2WD to 4WD with an AUTO Gearbox

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Sat, 18/12/2010 - 18:00
HVD-EVS
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Location: UK

Could somebody please clarify whether it is always necessary to shift to neutral before changing from 2WD to 4WD with an auto gearbox? Or are there some exceptions i.e. at very low speeds? Thanks

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Sat, 18/12/2010 - 20:57
#1
Grendle
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Re: 2WD to 4WD with an AUTO Gearbox

 Always neutral. Mine won't move if i forget i'm in my 463 not my manual 460 (that will).

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Sun, 19/12/2010 - 00:53
#2
Pistonhead
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Location: Loughborough
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Re: 2WD to 4WD with an AUTO Gearbox

Remembering in the 460 chassis, the vehicle is normally in two-wheel drive mode.  Selecting  four-wheel drive, can be achieved in gear, provided the vehicle is at walking pace.  So, from two-wheel drive, (i.e. given the standard 'H' configuration of a manual gear box, where 1st gear is at top-left, 2nd gear is at bottom-left, 3rd gear is at top-right, 4th gear being at bottom-right of the 'H' configuration), on the transfer box (t/box) selector, we start from normal two-wheel drive; lever at the 2nd gear position, moving the selector to 1st gear position selects four-wheel drive, but in HIGH ratio.

Sliding the t/box lever across to the right hand side gives the same four-wheel drive mode in high ratio.  Here, is where the may or may not come-in to play.  Still at walking pace, try to select four-wheel drive but this is now selecting LOW ratio. If the gear will not shift, then you need to select neutral on the gear box (manual or auto. gearbox), try again shifting to four-wheel drive, low ratio.

After the selection, re-engage drive gear and keep on driving.  On the other hand, if the lever does shift into four-wheel drive, low ratio, then you still keep on driving......

Cheers,

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Sun, 19/12/2010 - 20:44
#3
MG463
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Re: 2WD to 4WD with an AUTO Gearbox

Hello HVD-EVS,

G-Wagen 460 models are equipped with a selectable 4 wheel drive system, which allows the engagement of the front axle at any vehicle speed, provided that the rear wheels are not spinning.
Normally the vehicle is in two wheel drive mode (rear axle engaged).
4 wheel drive mode has two options, hi-range (or on road ratio) and low-range (or off road ratio).
Shifting between the two requires the brief interruption of power flow from the engine to the transmission, either by depressing the clutch pedal (manual gearbox) or by selecting N(eutral automatic transmission).
In any case, care should be taken in order not to exceed the permissible engine speed by engaging low range (effectively if speed is kept constant and the same gearbox ratio is kept, engine speed more than doubles in the low-range).

Regards

Michael

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