[zsapphire7]

So, around march 08 production cars the 3 series were equiped with an elsd where the brakes would be applied upon the slipping rear wheel to allow for transfer of tq to the other side even with all traction control off. I have a pre March 08 production car so i do not have the elsd. I was wondering, is it possible to program our cars to have this?

I was thinking that having this would be a fine addition to the quaife. Essentially in a 0 traction condition, the brakes would come in, but the quaife would be able to transfer 4-5x that to the outside wheel.

[DaFish]

Originally Posted by zsapphire7

So, around march 08 production cars the 3 series were equiped with an elsd where the brakes would be applied upon the slipping rear wheel to allow for transfer of tq to the other side even with all traction control off. I have a pre March 08 production car so i do not have the elsd. I was wondering, is it possible to program our cars to have this?

I was thinking that having this would be a fine addition to the quaife. Essentially in a 0 traction condition, the brakes would come in, but the quaife would be able to transfer 4-5x that to the outside wheel.

I also have a pre-march 335i. I would also like to discuss if we just did the quaife, do we even need the elsd? I heard great things about the quaife and would love to hear from someone that has a pre-march 335i and the quaife.

[zsapphire7]

its not need.. The only time the quaife has issues is when it loses full traction to the inside wheel since it multiplies the tq to the outside wheel. 0 times any number is still 0 and thus will behave like an open diff, minus any preload. The elsd will kick in at that time however and any braking tq applied to the inside wheel will be multiplied to the outside. Essentially u make the elsd much more efficient instead of an open diff only transfering an equal force to the outside wheel.

My thoughts are that the elsd compliments the quaife really well...

[Webz]

You might try posting this in the drivetrain section or maybe pose a similar question in the thread related to the Wavetrac peice (found here: http://www.e90post.com/forums/showthread.php?t=270788)

I would like know the answer as I have an elsd and looking at the Quaife also.

[chaz58]

Yeah, e-diff would only make a difference if there was zero traction on one of the wheels (i.e. in the air).

My Audi basically did this. If there was zero traction at a wheel, it would brake that wheel (at speeds <20mph) so that you wouldn't be stuck even though you have AWD.

In my experience, the e-diff only makes a difference if you press the DST button (and then it makes a huge difference).

Originally Posted by zsapphire7

its not need.. The only time the quaife has issues is when it loses full traction to the inside wheel since it multiplies the tq to the outside wheel. 0 times any number is still 0 and thus will behave like an open diff, minus any preload. The elsd will kick in at that time however and any braking tq applied to the inside wheel will be multiplied to the outside. Essentially u make the elsd much more efficient instead of an open diff only transfering an equal force to the outside wheel.

My thoughts are that the elsd compliments the quaife really well...

[DJKhan85]

How do you know if your car has an e-diff or not? I it listed when i run the vin? I have a february 08 build btw...

[stressdoc]

e-diff is the most absurd mislabel ever. It is brakes and power cuts. All E9xs have this, it's termed DSC/DTC. The post 03/08 version is programmed differently. The later version is not what I want because it is more invasive and apparently does not completely turn off some braking functions; IMO the pre 08 version works fine with all stages of DSC/DTC. Quaife or other LSD is great regardless of which version you have.

[zsapphire7]

actually ediff is the best compliment for a quaife.. and does not cause throttle cut off.

one way u can test for ediff is by holding down the DSC button for 5 seconds to turn all traction control off. then find a dip or something to get one rear wheel in the air. if your car gets stuck... u don't have ediff software.

[chaz58]

Not true, my friend.

the e-diff was added march '08, and is not at all like what the earlier cars had. Earlier cars really need a Quaif – the latter cars would only show minimal benefits from a Quaif.

have you ever driven both cars hard with the DTC turned down or off? The earlier cars have the horrid “1 wheel” spin of an open differential. The latter cars behave very similar to a viscous LSD. It is seamless and not at all invasive. In road/track/Auto-X I have not found any down side to this. I do drive with DST turned down or off a fair amount of the time.

Yeah, I would rather have a Quaife than a viscous LSD or an e-diff, but that is a pretty minor difference compared to a completely open differential.

P.S. I liked your sig picture, but I still think it needs a fill flash to highlite that good looking (!) car you have - something like this below:

Originally Posted by stressdoc

e-diff is the most absurd mislabel ever. It is brakes and power cuts. All E9xs have this, it's termed DSC/DTC. The post 03/08 version is programmed differently. The later version is not what I want because it is more invasive and apparently does not completely turn off some braking functions; IMO the pre 08 version works fine with all stages of DSC/DTC. Quaife or other LSD is great regardless of which version you have.

[chaz58]

Originally Posted by DJKhan85

How do you know if your car has an e-diff or not? I it listed when i run the vin? I have a february 08 build btw...

Easiest way is to find some dirt/snow. Turn DTC all the way off. Accelerate in a straight line, and in a “J” turn. Do you leave two even streaks, or are you getting a lot of wheel spin on one wheel?

The fun way of course is to do some hard driving on a track (or somewhere safe). If you get a lot of inside wheel spin with DTC turned down or off, then you don’t have the e-diff.

Its not listed in the VIN. BMW didn't tell anyone when they did this, and it took some knocking on doors to get them to fess up to this change. I guess they didn't want to steal some lime light from the new introduction of the 1 series.

[Twilight1]

Originally Posted by chaz58

Easiest way is to find some dirt/snow. Turn DTC all the way off. Accelerate in a straight line, and in a “J” turn. Do you leave two even streaks, or are you getting a lot of wheel spin on one wheel?

