AWD power sharing
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From: Great Mills, MD
AWD power sharing
How do our cars with AWD share the power front to rear? Is it always 50/50 power split? Is it 90/10 until the front tires slip, then shifts to 50/50?
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From: clevelnad
RE: AWD power sharing
i have heard that from a standing start you can spin the rear tires and not the front... has any one tried this? if that is tru then it can't be 40/60 all the time right??
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From: Great Mills, MD
RE: AWD power sharing
jvegas, with more weight on the front tires and less power, to me it seems possible that you would only be able to spin the backs and not the fronts.
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RE: AWD power sharing
the viscous coupling ( apparently only in the first 3 years ) will act as a limited slip, and very quickly stop the rear wheels from spinning.
Please try to do some googleing or searching on how differentials work. A 50/50 differential gives equal torque to both wheels.. this is the same for a rear, front or centre diff. The thing to learn is that it gives the LOWER amount of torque to both wheels. What I mean by this, is that if one wheel is on wet ice.. and it takes ALMOST ZERO torque to spin that wheel, then the other wheel gets the very same and equal ALMOST ZERO torque. This is typical on a front or rear differential on a 2 wheel drive car. Even in this old fashioned case.. the torque from the wheel that slips is given to the wheel that grips.... the advertising that uses that line is sooo ridiculous, because there is nothing unusual about that. What they fail to mention is that a slipping wheel has almost no torque to give to any other wheel.
On a 4WD car, there is also the centre diff (inside the transfer case) that does the same thing. Except that in our case the division is not 50-50 it is 60-40. So if it takes a very small amount of force to spin the back wheels, the Front wheels get only 80% of the torque, not an equal amount.
The viscous coupling is a friction device, and when the rear wheels spin (or alternatively the front wheels) then the VC creates extra torque for the diff to divide up.
THere is no magic to how these things work. Car sales people will all tell you that they put all the torque here or there..... but they never say for sure (and for sure they dont know anyway) if ALL the torque is ALL the torque genearted by the wheels that are slipping/gripping, or all the torque is from the effort to slip the viscous coupling, or if it is ALL the torque from the engine.
BEWARE of torque distribution discussions.. there is massive missinformation out there.
Please try to do some googleing or searching on how differentials work. A 50/50 differential gives equal torque to both wheels.. this is the same for a rear, front or centre diff. The thing to learn is that it gives the LOWER amount of torque to both wheels. What I mean by this, is that if one wheel is on wet ice.. and it takes ALMOST ZERO torque to spin that wheel, then the other wheel gets the very same and equal ALMOST ZERO torque. This is typical on a front or rear differential on a 2 wheel drive car. Even in this old fashioned case.. the torque from the wheel that slips is given to the wheel that grips.... the advertising that uses that line is sooo ridiculous, because there is nothing unusual about that. What they fail to mention is that a slipping wheel has almost no torque to give to any other wheel.
On a 4WD car, there is also the centre diff (inside the transfer case) that does the same thing. Except that in our case the division is not 50-50 it is 60-40. So if it takes a very small amount of force to spin the back wheels, the Front wheels get only 80% of the torque, not an equal amount.
The viscous coupling is a friction device, and when the rear wheels spin (or alternatively the front wheels) then the VC creates extra torque for the diff to divide up.
THere is no magic to how these things work. Car sales people will all tell you that they put all the torque here or there..... but they never say for sure (and for sure they dont know anyway) if ALL the torque is ALL the torque genearted by the wheels that are slipping/gripping, or all the torque is from the effort to slip the viscous coupling, or if it is ALL the torque from the engine.
BEWARE of torque distribution discussions.. there is massive missinformation out there.
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