Quote:
Originally Posted by b3lha
I don't think a resistor will do the trick. The solenoid will still pulse open and closed at the same rate.
I think you need a circuit like this to generate your own duty cycle. Then you need a switch to select whether the transmission uses the TCU's duty cycle or the one from your circuit.
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This is correct. The valve is just a normal electronic solenoid, it works like any other on/off valve, only the signal turning it on and off happens very quickly, allowing it to modulate line pressure to the transfer clutch. The pulse width and/or frequency is what allows it to vary the pressure. One would think that a resistor would, in a sense, depress the wave pattern sent out by the TCU (i.e instead of cycling from 0-12v it would cycle from 0-6 or so) which may or may not cause the valve to only partially open( not in a good way, either, it would be like it didn't move fast enough to the open position before it went back to close). This would almost certainly cause rapid failure. As for the effect on actual transfer pressure... I think it would have either no effect (if the valve is still able to fully open) or an effect of making the torque split even less (the more time the valve spends closed, the less fluid pressure the clutch gets).
I am, and have been for years, waiting in eager anticipation for someone to crack the TCU and then we can really start to have fun. I think that a combination of revising the map for the duty c solenoid and shift map will make the car really come alive. The only problem I worry about with modifications to the transfer map like is increased clutch wear if we increase the rear bias too much. I hypothesize that this is why it is conservative from the factory. With Subaru's overall goal of preventing wheel spin from occurring in the first place, it makes sense that they would want as even of a torque split as possible, all other things being equal.
The difference in the JDM and other versions is that it has the Variable Torque Distribution (VTD) type transfer system that includes a mechanical planetary center diff that defaults the torque split to the 35-65. The US SVX would have had this system (it was introduced to the world on the SVX) but at the time the government required that the vehicle be able to operate in 2WD for emissions testing which is not possible with the VTD system. This VTD system didn't come our way until the outback VTD of only a few years back.