Awd disabled with techstream
You say its minimum at 30%. 30% torque lets say is 1 third of car’s power. That would be 100hp to the front wheels. Something like a golf 3 hatchback. That’s enough to shoot the snow as high as the rear wheels. When its disabled it’s disabled. There isn’t even one asthmatic half dead horse to the front wheels, they are barely rolling along.
At full throttle below 4000rpm, even if the rear tires are spinning, with a nominal 30:70 split the fronts may only be receiving approximately 60 lbs/ft of torque, which is less torque than I use to secure my lug nuts and not guaranteed to spin a tire bearing a 1000lbs load, even on snow.
So, the clearance when assembling the clutch pack of the center diff is .4-.8mm. That's like a football field in mechanical adjustment tolerances.
I think he is actually accomplishing zero torque up front, and the hydraulic pressure signal to the clutch is being dumped back into the transmission pan instead of going to the center diff clutch. Further, there IS a return spring assembly in the clutch pack to push the piston away and allow the clutches to open fully.
FTM:
Hydraulic Control (Line Pressure Control)
(1) Line pressure for transmission control is also used by the transfer to simplify the transfer hydraulic system.
(2) Line pressure from the transmission is controlled by a modulator valve so that it does not rise above a specific level. This stabilizes hydraulic control of the transfer control solenoid assembly.
(3) Hydraulic pressure controlled by the transfer control solenoid assembly operates the control valve. The pressure also controls the slip status of the center differential limiting clutch by modulating the line pressure from the transmission in the transfer control solenoid assembly.
Transfer Control Solenoid Assembly
(1) The transfer control solenoid assembly is integrated with the electromagnetic section and the pressure modulating section. The spool pushes the pressure modulating valve in accordance with the electric current value that makes the electromagnetic section function. The pressure modulating valve then generates hydraulic pressure to resist the pushing force of the spool, thus making it possible to obtain hydraulic pressure proportional to the electric current value.
FAIL-SAFE
(a) The fail-safe function minimizes the loss of operability when an abnormality occurs in a sensor or a solenoid.
(b) For details, refer to the Repair Manual. (<- the manual doesn't explain much besides what I note below)
He can prove this by putting his car on some jack stands or a lift and putting it in gear. The fronts might slowly turn, but they're not going to match the rears at all if fourgs is right. Also, since he has a plethora of white stuff outside, he should just be able to get his car into AWD-off with TRAC and VSC off and be able to do a "burnout" with just the rears in a straight line. He should also be able to do some donuts easily. It looked like he couldn've in his video.
I wonder, with any car fully off then the front drivetrain would typically be free to spin, no? Two people should be able to grab the front tires and turn both the same direction freely with no hydraulic pressure to the clutch pack. If this is true, then this means it would be possible to disable the front end completely on a whim. You'd just need to cycle the ignition to restore it.
I think he is actually accomplishing zero torque up front, and the hydraulic pressure signal to the clutch is being dumped back into the transmission pan instead of going to the center diff clutch. Further, there IS a return spring assembly in the clutch pack to push the piston away and allow the clutches to open fully.
FTM:
Hydraulic Control (Line Pressure Control)
(1) Line pressure for transmission control is also used by the transfer to simplify the transfer hydraulic system.
(2) Line pressure from the transmission is controlled by a modulator valve so that it does not rise above a specific level. This stabilizes hydraulic control of the transfer control solenoid assembly.
(3) Hydraulic pressure controlled by the transfer control solenoid assembly operates the control valve. The pressure also controls the slip status of the center differential limiting clutch by modulating the line pressure from the transmission in the transfer control solenoid assembly.
Transfer Control Solenoid Assembly
(1) The transfer control solenoid assembly is integrated with the electromagnetic section and the pressure modulating section. The spool pushes the pressure modulating valve in accordance with the electric current value that makes the electromagnetic section function. The pressure modulating valve then generates hydraulic pressure to resist the pushing force of the spool, thus making it possible to obtain hydraulic pressure proportional to the electric current value.
FAIL-SAFE
(a) The fail-safe function minimizes the loss of operability when an abnormality occurs in a sensor or a solenoid.
(b) For details, refer to the Repair Manual. (<- the manual doesn't explain much besides what I note below)
He can prove this by putting his car on some jack stands or a lift and putting it in gear. The fronts might slowly turn, but they're not going to match the rears at all if fourgs is right. Also, since he has a plethora of white stuff outside, he should just be able to get his car into AWD-off with TRAC and VSC off and be able to do a "burnout" with just the rears in a straight line. He should also be able to do some donuts easily. It looked like he couldn've in his video.
I wonder, with any car fully off then the front drivetrain would typically be free to spin, no? Two people should be able to grab the front tires and turn both the same direction freely with no hydraulic pressure to the clutch pack. If this is true, then this means it would be possible to disable the front end completely on a whim. You'd just need to cycle the ignition to restore it.
If the fronts turn at all, you are getting partial clutch engagement and the possibility of increased wear/reduced life. This knowledge would allow the community to best determine whether that is an acceptable risk to take with their own cars.
