I know what you mean (it's just as crappy in Calgary this week)!

It's only my 2nd winter, and with these Nokian WR G2's, while I still have to be careful, it's been magical. I lol'd while in the DQ drive thru -- it has an icy uphill portion, and the tahoe with winter tires in front of me kept spinning its tires (lady kept gunning it), and took about 4 tries to get up but when it was my turn I casually drove up to the window, paid and was on my way.

 

^^ I love passing sport utility vehicles when there is snow on the ground. Last winter I was plowing snow with my front end, had the crappy stock A10s on, and was still getting around better than most of the SUVs on the road.

 

its not that hard to understand. one key thing to understand is that a differential has to do with wheel speeds, not torque.

 

http://www.youtube.com/watch?v=F40ZBDAG8-o

best link..old but good

 

Oh snap; I swear I saw that back in HS lol

The key to understanding is that just like electricity, your power will follow the path of least resistance. Our torque split is 50:50; when slippage occurs, power is going to naturally go to the wheels with the least traction (path of least resistance). The center differential locks to enforce that 50:50 (to keep, say, the spinning fronts from stealing power from the rear), and the 3 ACD modes determine the behavior of the center diff in our AWD system.

The helical front and viscous rear diffs accomplish the same thing but in a L/R fashion but in different ways (the helical front relying on clutches, the viscous rear locks via the fluid heating up during slippage).

 

the torque applied to both wheels is the SAME in an open diff. the TOTAL torque to both wheels is limited by the wheel with less traction. if one wheel is in the air and the other on the ground, the torque to both wheels is the same. that simply cannot change. why the car doesnt move is because the toque being applied to the wheel on the ground isnt enough to move the whole car. the torque applied to the wheel in the air simply makes it spin.

and why is the total torque limited? because the total torque cannot be more than twice the amount it takes for one wheel to break traction. if one wheel is in the air, then the amount of torque it takes to spin that wheel is very minimal and thus the other wheel on the ground MUST have the exact same amount applied to it, way too little to move a car.

another way to see it is that one wheel can only spin twice as fast as the other wheel. the total torque that can be applied to both wheels is the amount that it takes to achieve that state, where one wheel spin twice as fast as the other. so as you can see, if one wheel is in the air, you dont need a lot of torque to spin it twice as fast.

so what happens when we lock the diff? you are preventing the wheels from spinning at different speeds, and in doing so you are preventing the wheels from ever going into that state where one wheel spins twice as fast as the other. in essence you are raising the total torque limit. with the raised limit, you can finally apply enough torque to that one wheel on the ground to move the whole car.

as for a center diff, its basically the same. think of both front wheels as one unit, and both rears as another. the center diff deals with wheel spin and total torque between both front and rear units. the front diff further deals with the front left/right wheels, as does the rear diff with the rear left/right wheels.

this is my understanding of the matter, if its wrong in any way please correct without bashing there is always an exception to the rule so this is a basic way to view simple differentials. for instance torsen diffs use a complex set of gears that CAN vary torque between wheels. how much depends on how the gears are cut, etc.

 

Wow... That actually made it really simple.. lol

Great posts guys!

 

Nicely written

 

I think the OP was talking about Power Distribution.

Even though its locked at 50/50, changing the button on the center console does alter the behavior and the balance of the car, especially at its limits.

As far as my stock RA (stock except for "aftermarket" tires, lol the yoko A10 sucked) it shows understeer at limits while in TARMAC (understeer more evident, feels like very little power in the rear) its nicely balanced for serious driving in GRAVEL (feels like 50/50 power/TQ split and I personaly like this mode most, but I use TARMAC for DD). SNOW mode helps the car rotate better and induces oversteer at the limit.

All this is based on my observations and in DRY weather. Your milage may vary BYE!

 

was is this always a question. I though it was more of how the car preforms and sends the power to the tires.

In tarmac mode it you feel all power to all tires just accelerate and you feel it.
Gravel makes the rear tires have more power put it in that mod acclarate and you will feel it
do the same for snow and get front wheel power.

AWC controls the where the center diff or puts the power

tarmac: good for street and drag
gravel: RallyX and Drifting and wet conditions
Snow: Well i test this out in a snow storm in New Mexico its a beast in the snow i was doing like forty and still had traction (snow tires really help)

 

This is NOT right.

Its always 50/50 split. The ACD only changes the locking of front and rear tires (whether they spin together or not). Tarmac locks them together quicker...snow leaves them open (spin different).

AWC is where the power goes per corner.

 

FTFW. That's it.

 

im pretty sure this is incorrect

 

The document linked earlier in this thread is a direct link to a Mitsubishi Engineering printout that states it is 50/50 all the time.

 

as Keifer stated, this is wrong.

Please read the tread and attached articles before you try to be a hero.