DTC option

[Claude]

Does BMW equiped with DTC option (Dynamic Traction Control) all (E34, E39, E60) have LSD differential, or this function assured by other means ?

[632 Regal]

no it does not, if it did then traction control couldn't independently control the rear wheels.
Does BMW equiped with DTC option (Dynamic Traction Control) all (E34, E39, E60) have LSD differential, or this function assured by other means ?

[Claude]

no it does not, if it did then traction control couldn't independently control the rear wheels.

Is it to say that if you disactivate the DTC function in the snow (or wet pavement) you may have a free spinning rear wheel meaning no traction at all ?

[Rus]

Yes. As regal said, those cars don't have an LSD. The only other differential available is the open diff, which would allow one wheel to loose traction without the DTC enabled. At least that's the logical conclusion.

[Claude]

Yes. As regal said, those cars don't have an LSD. The only other differential available is the open diff, which would allow one wheel to loose traction without the DTC enabled. At least that's the logical conclusion.

If it's really the case it's a real MINUS for us in northern region in winter time when stuck in the snow: With DTC ON you're not able to move because if a wheel start spinning... and it will... power is cut off so you'll not move for sure and with DTC OFF and an open differential if a wheel spin free... and it will... even if the other wheel could found / give some traction this one will not help because only the one that spin free (on ice for exemple) will rotate. Comclusion: One (in ours northern countries) will be better off with a car e/w LSD than with DTC That's my understanding, I am right ?

[bubba966]

I don't know about DSC, but on cars with ASC/ASC+T you can install an LSD into them and use both or just the LSD. ASC/ASC+T is pretty simple. It just sense when a wheel is slipping and in the case of the rear wheels applies the brake to the slipping wheel and it cuts the power back with a secondary throttle body. And LSD would prevent the ASC/ASC+T from kicking in most of the time as it'd prevent wheel spin a good bit.

DSC does more than that, but you should be able to install LSD's in DSC equipped cars. The E39 M5 has DSC & an LSD. Don't see why you can't add an LSD to an E39 equippe with DSC.

[Claude]

I don't know about DSC, but on cars with ASC/ASC+T you can install an LSD into them and use both or just the LSD. ASC/ASC+T is pretty simple. It just sense when a wheel is slipping and in the case of the rear wheels applies the brake to the slipping wheel and it cuts the power back with a secondary throttle body. And LSD would prevent the ASC/ASC+T from kicking in most of the time as it'd prevent wheel spin a good bit.

DSC does more than that, but you should be able to install LSD's in DSC equipped cars. The E39 M5 has DSC & an LSD. Don't see why you can't add an LSD to an E39 equippe with DSC.

I've ask the dealer he said : M3 and M5 models are e/w LSD diff but all other's with regular (open) diff.

[bubba966]

On the '95 540i M-Sports both LSD and ASC+T were options. I do believe that a few cars have both. Mine has ASC+T, and I've got an LSD sitting around to put into it at some point. No big hurry as I don't really need LSD. Need good winter tires more than that as the ASC+T set to snow mode actually works pretty decently.

[fin]

Try driving up an icy drive with ASC + T. Never make it up. The rev limiting feature kicks in and kills any momentum. It needs to be disabled (Search forum for how) and then you can do it.

Disable the stupid system and use your parking brake as limited slip if your rear is slidding around.

And put in the LSD like BMW should have done in the first place.

Cheers,

Fin

[Ross]

Isn't there a way to disable the power limiting feature of the ASC? Hold the button until the light flashes or something like that, I did it once but....Or does it disable the anti-lock and keep the trac control on?

[Tiger]

I thought there always is a way to turn off that traction control... even on the older BMW... isn't that the switch by the gearshift is for?

[Claude]

Try driving up an icy drive with ASC + T. Never make it up. The rev limiting feature kicks in and kills any momentum. It needs to be disabled (Search forum for how) and then you can do it.

Disable the stupid system and use your parking brake as limited slip if your rear is slidding around.

And put in the LSD like BMW should have done in the first place.

Cheers,

Fin

That's exactly what i thought: 1) The traction control ON would keep the car at the same place stuck and 2) If you put the traction control OFF but what you have is only a regular (open) type differential you'll not be better off because only the spinning wheel will rotate 3) the best would be to have an LSD diff, that would really help when the traction control is put OFF.

BUT it appears that at least recent versions of automatic traction control would put the break on the spinning wheel permitting the other one to propel you if it could get some ground resistance / traction. If it really works like that the automatic traction control does almost an equivalent job as the LSD diff would have done. But is this only theory ?? I don't have this option so i can't say, that was the reason of my first question.

[repenttokyo]

my 1991 525i has an LSD and no ASC/DSC.

In my lincoln, the traction control would brake the spinning wheel and allow power to flow to the wheel with traction. this was back in 1994.

[bubba966]

Isn't there a way to disable the power limiting feature of the ASC? Hold the button until the light flashes or something like that, I did it once but....Or does it disable the anti-lock and keep the trac control on?

Yup, that's the "snow mode" (as I call it anyways) that I referred to above. Press and hold the ASC button until the light turns off. Takes 8-10 seconds or so. You'll know it's in that mode as further pressing of the button no longer illuminates the ASC light in the dash.

The throttle control portion of the ASC system will be turned off. And it will stay in that mode until the car is shut off and restarted. Then you can get up icy hills.

Oh, and I mentioned this on my local CCA board when it was nasty slick out around here and it appears that this doesn't work on E36's that have ASC+T. I think it does work on E32's though. And it's worked on all of the E34's I've tried it on.

[bubba966]

That's exactly what i thought: 1) The traction control ON would keep the car at the same place stuck and 2) If you put the traction control OFF but what you have is only a regular (open) type differential you'll not be better off because only the spinning wheel will rotate 3) the best would be to have an LSD diff, that would really help when the traction control is put OFF.

BUT it appears that at least recent versions of automatic traction control would put the break on the spinning wheel permitting the other one to propel you if it could get some ground resistance / traction. If it really works like that the automatic traction control does almost an equivalent job as the LSD diff would have done. But is this only theory ?? I don't have this option so i can't say, that was the reason of my first question.

If you put the ASC+T system into the secret "snow mode" I described it mimics the effect of having an LSD. It's not quite as good as having a true LSD as it's applying the brakes slightly to the slipping wheel in order to send power to the wheel that's not slipping. But it does work.

Which is why adding an LSD to an ASC+T car would be beneficial. The LSD would take care of the first 25% of your power output, then the ASC when set to the proper mode would handle things after the LSD started slipping.