Nah the power distribution is static, but the torque can be limited to certain wheels depending on slip.

For example, let's say you've got 100ft lbs of torque in total and the impreza is running 65:35 rear:front.

That means rear wheels get 65ft lbs and front get 35.

Now let's say fronts are on ice, and only need 7ft lbs before slipping. The centre diff will then limit the front to 7ft lbs but the ratio must stay the same, so the back then gets only 15ft lbs to maintain 65:35

If set to lock, the torque is fixed so all 100ft lbs will be used regardless of slip.

My maths are probably wrong, but that's my understanding of it and I'd love someone to correct me.

In auto, the open/lock relationship is constantly being adjusted on the fly so is better for 99% of driving.

 

Ahhhh right I see yeah your maths is ok there (divided each side by 5) to get the figures of 7 and 15.

Thats a good explanation Fonzey.

How do you drive yours?

 

The only time my DCCD has been used, was when I had my 5 year old son sitting in the front, and I pulled off from the petrol station after paying(left him in the car) and I could feel the wheels locked as I pulled away.

I just keep it in Auto, at least I understand that bit!!!

 

Yep the divide by 5 thing was arbitrary, but made the point that limited traction on one axle would reduce the torque on the other one to maintain the torque split proportion.

I drive in auto on track and as a daily, only ever used lock in the snow for getting off my drive, then back into auto once moving.

When hooning, I can feel the car dragging me through a corner via the transmission so the auto is definitely working for me.