When does AWD activate on a 2005 G35X?

[shooter71]

I have some odd sounds that appear to occur when I am baking up - kind of like the tire is rubbing on something during movement. I recently changed my rear and front breaks and did not recall hearing the sounds before. I jacked up one side, put the car in neutral and turned one tire by hand and did not hear anything unusual. I would now like to jack up both rear tires, start the car and put it in reverse to see if I can re-create the sound. However, with the AWD G35X, I am not sure if the rear tires not touching the ground, would the car think the rear is just spinning and would the front tires drive to begin to engage and then obviously make my car drive off the jack stands?

[sx moneypit]

Welcome to NICO!
Moved this to the G forums to get more feedback.

[biggie]

Some power goes to all 4 wheels all the time. The system is RWD bias, so normally runs 90% of power to the rear, until it feels slip in the rear then will sent as much as 40% of power to the front.

[kmckis1029]

based on my research the AWD has a 50/50 to 0/100 front/back torque split. when crusing on highway or any steady speed the car is almost 100% RWD. From a dead stop the AWD is almost 50/50 to about 12mph then sends torque to rear wheels. pressing the "snow mode" button forces a 50/50 torque split up to about 20 mph, while also deading the throttle to help reduce slip from the driver over throttling from dead stop in slippery conditions, and then resumes normal operation.

upon detecting slip the AWD system will direct torque to the front wheels up to the 50/50 split while also using the brakes to "vector" torque to individual wheels. (I've noticed on both my AWD Gs that the rear brake pads wear down quicker than the front pads because of their smaller size and the AWD using the brakes to "vector" torque to individual wheels) (the GTR's "pro" version of this AWD system dosent need the brakes to vector torqe to indivual wheels)

knowing this infomation i asked the question of how does VDC fit into this picture as it also uses the brake pads in combination with throttle control to help "steer" the car when slipage occurs. From my research it seems that the AWD gets "first dibs" on correcting slipage, before throtle control is used by the VDC. Basically the AWD system focuses on traction, while the VDC focuses on the car going in the intended path with out over rotation (aka YAW, or doing a 360)

This all can be seen while driving with VDC off in slipery conditions, as the AWD system will get every bit of traction your tires will allow. BUT you can do 360s and spin tires all day... (well to a point VDC is never fully off, but rather gives your car high limits before it will kick in again, but thats another topic) Then turn on VDC and try and do the same thing in slippery conditions and its trottle control quickly ends any tire spin, and will literally stop any over rotation in its tracks. (its a buzz kill if you forgot to turn off VDC and you wanted the over rotation)

with both systems on its very hard to lose control of the car past just running into something, if you have the space the car will correct it self to what it calculated your intendent path to be based on your sterring input. Its pretty amazing.

[kmckis1029]

i would suspect the car drives off jack stand...

also noted from tracking my car, if you hold brakes all torque is shifted to rear wheels... (i wouldnt try this on jack stands) This makes since as the brakes are used to "vector" power to individual wheels. (e.g. brake left rear tire and right rear tire gets more torque.)

here is me in my old 2005 G35x brake launching my car with VDC off, observe/listen the rear wheels spining and front wheels stopped. then AWD fuctions normally once brakes released.

[youtube]http://www.youtube.com/watch?v=vPMKaCteZu8[/youtube]