LSD......

[0002s]

Originally Posted by MihaSLO

Why would E-Diff work in straight line?
The wheels are rotating at the same speed, whether in corner they don't, and that is way you need LSD, to stop rotating them at different speed.

When you are hammering it in straight line on same surface under both wheels, E-diff won't come in play.

As soon as you spin a tire the EDIFF will brake it to let the other tire get traction. It will slow you down...how much....???? How much you going to spin with 300 ft/lbs of tq.

[Swift135]

Originally Posted by 0002s

E-Diff has to slow the car down on 0-??? runs. It's applying some braking to control the torque spin.

This could be why 0-XX times are slower than expected on in some publications. 335i doesn't have this so the tester are throttle managing the torque rather than braking managing.

Also...99.9999% of these cars will never be tracked or for than matter pushed to the point where the need for a true LSD will come into play.

The mags are making note of the under steer because they are pushing the car to it's limits in a corner on a track. It's absolutely NO SUPRISE that a car with smaller front tires and ride friendly sways is going to under steer.

Unless you know how to drive through a corner you are going to scrub under power or over steer and spin regardless of an LSD.

80% sweeping corners getting on to the freeway doesn't need LSD.

In fact you are a safer with under steer vs. spinning. I also would not want to give up ride quality for the ability to shave a few 1/10s of a seconds off track times when 99.9999% of my driving will not be done on a track.

It seems we are all complaining about a feature that will not get used often enough to justify the downsides.

-jm2c

There are two problems with this set up for me:

1. Two different sizes of tires means no tire rotation
2. E-Diff has to slow the car down some 1/10's of a second from the a stop and will wear brakes pads out prematurely if one drives like a bat out of hell all the time.

From what I have heard the e-diff is only active when the DSC is turned off. Most people would do 99% of their driving with the DSC left as it is when the car is started (ie DSC on).
If you are going to drive around with your finger on the DSC button and revving the ring out of the car than getting new brake pads will be the least of your worries?

[larryn]

Originally Posted by 0002s

As soon as you spin a tire the EDIFF will brake it to let the other tire get traction. It will slow you down...how much....???? How much you going to spin with 300 ft/lbs of tq.

Don't you mean "As soon as you spin a tire the EDIFF will brake it to let that tire get traction". It does nothing to the other tire. If it had traction, it lets it continue to have traction, and slows dow the spinning wheel so that it regains traction. Since this is in milliseconds, it should not allow the inside tire to smoke, and would not slow you down.

[0002s]

Originally Posted by larryn

Don't you mean "As soon as you spin a tire the EDIFF will brake it to let that tire get traction". It does nothing to the other tire. If it had traction, it lets it continue to have traction, and slows dow the spinning wheel so that it regains traction. Since this is in milliseconds, it should not allow the inside tire to smoke, and would not slow you down.

Yes... got it reversed.

I still think it will slow you down though. The braking doesn't stop the engine torque.

We shall see what it does once the car is actually out.

[0002s]

Originally Posted by Swift135

From what I have heard the e-diff is only active when the DSC is turned off. Most people would do 99% of their driving with the DSC left as it is when the car is started (ie DSC on).
If you are going to drive around with your finger on the DSC button and revving the ring out of the car than getting new brake pads will be the least of your worries?

So the e-diff is not on when DSC is on?

[mikeo]

Originally Posted by 0002s

So the e-diff is not on when DSC is on?

My understanding is that eDiff works all the time, even when DSC/DTC is turned completely off.

[BMWeber]

Originally Posted by mikeo

My understanding is that eDiff works all the time, even when DSC/DTC is turned completely off.

the ediff and dsc/dtc are the same thing just different levels
of interference from the computer.

[atr_hugo]

And since one can be turned off, shouldn't the e-Diff be able to be turned off? I asked that question in Chicago - didn't get a real answer. ; -)

If it's software, and you can turn off some of the software, there has to be some Orphan Annie decoder secret that turns it off completely. (Hopefully, that'll be our software alchemists charge. ; -)

[ttdmac]

Not sure if BMW would want ediff to be turned off if it is supposed to imitate a mechanical LSD. Not like you can opt not to use a mechanical LSD on a whim.

True that once someone is able to decipher the software they may be able to intercept code and effectively shut off the ediff, however we'll just have to wait and see.

