DCCD FAQ

JJ · 12-19-2004, 11:19 AM

The DCCD (Drivers Center Controlled Differential) is probably one of the most interesting and advanced parts of the STi, and yet one of the most misunderstood.

Here's some excellent useful info on the DCCD:

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

**Digitalfiend** · 12-22-2004, 08:43 AM

Just to add some more information:

Everyday driving:

While buzzing around town and general everyday driving, it is generally agreed that the DCCD should be set to Auto. This provides a default of 35/65 which balances to 50/50 under hard acceleration.

Drag strip:

A lot of people find that Auto works the best on the drag strip. People seem to cut more consistent 60' times. This doesn't mean Open (35/65) doesn't work, but for the most part people have had great success in Auto.

Clunking/Shuddering While Parking:

If you hear and/or feel some serious clunking, grinding, or shaking, while making tight turns and/or parking, it is most likely due to the fact that you don't have the DCCD set to Auto. When you use one of the Lock modes, you are trying to force the wheels to turn at the same rate which causes much grief to the differentials. No one knows if this can actually cause damage but from how it sounds, I wouldn't want to risk it.

Therefore, for parking or tight turns use Auto.

When Should I Use Lock?:

The lock-modes should be reserved for when traction is very limited. A good example would be icy or snow covered roads/parking lots. Another good example would be loose surfaces such as heavy gravel etc. Auto mode will still work in these situations but under certain conditions, lock will definitely be better.

**TRM** · 03-19-2005, 04:17 AM

i mirrored this DCCD write up on my server. i know how these files, when located on educational servers, can mysteriously just disappear without notice.

DCCD FAQ by Seth Cooper - Mirror

cruzSTI · 04-03-2005, 08:13 AM

Quote:

Originally Posted by JJ

Here's some excellent useful info on the DCCD:

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

I've got to say that I find this "FAQ" actually quite useless. Not that anything in this paper is really wrong or misleading, it's just not very useful information for the average enthusiast or racer. It reads like an undergraduate paper written for an engineering tech writing class. Nothing wrong with that per se, but it's disheartening to see this posted all over this site and NASIOC as the holy grail of figuring out how to properly setup the DCCD for various situations.

Many of us know the principals of the various components of the DCCD system -- it's the interplay between them and the mapping of the settings to various driving situations that is missing from the Subaru-provided information.

I've found lots of good stuff on DCCD at www.scoobynet.co.uk.

**TRM** · 04-03-2005, 02:10 PM

cruz, it's a technical article on how the DCCD works. what i think you might be after is a "how to set" the DCCD based on driving and road/track conditions.

***gixxer6*** · 04-03-2005, 02:58 PM

i'd like to see something that tells what the power split is in each setting, i've never seen anyone post that before unless i've missed a post somewhere.

cannyboy · 04-04-2005, 10:16 AM

I recently got to use the STI for a day on a frozen lake.
While Locking the diffs will produce more stable acceleration, it turns the STI into an understeering pig.

In Auto, the car was much faster when timed over locked. The only downside of the Auto, is that the car is more unstable, but quicker.

So if you are driving down to the shops on a snowy day, Locked is much safer and less stressful to drive with. The car is more predictable, and stays solid on the road.

When pushing on, with room for mistakes, or racing on Ice, stick it in auto and hang on - understeer is much reduced, but you'll be a busy boy at the wheel keeping everying in check........

flytojungho · 04-08-2005, 08:13 AM

can you change the setting of DCCD while driving?

lownotes · 04-08-2005, 08:27 AM

yes. And I believe it's an electronic/magnetic type of system in that there are no physical mechanical direct 'gear' type changes like a manual transmission has. someone will correct me if I'm wrong I'm sure.

pantag · 04-08-2005, 10:19 AM

You can change the DCCD setting on the fly, but make sure none of your wheels is spinning (loosing grip) while you are playing around with DCCD.

jays05 · 04-08-2005, 11:58 AM

Quote:

Originally Posted by gixxer6

i'd like to see something that tells what the power split is in each setting, i've never seen anyone post that before unless i've missed a post somewhere.

jays05 · 04-08-2005, 12:00 PM

No DCCD FAQ thread is complete without these two gems below. Study the funky 3d graph then watch the flash animation (in japanese), you can see why auto is a superior dccd setting for street/track use.

Flash animation

Titleist71 · 04-08-2005, 12:56 PM

Quote:

Originally Posted by flytojungho

can you change the setting of DCCD while driving?

I wouldn't.

Titleist71 · 04-08-2005, 12:58 PM

Quote:

Originally Posted by pantag

You can change the DCCD setting on the fly, but make sure none of your wheels is spinning (loosing grip) while you are playing around with DCCD.

Correct. I would drive around only when the setting is in the GREEN....on dry tar. The settings above the bottom two should only be used for dirt, snow/ice and such. Otherwise stay in Auto.

305Black05Sti · 05-01-2005, 06:58 PM

is it bad to change at 80 for instance on the highway 2 the complete bottom setting or the rear wheel drive one?

