[felonious]

Ah, the dreaded DCCD discussion!!

Okay, so we all know what DCCD is (hopefully), with some of us even having that as a purchase consideration! But how many of us know how to effectively use it in manual mode?

This thread is for real-world examples of where you've successfully used the DCCD manual setting - what you were doing, what it was set to, and why you liked it.

I'll start.

In autocross, I've found that putting the DCCD on the bottom yellow (where the white line on the dial is exactly in top-dead-center) works really well. I believe this translates to a roughly 40-60 front-rear distribution.

I used to be religious about full-auto mode, but one day I had some extra runs and tried different settings. The first setting I tried was full rear. While this is fun for daily driving (getting the tail out easier), I found it was a little too tail-happy for autocross. I then tried one up from full rear. It was better, but still not good enough. On my next run, I did two up from rear, which is what I'm recommending here. It was still slightly tail-happy, allowing for throttle-on rotation, but it was extremely controllable. When sliding, I would drift almost sideways with the tail coming around very slowly. I'm really happy with this setting and will be using it from now on.

-Ollie

[sciolist]

My initial thought was that manual would be better for autoX, but my times are better in automatic. My theory was that the car’s behavior would be more predictable and “conventional” in a rearward manual setting, but my experience has been that it’s not hard to learn how to use it effectively in auto. My approach has been to modify the suspension for neutrality and rotation and stick with the auto DCCD.

From a practical standpoint, I use the lock setting for loose surfaces and auto for most other situations.

I will continue to experiment with manual setting for racing, but auto seems like more of an asset than a liability to me.

[Xman]

I stick with full auto and have become familiar enough with the algorithims that the car no longer surprises me. I guess I have turned myself over to the machine and let it do the thinking for me and I just put the car where I want it and let the magic happen. I tried the manual settings and they were definitely more predictable, but the extra half tenth or so that the auto setting gets me on corner exits has me sold. For most people I would recommend working with the manual setting until they know exactly what the car will do in every situation, then switch it into auto and start learning all over again and pick up a few more fractions. If you aren't that ultra competitive, leave it in manual and have loads of fun.

Daily driving I leave it in Auto. the only time I put it in lock is for messing around in loose surfaces or trying to make different shaped donuts :O

[JKonquer]

using manual dccd mode, is this bad for the car?
i notice that if you put the dccd setting on all the way rear, the differential makes clinking sound, the manual says its normal, but is it ok to drive everyday with manual mode?

[felonious]

I drive in manual mode a lot, just not when making tight turns.

-Ollie

[sciolist]

Originally Posted by JKonquer

using manual dccd mode, is this bad for the car?
i notice that if you put the dccd setting on all the way rear, the differential makes clinking sound, the manual says its normal, but is it ok to drive everyday with manual mode?

It’s fine if you can break traction – that’s what the DCCD is for. Just toggle back to AUTO when you come back to the grid or pit. Or, if you’re driving on the street, toggle back when you slow down and pull into a parking lot, or some other situation where you’ll be making tight turns with full traction.

So I've gathered that my leaving it in lock for extended periods due to poor weather will not cause any harm... anything I should know about leaving it in lock?

[Pyrex]

Originally Posted by BOOST

So I've gathered that my leaving it in lock for extended periods due to poor weather will not cause any harm... anything I should know about leaving it in lock?

Don't use lock on paved roads unless it is really slippery (ice, snow). The other settings are supposed to be fine for daily use (although I wouldn't have it too close to lock when making tight turns on pavement). Leaving it on open (green box, dial all the way back) is fine for driving on pavement.

[jays05]

Every time I have heard of somebody breaking their rear axles, they were at the dragstrip (launching hard) with the DCCD in manual/full open. Having the DCCD in auto seems to be a lot safer for hard launches.

[MeoW71]

I've run my STi on snow with it in manual/full open. Rear end wanted to break away like crazy if you stepped on it. Of course, this is not the recommended setting. I was bored and wanted to try stuff out.

[felonious]

Some interesting results from this last autocross session... I was running my usual two-up-from-rear and got two runs in - 74.956 and 74.414. For my last run, I decided to try out what had been suggested here, and went with full auto. That got me a 73.101! Now, normally I'd say I just improved my driving, but considering my first two runs were that consistent, I'd say at least some of the credit for taking 1.3 seconds off my time goes to the automatic center diff doing its job!

It was a very enlightening experience.

-Ollie

[jim]

That sounds like my experience. DCCD manual feels faster to me, but my times are almost always better with it in AUTO.

[WRX_Mundi]

I've tested it on and off at autocrosses and at a hillclimb. When I got the car I left it in auto for the first 100 or so runs (I went to three days of Evolution school which is a lot of runs). For a number of autocrosses at the end of 2003 and the beginning of 2004 I tried different settings ranging from full open to one down from full lock. On some settings and some lots I thought manual felt better. On some I thought it felt worse. On every occasion, auto was slightly faster. I no longer play with it and concentrate on my driving.

I imagine there is some rain point where a manual setting would be better, but I haven't had a good chance to find out. My experience so far is that sprinkling + R compounds + Subie AWD = crushed competition, regardless of DCCD setting. In 54 events with the STi I've not yet had one that rained all day, but a few with wet halves. I need to get out to the northwest...

I've driven and autocrossed some RWD cars, and no manual setting makes the car feel remotely like a RWD car to me. The front wheels are always pulling no matter what the DCCD is set to.

Full lock or close to it is great in the snow. Better than auto, at least for daily driving. With all-seasons and full lock it's easy to go when the SUVs and trucks with their big tires are spinning in place. Stopping is another matter... All seasons plus ice is no fun at all.

[305Black05Sti]

Is it bad to mess with it while driving, and not at a stop?

[Digitalfiend]

Originally Posted by 305Black05Sti

Is it bad to mess with it while driving, and not at a stop?

You can change it on the fly, no problem. The centre differential is electromagnetically controlled so there is nothing to worry about.