Possible to keep DTC on with DSC off?

[BassFace]

Hi

I've had my 3.0 SE Roadster for a while now and am getting a bit annoyed with the lack of LSD. Driving with DTC on is ok but frustrating at the same time, as it acts as a poor mans LSD but any fun is instantly killed by DSC intervening. Whereas driving with both DTC and DSC off is pretty pointless because on slower corners/road driving the inside rear wheel spins all the power away.

So - is it possible to switch off DSC but keep DTC engaged? I suppose i'm wondering if the DSC module can be reflashed (here's hoping)! I'm not that keen to pay £1k for a quaife LSD..

Cheers
Alex

 

[sam1832]

The tc kills power at any hint of a wheel spin

So even if you could run with just tc it would be just as much of a kill joy as soon as the wheels start to spin power is cut

and I would imagine you could be worse off, it would be like begging to drift with everything off then letting off of the accelerator it will snap back quick

Sent from my GT-I9300 using Tapatalk 2

 

[BassFace]

Ah right, yes of course it wouldn't work due to the TC. It's a shame they didn't offer a LSD option on the Z4 but I suppose they had to differentiate between the Z4 and the Z4M.

 

[LeeZ4MR]

Ah right, yes of course it wouldn't work due to the TC. It's a shame they didn't offer a LSD option on the Z4 but I suppose they had to differentiate between the Z4 and the Z4M.

I have often said it surprises me that bmw don't offer a LSD across the range of their more sporting/larger engine cars because as you say most people would enjoy a LSD alot, but it must be as you have pointed out that they want to separate the M cars from the rest of the range, which I think is a shame.

 

[sam1832]

Lsd would be great though

But also don't like the price tag

Even if it was an optional extra straight from the factory I wonder how many would be floating around with that extra ticked?

Sent from my GT-I9300 using Tapatalk 2

 

[LeeZ4MR]

Lsd would be great though

But also don't like the price tag

Even if it was an optional extra straight from the factory I wonder how many would be floating around with that extra ticked?

Sent from my GT-I9300 using Tapatalk 2

That's a fair shout, the costly options list is wallet wilting as it is so your probably right not many takers, I've had a LSD on three of my RWD cars I have owned & I would invest in one given the option I think.

 

[shawna]

Lets group buy an LSD?

What is it to fit a dog?

 

[Chiddy]

I like the group buy idea...

 

[bcworkz]

The tc kills power at any hint of a wheel spin

No, actually DTC mode in the Zed allows some spin. Full DSC mode kills power with wheel spin, and reels in the slightest drift. DTC allows wheel spin to a point, and allows a bit of drift before intervening. Then off is off. You're on your own. :driving:

Not really that important to LSD discussion, just wanted to keep the facts straight. Sorry if I'm being too pedantic.

 

[corsaire77]

Exactly, both DSC and DTC are pretty much the same, but the latter allows for more wheelspin up to a certain speed. Just a different reaction margin.

Anyway, I've talked to a '07 350z guy, who claimed that his car's electronics still emulated LSD with rear brakes with all the systems off. I did not have a chance to test it, though.

 

[BassFace]

As i understand it DTC brakes the inside rear wheel (i.e. the one that loses traction on acceleration out of a corner) to match the speed of the outside wheel which encourages oversteer, but once the car starts to move sideways the DSC cuts in and stops any fun. So DTC acts like a poor man's LSD but is hugely limited by DSC intervening. I know the 130i, 135i, and therefore possibly the E89 Z4 have an electronic LSD which must be en evolution of the DTC system, and may therefore be better. I may of course be talking absolute rubbish.

 

[shawna]

Is there a 2 stage switch off on them?

 

[bcworkz]

As corsaire77 said, DSC and DTC do the same thing, only the tolerance level for when the system intervenes changes. The modes are unfortunately named, causing endless confusion.

DSC is the default mode and is in effect when the car is started. Press the DTC button once to enable DTC mode, and the amber DTC lamp lights in the instrument cluster.

To turn off both DSC and DTC, from either mode, hold down the DTC button for about 3 seconds. An amber warning icon will light in the instrument cluster.

Both DSC and DTC mode will selectively apply the brakes to keep the car pointed in the right direction. The only difference is how much drift occurs before the system engages. The DTC mode allows more drift.

Both DSC and DTC will selectively apply brakes to the spinning wheel, and if need be, cut engine power to control the spin. The only difference is how much spinning is allowed before the system engages. The DTC mode allows much more spin. I've spun wheels quite a bit in DTC mode, I have yet to notice any power reduction, but I'm allowing that it could happen in extreme cases. Power reduction in DSC mode happens during almost any wheel spin.

