4WD FULL TIME or PART TIME when driving on beach/sand dune?

[FoxChung]

Hi,

When driving on beach or sand dune, should I use 4WD Full time or 4WD part time please? I normally use 4WD FULL TIME.

[Wooders]

On sand you DEFINATELY want PART-time.
Full time is for use ON-Road or high friction surfaces.

[FoxChung]

On sand you DEFINATELY want PART-time.
Full time is for use ON-Road or high friction surfaces.

Thanks for your reply, Wooders, Btw, how does 4WD Part time improve compare with 4wd full time when driving on sand?

[Antz]

Part time (when in 4wd) will give an equal 50/50 torque split to the front and rear axles. In Full time that split is variable so on the sand in Full time you only need one wheel to lose traction and the vehicle will not move forward. In part time, you need two wheels (one on the front axle and one on the rear) to loose traction before you stop.

[FoxChung]

Part time (when in 4wd) will give an equal 50/50 torque split to the front and rear axles. In Full time that split is variable so on the sand in Full time you only need one wheel to lose traction and the vehicle will not move forward. In part time, you need two wheels (one on the front axle and one on the rear) to loose traction before you stop.

I am bit confused, so, is that mean 4WD FULL TIME good for driving on sand or PART TIME?

[Wooders]

What Antz is saying is ;

FullTime 4wd has center differential action - ie the front & rear diffs are allowed to turn at different speeds. This is becuase on road the rear of a vehicle travels less distance that the front - just like the inside wheels travel less distance than the outside wheels....make sense so far?

Ok Now that differential action means that if one end of the vehicle losses traction, all the power will be transmitted to that differential - instead of the diff with more traction.......

Then because the standard differentails are what we call "open" or "unlocked", only one wheel on the differential needs to loose traction and ALL the power that could have gone to any of the other 3 wheels is now transmitted to that one bogged wheel......
Again I hope that's clear?

NOW if we look at PART-TIME 4x4, the centre differential is "locked" so now the front & rear differentials must travel at the same speed (hence why you must NOT drive onroad in Part-time 4x4).......The locked centre diff now means that one front wheel and one rear wheel must now loose traction before you get bogged....

feel free t ask any questions if you don't understand as its pretty important stuff for a 4x4er.

[FoxChung]

What Antz is saying is ;

FullTime 4wd has center differential action - ie the front & rear diffs are allowed to turn at different speeds. This is becuase on road the rear of a vehicle travels less distance that the front - just like the inside wheels travel less distance than the outside wheels....make sense so far?

Ok Now that differential action means that if one end of the vehicle losses traction, all the power will be transmitted to that differential - instead of the diff with more traction.......

Then because the standard differentails are what we call "open" or "unlocked", only one wheel on the differential needs to loose traction and ALL the power that could have gone to any of the other 3 wheels is now transmitted to that one bogged wheel......
Again I hope that's clear?

NOW if we look at PART-TIME 4x4, the centre differential is "locked" so now the front & rear differentials must travel at the same speed (hence why you must NOT drive onroad in Part-time 4x4).......The locked centre diff now means that one front wheel and one rear wheel must now loose traction before you get bogged....

feel free t ask any questions if you don't understand as its pretty important stuff for a 4x4er.

Hi Wooders,

I start to understand now. Please correct me if I am wrong as I am no good in these technical 4WD terms.
4WD Part time locks all 4 wheels and they have to spin at the same speed. If driving on sand terrain as the traction is low, one front wheel and one rear wheel could easily spin and maintain at the same speed as the other two wheels, and it won't damage the driveline.
For 4WD Full time, all four wheels can be spinned at different speeds. Again, if driving on sand, it won't make any problems since all four wheels can spin at different speeds no matter you make turns.
If that the case, both 4WD FULL TIME or PART TIME can be used on sand terrain. and which one is preferrable? and why please?

[Steve F]

In fulltime, if one wheel looses traction all the power will go to that wheel and you will stop, it doesn't matter if it is front or rear. This is because the centre differential is 'unlocked' think of it the same as the differential in the front or rear axle.

In part time you must loose traction to one front and one rear wheel before you stop moving, so Part time is better on loose surfaces.

Cheers
Steve

[FoxChung]

Thanks for all your help and explanations. I am alot clear now. cheers.