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just put a deposit down on an STi

Ok, I've been trying to figure out how to use the DCCD and just driving around doesn't really give me any insight. Can someone explain it to me? I have no idea what people mean when they talk about locking it and whatnot. Also, why, at low speeds, when in the manual position does it sound like it is tearing the drivetrain out? Anyone that can give me an answer, thanks.
 

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From reading the threads on this topic and being inexperienced, I've concluded that leaving it in auto , except in snow, then maybe locked at 50/50 is best for those not racing off road...?
 

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I would choose 0% lock (35/65) when driving on dry freeways, and partial lock (from position 3 up to one before lock) for the twisties, and full lock (50/50) when it rains and snows ...
 

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that's not 0%lock or 100%lock, it's locked, and that's how much of the drive is going front/rear in %. if you have it switched to auto, the computer is constantly adjusting the % frt/rr, if you switch it to locked, you control the split. auto makes the car as close to idiot proof as it can be, locked @ 50/50 adds some fun, and as you roll it back, the fun factor increases...
the noise you hear is normal, it's because the diff is locked and the front wheels are traveling a longer distance that the rears when you make a sharp turn.
 

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The DCCD wheel controls the degree of lock in the center differential, not the torque split, and least not directly.

In the Open position, the center differential becomes an open differential, not a limited slip differential. Obviously, in this position, either the front tires or the rear tires can spin. In the Open position the torque split is always 35% front/65% rear.

In the Lock position, the center differential becomes fully limited slip: the differential will not send torque to wheels that are spinning. The torque split under full traction is about 50/50. If either the front or rear wheels have lower traction, the torque split will favor the end with traction.

Think of the DCCD as a clutch between the front and rear driveshafts. In Open, the clutch is engaged and the driveshafts are independent. With the clutch released, the shafts are locked together with as much force as the clutch can provide. With the DCCD somewhere in between Open and Lock, the amount of binding force between the driveshafts is varied.

See the DCCD FAQ for more information:

http://wallace.as.arizona.edu/~cgroppi/DCCD_FAQ/DCCD_FAQ.html

Read it a couple times carefully...I learn something new each time I read it.
 
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