[atr_hugo]

The only reason I'd want the e-Diff code off is if I install a mechanical LSD - otherwise it'd be left on.

[scottn2retro]

Originally Posted by atr_hugo

The only reason I'd want the e-Diff code off is if I install a mechanical LSD - otherwise it'd be left on.

Agree. Now in that case, to turn it off, and I'm speculating, it may be something like on our race car, where when we disconnect one of the sensors the system uses, it keeps the system disabled.

[O-cha]

You guys win I admit defeat.

Some experienced drivers, occasionally switch the DSC or DTC off, to obtain maximum
power and maintain vehicle speed while maneuvering through tight corners. They then
complain that without a differential lock too much power is lost through the driving wheel
on the inside of the bend which is carrying the smallest part of the load. If it loses grip,
the DSC reacts by applying the brakes to regain traction and/or limiting engine torque by
shutting off injectors. This results in a loss of power in mid-corner.

In order to satisfy that demand on the part of performance-oriented spirited drivers, as of
March 2008 the 135i will be fitted with the NEW DSC function program that simulates
the action of a mechanical differential lock. The system uses the typical BMW open type
differential and is comprised solely of an electronic intervention program inside the DSC.
When the vehicle is in tight bend the DSC applies the brakes the spinning (inside) driving
wheel, the torque is then transmitted to the outside wheel which is carrying most of the
load, optimizing power and maintaining vehicle speed trough the corner. The new function
implemented in the DSC control module is thus, in effect, DTC without modulation
of engine output. The DSC and DTC functions are unaffected by it.

In comparison with a mechanical differential lock, the advantage of the new DSC program
function is more than just the fact that it is substantially more cost effective. Whereas a
mechanical differential lock is permanently active, this DSC Function only comes into
action only when required and if the DSC/DTC is switched off. Nor does it add to the
vehicle weight and fuel consumption.

Furthermore, the function does not affect handling stability in DSC or DTC mode and the
familiar understeer tendency produced by mechanical differential locks is also avoided.
The feature will also be introduced on BMW 3 Series models with higher performance
engines at a later date.

[larryn]

O-cha, trolls don't come back and admit defeat. Takes a decent guy to do that.

There's all kinds of cool stuff that we learned today from that document that Rook posted this morning. Add one more cool thing to the list.. O-cha is okay.

[0002s]

Originally Posted by O-cha

Some experienced drivers, occasionally switch the DSC or DTC off, to obtain maximum
power and maintain vehicle speed while maneuvering through tight corners. They then
complain that without a differential lock too much power is lost through the driving wheel
on the inside of the bend which is carrying the smallest part of the load. If it loses grip,
the DSC reacts by applying the brakes to regain traction and/or limiting engine torque by
shutting off injectors. This results in a loss of power in mid-corner.

In order to satisfy that demand on the part of performance-oriented spirited drivers, as of
March 2008 the 135i will be fitted with the NEW DSC function program that simulates
the action of a mechanical differential lock. The system uses the typical BMW open type
differential and is comprised solely of an electronic intervention program inside the DSC.
When the vehicle is in tight bend the DSC applies the brakes the spinning (inside) driving
wheel, the torque is then transmitted to the outside wheel which is carrying most of the
load, optimizing power and maintaining vehicle speed trough the corner. The new function
implemented in the DSC control module is thus, in effect, DTC without modulation
of engine output. The DSC and DTC functions are unaffected by it.

In comparison with a mechanical differential lock, the advantage of the new DSC program
function is more than just the fact that it is substantially more cost effective. Whereas a
mechanical differential lock is permanently active, this DSC Function only comes into
action only when required and if the DSC/DTC is switched off. Nor does it add to the
vehicle weight and fuel consumption.

Furthermore, the function does not affect handling stability in DSC or DTC mode and the
familiar understeer tendency produced by mechanical differential locks is also avoided.
The feature will also be introduced on BMW 3 Series models with higher performance
engines at a later date.

WOOT.. :roundel: ..that is what mechanical LSD does....

[larryn]

That's excatly the same passage I quoted in the original thread. Great minds think alike. :wink:

[0002s]

YEP...it also doesn't use engine modulation either....WOOT WOOT

This means that a new set of tires with larger fronts could make this a real nice stock AutoX car....