Originally Posted by Zombie1 View Post
Elsd sucks big balls I just got rid of it wish I did it right away.
Did you actually get code it out somehow or just install a mechanical LSD?
Even if you have a mechanical LSD the elsd is still there, it just doesn't have to intervene as much.
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      11-18-2014, 09:13 AM   #108
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Quote:
Originally Posted by Nugget View Post
Did you actually get code it out somehow or just install a mechanical LSD?
Even if you have a mechanical LSD the elsd is still there, it just doesn't have to intervene as much.
I have not found out how to code it out yet, but it hasnt kicked in once to my knowlegde even with the pouring rain we had in New York yesterday. Maybe there is a fuse to pull to shut it off?
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      12-15-2014, 12:29 PM   #109
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wheel speed

Quote:
Originally Posted by int2str View Post
I'd like to dis-spell some rumors and clear up some misconceptions regarding BMWs electronically controlled differential or as some call it the "electronic LSD".

The BMW 1-series as well as many other recent BMW models feature an electronically controlled Automatic Differential Brake (ADB) system, that in conjunction with a normal open rear differential works to emulate a traditional mechanical limited slip system.

Below are some questions I've compiled based on forum posts I've found here. Feel free to ask more questions and I'll update this FAQ periodically.

All these answers are from my personal experience and to the best of my knowledge. I reserve the right to make corrections as better information becomes available.

----

Does the 1-series (or other recent BMWs) have an open rear differential?

Mechanically, the answer is yes - there is a completely open rear differential between the two rear wheels. This open diff is however assisted by an automatic differential braking system that will apply resistance to one wheel to equalize traction between the two wheels.


What does that look like in action?

Here's a graph showing the on-board telemetry of a 135i during an autocross run going around a left hand corner:


The light blue line shows braking force applied to the left (inside) rear wheel and the yellow line shows braking force applied to the right (outside) rear wheel. Dark blue shows the throttle pedal position and the red line show the brake pedal.

As you can see, without any brake pedal applied, the car applies some light brake pressure to the inside (less loaded) rear wheel to prevent wheel spin.

Also note that when the brake pedal *is* actually pressed, the car still manages the left/right brake balance to keep the car as neutral as possible under braking.

This car was equipped with a mechanical LSD as well - so even with a mechanical LSD, the system still provides additional inputs.


If I loose traction, will only 1 wheel spin?

No. The system automatically applies brake pressure to the wheel with the least amount of traction to get both wheels spinning.


Does the system reduce engine power?

No. Brake pressure is applied to one wheel, the engine power is not affected.


Will the braking force lock up the wheel or slow me down?

No. Only light brake pressure is applied to the spinning wheel this does not slow the car down. Mechanical limited slip differentials perform the exact same function, though instead of using the brakes to apply friction on the spinning wheel, mechanical friction is applied inside the differential.


Does this system interfere even if I'm not smoking tires?

Yes. The electronic differential braking acts even if you're not lighting up tires to help stabilize the car in a variety of situations.


Can I turn this system off?

No. Even with all traction and stability control (DTC and DSC) turned off, differential braking is still enabled.


Can I drift with the only the electronic differential?

Yes, absolutely!


Do I still need a mechanical LSD then?

Maybe. This is a tough question to answer and a personal one at that.

The electronically assisted differential works rather well actually. It puts power down to both wheels, allows drifting and generally provides a positive driving feedback and control.

However, the electronic system has it's limits. Once traction loss is too great, the system can be overwhelmed, causing a more sudden loss in traction than what a mechanical differential would do. In other words, you might spin more suddenly than with a mechanical diff. Also, the electronic control does not provide the same feedback to the driver and the same confidence that a mechanical differential does. Thus controlling the car is more difficult than it would be with a mechanical diff.

Ultimately, there is no huge difference in traction availability between the mechanical and electronic differentials. The biggest difference is in the way the car "feels". This is mostly evident exiting corners under heavy throttle. This is where the mechanical differential shines.

Because the differential system uses your brakes to aid traction, excessive heat and wear may be generated on your rear brakes during track driving. A mechanical LSD can help reduce this.


Do I need a mechanical LSD for....

... daily driving? No.

... "spirited" canyon driving? No. If you're regularly overwhelming the electronic differential on public roads, please start autocrossing or track driving your car instead.

... drag racing? Maybe. The electronic differential is very good providing straight line traction. A mechanical LSD is likely not going to make a big difference here. On the highest levels of the sport, maybe an LSD would make a difference. At that point you may be better off with a locking one instead though.

... track/autocross? Maybe. BMW's differential braking system works rather well even for autocrossing or track driving. Don't be afraid to track/autocross your car in stock trim. A mechanical differential will make a big difference in controllability and confidence here so there is a definite benefit for track junkies and autocrossers.

... drifting events? Most likely. More control = better drifts.

---

Revisions:
2012-07-16 Added comment on brakes
2012-07-18 Removed friction comparison statement
Hi Int2str,

Do you have wheel speed data also?

Thanks

Joao
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      08-05-2015, 11:10 PM   #110
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Quote:
Originally Posted by Zombie1 View Post
I have not found out how to code it out yet, but it hasnt kicked in once to my knowlegde even with the pouring rain we had in New York yesterday. Maybe there is a fuse to pull to shut it off?
Has anyone figured out how to shut off or code out elsd yet? From my experience, shutting dsc and dtc completely off does not stop elsd or electronics from using the brakes, throttle cuts, timing cuts and boost reduction to keep the car in line under heavy throttle especially with high boost applications. Going WOT from a stop leads to power reduction for me mostly in 1st gear with all nannies off verified through logs. I also have a mechancel LSD installed.
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