tcu to duty solenoid mod?

[patb3]

Hello,

I read a FAQ that SoCal-LS-L made (it was in his signature) about a tcu to duty solenoid mod. I tried searching for more info on it here but couldn't find any. Hoping someone knows more about this. Here is the excerpt from the FAQ:

"For firmer shifts, you could also do the same thing from the TCU to 'duty control solenoid' A to remove the signal. This would force full line pressure into up shifts. For 4-wheel drive 'lockup', you can disable (switch off) duty solenoid 'C', this will lock the car in 4 WD (50/50). You could probably wire all of these circuits into a single switch (say under the accelerator pedal, or tied to the 'Manual switch"). This would be great for racing."

I am mostly interested in this for manually setting the diff to 50/50 (I live in Maine with bunches of snow). Thanks!

[Freeman]

You do know that with AWD, your vehicle will automatically shift to 50/50 when and if you start to slip, right?

[patb3]

I wasn't quite sure, actually. One night it snowed really good here and my friend tried to move my car for me (by putting it into D), and the front tires just spun with the car going no where. I come outside and put it into 1, and was able to pull out with ease. Is there a difference in the differential when it's in D rather than 1, 2, or 3?

[redlightningsvx]

The Power mode mod doesn't do anything for drag racing.

[log1call]

Putting it in 1st does increase the drive ratio to the rear wheels. It makes it "more aggressive" according to subaru. But, there should be drive there in any gear. As someone else suggested earlier, if slip is detected the trans ecu will decrease the duty cycle so the rear wheels drive more.

[SoCal LS-L]

Originally Posted by patb3

Hello,

I read a FAQ that SoCal-LS-L made (it was in his signature) about a tcu to duty solenoid mod.

Oh I didnt make that I happened across it while mashing my keyboard in a drunken stupor....... My FAQ is mostly about breaking things on the way to my timing belt.

[1986nate]

in "1" and "2" the transmission splits power 50/50 but the front can still spin since it is an open differential in front.
The 50/50 AWD All time mod is not a good idea even for the snow, not only do you get much worse gas mileage, but it also puts a lot more stress on the transmission.

[Freeman]

If only your front wheels are spinning and back ones aren't, especially when your slipping, you may have something fairly wrong with your transmission...

[oab_au]

Originally Posted by patb3

Hello,

I read a FAQ that SoCal-LS-L made (it was in his signature) about a tcu to duty solenoid mod. I tried searching for more info on it here but couldn't find any. Hoping someone knows more about this. Here is the excerpt from the FAQ:

"For firmer shifts, you could also do the same thing from the TCU to 'duty control solenoid' A to remove the signal. This would force full line pressure into up shifts. For 4-wheel drive 'lockup', you can disable (switch off) duty solenoid 'C', this will lock the car in 4 WD (50/50). You could probably wire all of these circuits into a single switch (say under the accelerator pedal, or tied to the 'Manual switch"). This would be great for racing."

I am mostly interested in this for manually setting the diff to 50/50 (I live in Maine with bunches of snow). Thanks!

That FAQ was written some time ago. A lot of information has been leaned since then.
Turning the A solenoid off is not the best way to do it, it produces a number of other problems. The best way to help the gear shifting is to fit a Quick Change.

http://www.subaru-svx.net/forum/showthread.php?t=45197

Locking the C solenoid should only be done when running the 1/4 mile.

Harvey.

[patb3]

thanks for the opinions guys