12-19-2004, 11:19 AM	#1
JJ Spec C Club Car: subaru's, other cars, computers, this site Location: Arvada, Co Posts: 1,216 Join Date: Aug 2001 Trader Rating: (0)	RE: Beware NJ The DCCD (Drivers Center Controlled Differential) is probably one of the most interesting and advanced parts of the STi, and yet one of the most misunderstood. Here's some excellent useful info on the DCCD: http://wallace.as.arizona.edu/~cgrop.../DCCD_FAQ.html This ad is not endorsed by this member. Please register or login to hide this ad.

04-08-2005, 12:00 PM	#12
jays05 Spec C Club Fav Mod: when it's not blown up Location: Upstate NY Posts: 1,542 Join Date: Nov 2004 Trader Rating: (0)	No DCCD FAQ thread is complete without these two gems below. Study the funky 3d graph then watch the flash animation (in japanese), you can see why auto is a superior dccd setting for street/track use. Flash animation Last edited by jays05 : 04-08-2005 at 12:06 PM.

05-01-2005, 06:58 PM	#15
305Black05Sti Lurker Posts: 5 Join Date: Apr 2005 Trader Rating: (0)	is it bad to change at 80 for instance on the highway 2 the complete bottom setting or the rear wheel drive one? This ad is not endorsed by this member. Please register or login to hide this ad.

12-22-2004, 08:43 AM	#2
Digitalfiend Super Moderator Car: 08 DGM STI Fav Mod: My wife :) Location: Brooklin, Ontario Posts: 5,319 Join Date: Oct 2003 Trader Rating: (0)	Just to add some more information: Everyday driving: While buzzing around town and general everyday driving, it is generally agreed that the DCCD should be set to Auto. This provides a default of 35/65 which balances to 50/50 under hard acceleration. Drag strip: A lot of people find that Auto works the best on the drag strip. People seem to cut more consistent 60' times. This doesn't mean Open (35/65) doesn't work, but for the most part people have had great success in Auto. Clunking/Shuddering While Parking: If you hear and/or feel some serious clunking, grinding, or shaking, while making tight turns and/or parking, it is most likely due to the fact that you don't have the DCCD set to Auto. When you use one of the Lock modes, you are trying to force the wheels to turn at the same rate which causes much grief to the differentials. No one knows if this can actually cause damage but from how it sounds, I wouldn't want to risk it. Therefore, for parking or tight turns use Auto. When Should I Use Lock?: The lock-modes should be reserved for when traction is very limited. A good example would be icy or snow covered roads/parking lots. Another good example would be loose surfaces such as heavy gravel etc. Auto mode will still work in these situations but under certain conditions, lock will definitely be better.

03-19-2005, 04:17 AM	#3
TRM i am Darwin's rottweiler. Car: 04 STi Fav Mod: Driving Lessons Location: Eastern PA Posts: 2,197 Join Date: Oct 2003 Trader Rating: (0)	i mirrored this DCCD write up on my server. i know how these files, when located on educational servers, can mysteriously just disappear without notice. DCCD FAQ by Seth Cooper - Mirror

04-03-2005, 02:10 PM	#5
TRM i am Darwin's rottweiler. Car: 04 STi Fav Mod: Driving Lessons Location: Eastern PA Posts: 2,197 Join Date: Oct 2003 Trader Rating: (0)	cruz, it's a technical article on how the DCCD works. what i think you might be after is a "how to set" the DCCD based on driving and road/track conditions.

04-03-2005, 02:58 PM	#6
*gixxer6* sponge worthy Location: Mountains of NC Posts: 1,580 Join Date: Oct 2004 Trader Rating: (0)	i'd like to see something that tells what the power split is in each setting, i've never seen anyone post that before unless i've missed a post somewhere.

04-04-2005, 10:16 AM	#7
cannyboy Amateur STI Driver Posts: 44 Join Date: Aug 2004 Trader Rating: (0)	I recently got to use the STI for a day on a frozen lake. While Locking the diffs will produce more stable acceleration, it turns the STI into an understeering pig. In Auto, the car was much faster when timed over locked. The only downside of the Auto, is that the car is more unstable, but quicker. So if you are driving down to the shops on a snowy day, Locked is much safer and less stressful to drive with. The car is more predictable, and stays solid on the road. When pushing on, with room for mistakes, or racing on Ice, stick it in auto and hang on - understeer is much reduced, but you'll be a busy boy at the wheel keeping everying in check........

04-08-2005, 08:13 AM	#8
flytojungho Spec C Club Car: 06 STI Fav Mod: Prodrive oval tip Location: carmel indiana Posts: 1,260 Join Date: Mar 2005 Trader Rating: (0)	can you change the setting of DCCD while driving?

04-08-2005, 08:27 AM	#9
lownotes Junior STI Driver Location: Pittsburgh Pa Posts: 123 Join Date: Jan 2005 Trader Rating: (0)	yes. And I believe it's an electronic/magnetic type of system in that there are no physical mechanical direct 'gear' type changes like a manual transmission has. someone will correct me if I'm wrong I'm sure.

04-08-2005, 10:19 AM	#10
pantag Spec C Club Car: 06 Subaru WRX STi Fav Mod: My right foot... Location: Waterford CT Posts: 1,996 Join Date: Nov 2004 Trader Rating: (1)	You can change the DCCD setting on the fly, but make sure none of your wheels is spinning (loosing grip) while you are playing around with DCCD.