[hulk252]

A little off topic but OZER your sig is funny as crap!

[lackskill]

Originally Posted by Stargazer

I agree the DCCD doesn't control torque. It controls how much differential lock there is between the wheels. It makes sense to me, maybe because I'm used to off-roading in a 4x4 and having to lock the differentials in low in sticky situations.

My understanding is that when the center differential is locked, the wheels are all spinning at the same speed even when there is no traction. That's why it helps when conditions are slippery. I noticed it this winter when we got a lot more snow than normal. With the system in Auto, the wheels would slip and it would be hard to accelerate quickly and make corners in deep snow. When I locked it, I could accelerate quickly and power drift through corners with total control . I assume it would be the same on loose gravel.

That's the same reason that when there is traction, like dry pavement, the wheels can bind when you're fully locked: The inside wheels turn at the same speed as the outside wheels. That can cause problems so that's why you're not supposed to have it fully locked when you have traction (and want to make turns, that is ).

My snow observations were different than yours. I got major plowing in low traction situations in lock. I suppose this could be attributed to the different f:r ratio on the 06+. For me Auto has been the best setting for all situations I have encountered.

[STiSpeed]

Open FTMFW!

[Ozer]

Hehehe, the funny thing is, my gf found it, who owns an Integra Type-R :P

Originally Posted by hulk252

A little off topic but OZER your sig is funny as crap!

[jays05]

I found the DCCD settings between open and lock to be useful at the dragstrip for dialing in the right amount of wheelspin off the line.

[jays05]

Originally Posted by 06naSTI

I pisses me off that Subaru can't make this simple.

Yeah, maybe they should give us buttons that say Tarmac, Gravel, and Snow instead.

[jungo75]

Originally Posted by jays05

Yeah, maybe they should give us buttons that say Tarmac, Gravel, and Snow instead.

[SWortham]

Originally Posted by stretch

When fully locked, 100% of your torque can go fore or aft. This is not the same as a 50/50 torque split. Instead, you have 100% of the torque going front AND rear to whatever side has the most traction. There is no torque bias anymore since you have a locked differential.

Isn't this all semantics? I mean, Subaru themselves claims in their documentation that the DCCD can shift torque distribution from a 41/59 (open) torque split to 50/50 (locked).

I completely understand what you're saying about the DCCD's primary function of controlling the locking behavior. But to say that torque distribution is not affected is wrong. When the center diff is locked, there is no bias anymore as you said. Effectively, torque will be sent equally to the front and rear wheels (aka 50/50 torque split). The reason is simple -- when the center diff is locked, it's physically impossible for the natural torque bias from the gearing to have any effect.

[stretch]

Right, there is no more torque bias at all. It doesn't have a bias towards anything, nor could it because there is no more center differential. You've essentially converted to a solid (welded) driveshaft. All four wheels (well, at least front and rear driveshafts) will always spin at exactly the same speed. So, the transmission isn't splitting torque at all- the tires are just taking what they need with 100% being available to each one.

To answer the earlier question, you'd only use the manual DCCD in slippery conditions where you didn't want to wait for the computer to react to slip. So snow, dirt, etc. I generally set my diff to 50-75% lock in the snow because that's sufficient enough in slippery conditions to link the front and rear wheels. You do not want to lock the center diff in dry weather, ever, because it creates binding forces in the drivetrain when you turn. That's why some report more understeer or other adverse effects when locked. 2006+ models might be best OK in open since it has that mechanical LSD that is never disabled, but 2004-2005 models I'd recommend leaving in auto.

[mxpop]

After many track day/races, I found that no single setting does as much good for me as auto. It becomes a distraction to mess with it between sections and it can mess you up if you dont get it switched properly and quickly enough.

It's funny how I like to brag to people about being able to control the center diff but in reality, I never touch it.

[supermarkus]

yes, I find that the DCCD controller in Auto is far faster and smarter than I will ever be at controlling the center diff lock up.

[Ozer]

I don't think the statement below is true. The lock only ensures that the tires turn at the same speed. SO, if it is fully locked, but rear tires are on ice while fronts are on tarmac, you will have almost 100% of the torque on the fronts. So it is NOT 50/50. In fact, full lock has nothing to do with 50/50.

- Ozer

Originally Posted by SWortham

Isn't this all semantics? I mean, Subaru themselves claims in their documentation that the DCCD can shift torque distribution from a 41/59 (open) torque split to 50/50 (locked).

I completely understand what you're saying about the DCCD's primary function of controlling the locking behavior. But to say that torque distribution is not affected is wrong. When the center diff is locked, there is no bias anymore as you said. Effectively, torque will be sent equally to the front and rear wheels (aka 50/50 torque split). The reason is simple -- when the center diff is locked, it's physically impossible for the natural torque bias from the gearing to have any effect.

[Stargazer]

Originally Posted by Ozer

SO, if it is fully locked, but rear tires are on ice while fronts are on tarmac, you will have almost 100% of the torque on the fronts.

In that situation, being fully locked means that the front wheels will spin at the same speed as the rear wheels, therefore getting you out of that spot--not really anything to do with moving the torque to the front.

[Stargazer]

Originally Posted by supermarkus

yes, I find that the DCCD controller in Auto is far faster and smarter than I will ever be at controlling the center diff lock up.

That what I hear. But for us regular guys who never get a chance to go out on the track, DCCD is more about maximizing fun than maximizing speed .

[SWortham]

Originally Posted by Ozer

I don't think the statement below is true. The lock only ensures that the tires turn at the same speed. SO, if it is fully locked, but rear tires are on ice while fronts are on tarmac, you will have almost 100% of the torque on the fronts. So it is NOT 50/50. In fact, full lock has nothing to do with 50/50.

- Ozer

I know what you're saying. If you're using the true definition of torque, it comes down to how much grip you have in the front vs rear because it's the greater resistance to rotation that the majority of torque will act upon even though both sets of wheels will be turning at the same speed.

But if you take that same example, even the 41/59 torque split wouldn't truly be a 41/59 torque split. So at what point do you stop trying to classify the dynamics of the torque distribution and just classify its natural tendency assuming equal front & rear grip? I'm calling it 50/50.