[G30M]

the more i think about this the more I'm thinking - is there a technical document or explanation how Dynamic Traction Control works?

a while ago, in the M340i one rainy day and stupidly stuck it in Sport Plus, Sport Manual Mode and DTC

first bend and the tail happily and gently glided out of line and around to oversteer and I counter steered a little and immediately the car violently flung the tail over to the other side and oversteered the other way

and another counter steer but this time less angle and the computer straightened out the car

that was a very stupid thing i did but i'm thankful no oncoming cars as i had occupied both lanes in the process (should have thought thar through prior). i thought DTC would give a nice controlled drift around the bend.

but what did the computer do to violently swing the tail around? how was that achieved? i suspect the violent force was the hard braking of one or more wheels. but can't think of which one(s).

[HighlandPete]

Originally Posted by g21

the more i think about this the more I'm thinking - is there a technical document or explanation how Dynamic Traction Control works?

I think you need to expand your thinking around your experience to cover DSC. (DTC is a function within the DSC suite).

Worth googling "BMW DSC pdf" and you will find some of the original Technical Documents which describe and illustrate BMW's DSC function.

Specific to DTC. From BMW AG TIS.

Dynamic Traction Control (DTC)
DTC offers better traction as a trade-off against a reduction in stability in some circumstances. Consequently, its use should be reserved for exceptional conditions (driving in deep snow, for example).

The DTC function approximates to that of DSC with a slightly modified control strategy. DTC can be activated by deactivating DSC (DSC button).

DTC intervenes in the braking actions to imitate the function of a conventional differential lock.

Advantage: Higher traction is available with DTC.

Vehicle stabilisation intervention (e.g. reduced power output) is made slightly later than with DSC. This enhances traction with a slight loss of driving stability. Occasionally, a compromise is needed between vehicle stability and traction. This is especially true when accelerating and driving uphill on loose surfaces or in deep snow (= friction values demanding increased slip). DTC allows DSC to provide a high degree of vehicle stability while retaining sufficient traction.

Note: "intervention is made slightly later than with DSC".

Also remember tire grip and traction (lack of) can be causes the sudden 'snap' reactions. The base DSC functions then trying to rein you in.

[G30M]

Thanks so dtc is marketed for moving in snow and not for getting the backside out for fun. I've read people killing the transmission by doing this, so I guess it's true what bmw says, and we have just been misusing it.

I thought it was the same as MDM (M dynamic mode) M cars which, if I'm not mistaken is made for getting the backside out.

[HighlandPete]

Originally Posted by g21

Thanks so dtc is marketed for moving in snow and not for getting the backside out for fun. I've read people killing the transmission by doing this, so I guess it's true what bmw says, and we have just been misusing it.

I thought it was the same as MDM (M dynamic mode) M cars which, if I'm not mistaken is made for getting the backside out.

I first had DTC in my E91 wagon. Mainly used in snow, but when driving with purpose, DSC could intervene on rear wheel braking, as you got near the limits, (not playing with kicking out the back end, like on snow, but serious assessment of the handling dynamics).

I have one particular bend where if pressing on, due to the camber and need to quickly pull in to the bend, I sensed the flow of the chassis slightly unsettled by DSC intervention. This limit is not reached with DTC, the chassis is more fluid. This is all subtle stuff.

With my F11 the same happens as I push the limits on that particular bend. You just know the rear bakes are being used by the DSC. With DTC on, or Sport+ (which engages DTC in my model), I know the chassis is not controlled by any intervention in that same bend. Again this is all subtle and just sensed through the seat.

It is more like a RWD vehicle without any DSC or ESP fitted. Same for accelerating from standstill, there is more freedom before any DSC intervention.

If you push past the limits of traction and grip, you can be on your own if outside the parameters of what the reduced level of DSC can control.