Intermediate
Joined: Jul 2022
Posts: 407
Likes: 126
From: North Carolina
This is all I was saying. Test, don't assume that the clutches are released.
If the fronts turn at all, you are getting partial clutch engagement and the possibility of increased wear/reduced life. This knowledge would allow the community to best determine whether that is an acceptable risk to take with their own cars.
If the fronts turn at all, you are getting partial clutch engagement and the possibility of increased wear/reduced life. This knowledge would allow the community to best determine whether that is an acceptable risk to take with their own cars.
So then here's another caveat: hold both front wheels while the system is disabled and then shift the car to D. The wheels should stay still (the people holding them may feel something though). Then slightly press the gas, and they should be able to hold them still, although whomever is holding the wheels will likely still feel something wanting to move the tire a little. That's 0.6mm-ish clearance, Between the clutches that's still .06mm of fluid between each friction and clutch. They're going to impart some force to the front, but it definitely won't be a lot. It'll drag through the fluid if the front wheels are stopped.
Not sure if I'd drive it much like that, this is a big unknown.
Thread Starter
Pit Crew
Joined: Feb 2022
Posts: 244
Likes: 66
From: IL
I wouldn’t regularly drive like that also. Techstream works slow I would loose 15 minutes every time to turn it off and for what reason. There are no benefits in turning it off. Even fuel economy doesn’t change since drive shafts are still there rotating passively. I did it just for fun to play in the snow in rwd mode. And then happily swiched to awd to play some more because is doesnt oversteer in awd mode.
They may turn some, as it is a wet clutch. Even some automatic trannies will transfer just a slight amount of force through the fluid when dissengaged. Not as effective as a torque converter turbine, but enough to be noticed.
So then here's another caveat: hold both front wheels while the system is disabled and then shift the car to D. The wheels should stay still (the people holding them may feel something though). Then slightly press the gas, and they should be able to hold them still, although whomever is holding the wheels will likely still feel something wanting to move the tire a little. That's 0.6mm-ish clearance, Between the clutches that's still .06mm of fluid between each friction and clutch. They're going to impart some force to the front, but it definitely won't be a lot. It'll drag through the fluid if the front wheels are stopped.
Not sure if I'd drive it much like that, this is a big unknown.
So then here's another caveat: hold both front wheels while the system is disabled and then shift the car to D. The wheels should stay still (the people holding them may feel something though). Then slightly press the gas, and they should be able to hold them still, although whomever is holding the wheels will likely still feel something wanting to move the tire a little. That's 0.6mm-ish clearance, Between the clutches that's still .06mm of fluid between each friction and clutch. They're going to impart some force to the front, but it definitely won't be a lot. It'll drag through the fluid if the front wheels are stopped.
Not sure if I'd drive it much like that, this is a big unknown.
Intermediate
Joined: Jul 2022
Posts: 407
Likes: 126
From: North Carolina
It'd be pretty neat if the bore had enough travel and we could get rid of a friction and disc to get some more clearance so it could function more like a RWD to AWD engagement. Then again, I'm sure the engineer's math for the case and other components didn't account for ingenuity...
This is one of those moments I wish I'd won the lottery so I could do some R&D about these things myself.
Anywho, I just tried that pedal dance trick on my car several times, and I think the key to making it work is to make sure the parking brake fully disengages and re-engages (the PARK light needs to go off and on after you've pressed/pulled on the switch). Then it'll work. Just did it a few times in my driveway to make sure that's the key.
Fourgs, does the car still start in 2nd even with the handling system disabled if you're in the snow or is it going to 1st gear like normal?
This is one of those moments I wish I'd won the lottery so I could do some R&D about these things myself.
Anywho, I just tried that pedal dance trick on my car several times, and I think the key to making it work is to make sure the parking brake fully disengages and re-engages (the PARK light needs to go off and on after you've pressed/pulled on the switch). Then it'll work. Just did it a few times in my driveway to make sure that's the key.
Fourgs, does the car still start in 2nd even with the handling system disabled if you're in the snow or is it going to 1st gear like normal?
It'd be pretty neat if the bore had enough travel and we could get rid of a friction and disc to get some more clearance so it could function more like a RWD to AWD engagement. Then again, I'm sure the engineer's math for the case and other components didn't account for ingenuity...
This is one of those moments I wish I'd won the lottery so I could do some R&D about these things myself.
Anywho, I just tried that pedal dance trick on my car several times, and I think the key to making it work is to make sure the parking brake fully disengages and re-engages (the PARK light needs to go off and on after you've pressed/pulled on the switch). Then it'll work. Just did it a few times in my driveway to make sure that's the key.
Fourgs, does the car still start in 2nd even with the handling system disabled if you're in the snow or is it going to 1st gear like normal?
This is one of those moments I wish I'd won the lottery so I could do some R&D about these things myself.
Anywho, I just tried that pedal dance trick on my car several times, and I think the key to making it work is to make sure the parking brake fully disengages and re-engages (the PARK light needs to go off and on after you've pressed/pulled on the switch). Then it'll work. Just did it a few times in my driveway to make sure that's the key.
Fourgs, does the car still start in 2nd even with the handling system disabled if you're in the snow or is it going to 1st gear like normal?
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