The fun way of course is to do some hard driving on a track (or somewhere safe). If you get a lot of inside wheel spin with DTC turned down or off, then you don’t have the e-diff.

Its not listed in the VIN. BMW didn't tell anyone when they did this, and it took some knocking on doors to get them to fess up to this change. I guess they didn't want to steal some lime light from the new introduction of the 1 series.

I turned off the DTC today and brake torqued the car and left two even streaks of rubber for about twenty feet. Definitely not like any open diff I've ever seen.

[stressdoc]

My 2002 would leave two black strips before I put a LSD in it. So did my 2007 E90 335 before I put an LSD in it. I have driven pre- and post- 03/'08 335s. There are trivial differences with full DTC/DSC and partial DSC/DTC (quick button push). Long button push on pre- results in electronic nannies completely off. Post- keeps some braking when asymmetric wheel rotation is detected -- you can never turn DTC completely off in a post-. Get over it; there is no mechanical or electronic anti-slip mechanism in the post- differential. The final drive unit is exactly the same. "e-differential" is a minor software change in the DTC/DSC system. It steals the name of the real thing, an electronic limited slip differential that some Ferraris and Porsches have. You guys want to buy into the marketing BS, fine. Go racing with your "e-diff", especially off-road rallye racing.

Do most E9x drivers really need a LSD? Of course not. But you will find the M3 equipped with a real LSD.

To answer the Q regarding possibility of reprogramming, that is can of worms. I would guess that a new ECU might be part of the picture.

[Twilight1]

Originally Posted by stressdoc

My 2002 would leave two black strips before I put a LSD in it. So did my 2007 E90 335 before I put an LSD in it. I have driven pre- and post- 03/'08 335s. There are trivial differences with full DTC/DSC and partial DSC/DTC (quick button push). Long button push on pre- results in electronic nannies completely off. Post- keeps some braking when asymmetric wheel rotation is detected -- you can never turn DTC completely off in a post-. Get over it; there is no mechanical or electronic anti-slip mechanism in the post- differential. The final drive unit is exactly the same. "e-differential" is a minor software change in the DTC/DSC system. It steals the name of the real thing, an electronic limited slip differential that some Ferraris and Porsches have. You guys want to buy into the marketing BS, fine. Go racing with your "e-diff", especially off-road rallye racing.

Do most E9x drivers really need a LSD? Of course not. But you will find the M3 equipped with a real LSD.

I'm not doubting your word but both of my 2002s would only spin one wheel. I agree most E9x drivers don't need it.

[Twilight1]

OK, What I believe is going on is that the brake is still being applied to the spinning wheel even with the DTC turned all the way off.

[stressdoc]

One wheel, two wheels. Whatever.

What is awesome is a freakin' diesel burning rubber!

[Twilight1]

Originally Posted by stressdoc

One wheel, two wheels. Whatever.

What is awesome is a freakin' diesel burning rubber!

Totally agree! As I stated, what threw me off was even though the system was "off", it still brakes the spinning wheel.

Thanks for all the info!

[chaz58]

Glad it helped.

I had a awful lot of inside wheel spin on the '07 models I test drove extensively. It made me think seriously about getting another car. I decided to bite the bullet and get a quaife if it bothered me that much (thinking at the time it was $2K, it is really $4K if you have a stick (meaning you have a welded rear diff)).

Fortunately BMW fixed this problem for my needs. No inside rear wheel hanging in the air spinning like mad. To me this is huge. I've been driving mostly 330's and 328's (RWD, stick).

[chaz58]

Originally Posted by stressdoc

My 2002 would leave two black strips before I put a LSD in it.

In a turn??? That just doesn't make sense...

Originally Posted by stressdoc

You guys want to buy into the marketing BS, fine. Go racing with your "e-diff", especially off-road rallye racing.

Doc, with all due respect, I know of nothing written or in any type of marketing where BMW admits to having this in the 3 series. There is no marketing of this, none with the e90. The only exception to this is a written reply I have from BMW in my enquiries as to why the two cars drive so different.

Stressdoc, no one ever said an ediff was better than the M3 diff. None of us are racing our cars or doing rally racing. I have been doing autocross and track schools for 25+ years, and on my car the system works very similar to a viscous LSD, and not quite as good as a Torsen or Quaife.

Ether way, enjoy your car! :-)

[Alpina_B3_Lux]

Originally Posted by stressdoc

e-diff is the most absurd mislabel ever. It is brakes and power cuts. All E9xs have this, it's termed DSC/DTC. The post 03/08 version is programmed differently. The later version is not what I want because it is more invasive and apparently does not completely turn off some braking functions; IMO the pre 08 version works fine with all stages of DSC/DTC. Quaife or other LSD is great regardless of which version you have.

+1

It's just horrible. Cuts power more or less consistently when driving hard in the first three gears, on a track the car feels as if it hicupped continuously. I can't imagine who would really want this if you have the choice of getting a real torsen-diff. It may not be bad for the daily granny driver, but once you start adding power to your car or driving it a bit harder, you'll find it quite annoying. That is in fact THE reason why a Quaife is no. 1 on my wishlist right now.

Alpina_B3_Lux

[stressdoc]

To balance my perspective which could be interpreted as overly negative, I think BMW has done a wonderful job with DSC/DTC. Of course the relative asymmetry of traction is improved over older models such as the 2002. That said, DSC programming can never provide the benefits of an LSD, and IMO BMW has done nothing better than slap a band-aid on this Achilles heel of the 335. Not a big problem with the 328 on dry pavement, but for the 335 to perform to its potential a LSD is critical.