[G30M]

just wondering if anyone knows?
on the protool front wheel torque monitor it appears it's virtually full time RWD but that doesn't seem right ...

[HighlandPete]

Originally Posted by g21

just wondering if anyone knows?
on the protool front wheel torque monitor it appears it's virtually full time RWD but that doesn't seem right ...

My reading, AWD "on demand" is likely based on the model. Whether M-Performance models are set up different, than bread and butter models, it is hard to establish the facts. BMW definitely state some models are RWD, with AWD on demand.

As an example, BMW clearly state for the M240i;

In driving situations where all-wheel drive is not necessary, the power from the inline 6-cylinder engine is sent to the rear wheels only.

For the G20 M340i, BMW state;

The system’s rear-biased setup helps to produce the driving experience expected of an M car, and is especially pronounced with the Driving Experience Control switch set to SPORT or SPORT+ mode.

Plus, the G-series models using the ATC13-1 transfer box have an 'efficiency' mode, which again favours RWD function.

Examples for the G12 or G30, where BMW state;

G12 material:

Efficiency Mode is always used when there is no all-wheel drive request from the DSC control unit and the multidisc clutch is therefore open.

G30 material:

Efficiency Mode allows a reduction in consumption thanks to activation of AWD functionality when it is needed. The torque distribution towards the front wheels can be completely cut-off in driving situations where all-wheel drive is not needed.

[Burrcold]

Pretty sure the xdrive set up in the G20 is 40/60 (front/rear) split while under standard load. Slip detection sends up to 85% of power to the rear, but never 100%.

[HighlandPete]

Originally Posted by Burrcold

Pretty sure the xdrive set up in the G20 is 40/60 (front/rear) split while under standard load. Slip detection sends up to 85% of power to the rear, but never 100%.

Have you a source for those figures?

BMW detail a 50:50 ratio (with the clutch fully locked up), in many of the latest technical details. Rather than 40:60 of previous setups. With 100% torque available to the rear wheels when the transfer clutch is open. A theoretical 100% of 'available torque' to the front axle in slip conditions.

[Burrcold]

Originally Posted by HighlandPete

Have you a source for those figures?

BMW detail a 50:50 ratio (with the clutch fully locked up), in many of the latest technical details. Rather than 40:60 of previous setups. With 100% torque available to the rear wheels when the transfer clutch is open. A theoretical 100% of 'available torque' to the front axle in slip conditions.

It could have been from the previous gen of xdrive I don't remember, but I have not seen anything from BMW that confirms 100% of available torque can be transferred front or rear. Just because the transfer clutch is open, doesn't mean the nannies will allow full power to go in either direction.

Anyway, my point was to refute a previous comment that the M340i xDrive is RWD unless it detects slip (basically the opposite of a FWD AWD system). Unless something has changed?

[SenorFunkyPants]

The M xdrive version may differ from versions in other models.
In the M xdrive version (fitted to F90 M5, G8x M3/4 etc) the car is in RWD unless certain control parameters are exceeded.
The principle one being slip detected at the rear wheels when excess torque is sent to the front wheels. Others include slip at the front wheels, yaw and steering angle.