Ste.. I don't think he'll mind some cutting a pasting from his original thread, but this is straight from an excellent John Felstead response to a similar DCCD question in October 2002. I was sent a more technical link to a recent DCCD-A .pdf, but the link's not working.. I'll post it here in case it comes back..

I don't think there's too much difference between the earlier and later versions, only that the MY05 and later has a Yaw sensor

http://www.phear7imports.net/tech/07...l%20System.pdf

Happy reading..







And his text:

asked a guy i know who lives in Japan to have the owners manual translated for me in respect to the STi TypeR/RA DCCD Centre diff controller as i felt the information in the owners manuals i had read did not give a clear indication of how it should be used, i also noticed some sections of the translated manual were missing.

It took about a week to get done, this is the result. Yes you can drive on tarmac using the diff, including using full lock! Yes you will get some vibration if you run with the display in the orange range, that is normal and is not causing damage to the diff. You can get vibrtion and shock loadings under heavy braking due to variations in front/rear rotational rates, that is normal. You will get transmition wind up in slow manouvers when the diff is in the orange, you can cancel this out by just lifting the handbrake until the handbrake light illuminates. The reason the display has orange/green colours is to indicate at what point you will start to get some posible shuddering in slow manouvers. Also the diff is not a six way position, its infinately adjustable using a potentiometer with 2 switched ends.

Below is the translation.

DRIVER'S CONTROL CENTER DIFF
(SKETCH5046)
(SKETCH5852)
The intent of this mechanism is to adjust the diff lock ratio of the LSD (limited slip differential) as necessary.
Adjusting the dial to "diff free" (indicator: green, empty square, empty triangle) under normal driving conditions, and "diff lock" (bright orange solid triangle) on gravel, snow, in the rain, is effective (probably means suggested). By setting the diff lock ratio as necessary, depending on the various roads and running conditions, unrivaled driving mobility will be demonstrated.

WARNING!
This is not an all purpose vehicle. DO NOT overestimate its abilities. Please use appropriate discretion and drive at safe speeds where there are sudden braking, sudden turns, sudden curbs, snowy roads, slippery roads, etc.

USING THE CONTROL DIAL
(SKETCH5048)
The dial is located next to the handbrake lever, rotating it fully forward is diff free, rotating it fully backward is diff lock. You can continuously change the diff lock ratio using the settings in between.
DIFF FREE: No front and rear LSD (Front to rear power distribution=36:64)
DIFF LOCK: The front and rear have an almost direct connection. (Front to rear power distribution=front/rear load distribution)
(CHART1)

INDICATOR (ON THE METER DISPLAY)
The diff lock ratio is displayed at one of six settings, as it is linked to the control dial. The upper lighted block (orange solid triangle) indicates a greater direct connection.
The true lock ratio can be continuously changed.

ADVICE
• The indicator is the criterion.
• Regardless of what the dial settings are, LOCK will illuminate for one second after the key is turned to the on position.
• At night, while your driving lights are on, the display may appear to go dark for a moment, but this is normal.


CANCELLATION OF DIFFLOCK
Even if the DCCD is set to LOCK (orange), by pulling the hand brake lever, it will automatically go to DIFF FREE, moving all power to the rear wheels. (linked to the brake warning light) However, the indicator will not change.
Once you release the hand brake lever, the DCCD will return to its proper setting.

TIGHT CORNER BRAKING PHENOMENON (makes more sense once you read the following)
When the indicator is orange while driving on dry tarmac/asphalt, corners, and even reverse parking, due to the rotational difference between the front and rear wheels, there are cases where heavy vibration and noise may occur during braking.
Though this is not out of the ordinary, and to resolve this "problem", you can simply either set the DCCD to DIFF FREE or pull the hand brake enough so that the brake warning light illuminates.
While you may feel a light "shock" when using the control dial during quick acceleration and tight cornering, due to the movement of the center diff, this is normal.

WARNING!
• DO NOT use the DCCD while any of the wheels are in mid air.
• Set the DCCD to DIFF FREE while the car is stopped.
• Set the DCCD to DIFF FREE while the car is being pulled or towed. The car can only be towed/pulled either by rope or on a rollback. DO NOT pull or tow the car on only its front or rear wheels. Please see page 195 for more information on warnings related to towing.
• ALWAYS set the DCCD to DIFF FREE when using the emergency spare tire. Change or fix the tire as soon as possible.
• When the center diff requires repair (control unit, disconnected wires, shorted wires, voltage issues, etc.) the DCCD reverts back to DIFF FREE and the indicator (at which you last had it set) should flash at 1 second intervals. Please go to your nearest Subaru dealer immediately. Once a problem arises, even if the unit regains power, it will not reset itself until the engine key is set to the off position.


[Edited by johnfelstead - 2/5/2003 1:53:51 PM]

 

On a personal note...

I find that knocking it on to the second green light up has a profound effect on wet roundabouts and corners...

Coming out of tightish corner in auto is definitely a rear wheel bias that has had the back end stepping out on me.. The front is relatively light and the car feels 'loaded' at the back with the steering feeling less positive..

Knocking it out or auto to this setting has the effect of simply nailing the car down.. You can feel the car tighten up.. The steering gets a little heavier and has more feel and any input has a really 'positive' feel. The car's attitude is far more flatter and breaking traction requires some extreme boot.. You're more likely to drift it at this point and I simply don't get any understeer.. Just very positive four wheel drifting...and handling that rightly put this car on the top of the podium at the Tuner GP.

I've yet to play significantly on the other settings in some Ice & snow, but I'd say it's really only useful in wet or slippy conditions..

One otherthing that get's mentioned a lot is the stability of the braking with some lock dialed in.. JF mentiones that he drives with some lock on wet Motorways as in an emergency, the mechanical coupling between the front and back would mean more overall stability under heavy braking.. I'd have to agree that braking does feel 'flatter' and more stable with less dive..

Now, I don't know how much difference you'll find as I'm sure the T20/T25 handling kit (AST's, Fast road geometry, Anti Lift, Uprated ARB's and even the Tyres) will make a massive difference as well.. I also have the JDM Suretrac diff as well.. But taken in isolation, the DCCD-A does make the car's attitude change significantly....

One word of caution...

If you're parking or doing low speed maneuvering, then don't have it in manual on any setting above the second Green as the mechanical noise from the diff & tyres being dragged will have every head turning.. I honestly thought I'd broken the car when pulling into a Domino's Pizza car park in front of a few chavs..

Have a play though..

 

Thanks Al, appreciated.

 

I've yet to play significantly on the other settings in some Ice & snow, but I'd say it's really only useful in wet or slippy conditions..

Mate there is no need for ice and snow it's very dangerous out there at the moment be very cautious