 

[Woody]

Is that ^^^^ the same for the M aswell?

 

[shawna]

As corsaire77 said, DSC and DTC do the same thing, only the tolerance level for when the system intervenes changes. The modes are unfortunately named, causing endless confusion.

DSC is the default mode and is in effect when the car is started. Press the DTC button once to enable DTC mode, and the amber DTC lamp lights in the instrument cluster.

To turn off both DSC and DTC, from either mode, hold down the DTC button for about 3 seconds. An amber warning icon will light in the instrument cluster.

Both DSC and DTC mode will selectively apply the brakes to keep the car pointed in the right direction. The only difference is how much drift occurs before the system engages. The DTC mode allows more drift.

Both DSC and DTC will selectively apply brakes to the spinning wheel, and if need be, cut engine power to control the spin. The only difference is how much spinning is allowed before the system engages. The DTC mode allows much more spin. I've spun wheels quite a bit in DTC mode, I have yet to notice any power reduction, but I'm allowing that it could happen in extreme cases. Power reduction in DSC mode happens during almost any wheel spin.

Fantastic thanks for the explanation!

 

[mad4slalom]

the dsc in the m i think is over sensitive as that too dumps power way too soon , even when it is switched off it sometimes feels like it is still sapping power, dont know if i am imagining this or not, as supposedly with it off you are on your own,... I'm not so sure, any ideas :driving:

 

[bcworkz]

I don't know if the DSC/DTC is the same in the M, but I've never been shy about speculating. :roll: Much like the sport button operation, the basics should be the same. The design goals of each mode are still valid regardless of the model. Unfortunately, there's enough badge whores who buy Ms simply because it is the best and most expensive of the line, and haven't a clue how to get the innate performance from the car. So even Ms need a nanny mode.

If there's any difference, it will be only in the variance of the response curve. The "need" remains in either model, but driver expectation is different, hence different response. The raison d'être of DTC is to enable climbing snowy inclines, which hampers both models equally. The allowance for a bit more fun is only a side effect

As far as off not being off, it's certainly possible. My feeling is off is really off, at least in my non-M. I can't fathom Ms being otherwise. I've experimented with the various modes in a snowy car park, and in that situation, off certainly seemed like off. I've shifted up through the gears to an indicated 50mph, all the while the actual speed wasn't more than 10mph. But then we know that the system grows more restrictive at higher speeds, so perhaps I just wasn't going fast enough for the alleged not-off off override to take effect.

As far as feeling the power drop even when the nannies are disengaged, there's a lot going on when you are sliding around a corner, effects that are easy to feel are not so easy to attribute to a particular event. I'm more inclined to blame it on handling physics than some sort of not-off off mode.

I'd sure like to hear from someone that actually knows what they're talking about though.

 

[LeeZ4MR]

the dsc in the m i think is over sensitive as that too dumps power way too soon , even when it is switched off it sometimes feels like it is still sapping power, dont know if i am imagining this or not, as supposedly with it off you are on your own,... I'm not so sure, any ideas :driving:

My feels like its off totally when I switch it off, sometimes gets the back axle bouncing nicely & it will snap sideways with a few revs but when it's on it just holds the power back & for me makes it less predictable, I have said before that if you already have a locking diff like the M has why do you need traction control aswell.

I always drive mine now with traction off don't know if this is wise this time of year but its certainly fun!

 

[McKoval]

Dsc and dtc are not the same.
Dsc, in reality DSTC is stability and traction control, while dtc is traction control.
What it really meand that dsc not only controls the wheelspin but also tries to cope with the understeer.
On public roads dsc is undriveable while spirited driving while using dtc you cane spin the car preaty easily (in the wet)

TapaTalking

 

[corsaire77]

Not true in BMW's case, but the confusion is due to naming. Both stability and traction control ARE active in the DTC mode, however with a much more liberal threshold at lower speeds.

You can spin it in the wet, because the DTC reaction margin is so late that it can hardly cope with the spin.

http://www.bmw.com/com/en/insights/technology/technology_guide/articles/dynamic_traction_control.html

and here more about BMW's understanding of the two modes (especially page 17)
http://www.bmwclub.lv/files/06_E85_Chassis_Dynamics.001.pdf

One can prove it by a simple experiment:
Spin the car in the wet with all systems off, and you can recover only with the steering wheel. Spin it hard in the DTC mode, and halfway through the spin the somewhat belated stability control will kick in to put the car straight. It will do so even when you lift your foot off the accelerator, unlike a mere traction control measure.