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Old 03-01-2005, 02:04 AM   #1
WRX-pilot
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Default DCCD Care, anything to be careful of?

I had a few questions that might be simple to answer. I have searched but get mixed results or unconfident answers. I asked in the Tranny forum but didn't get any responses, I really just want to know how careful you STi guys are with the DCCD.

-When I bought the car, the dealer told me to always keep it in "Auto" mode which is reasonable. But they gave me the impression that it was bad to drive around in manual mode (for lengthen durations) and severly worse if the diff is locked. I could understand it being better to drive with an open diff. However, I was wondering:
a. Are their limits as to how fast you should drive in manual mode... locked or unlocked?
b. Should you not drive around in manual mode (locked or unlocked) for a certain durations of time? If so how long?

-My second concern was changing the DCCD settings. If flipping from Auto to manual and back and changing settings between lock to unlock should I be at a complete stop? Can I change things while in motion? I would imagine this not being an issue since the car itself will automatically change settings in "Auto" mode but I wanted to make sure I am not interfering with anything or straining any part of the car. The owner's manual only stated that settings should not be changed during wheel slippage and to wait until slippage stops, nothing more.

I don't know if asking these questions are dumb, but I'd rather be dumb than sorry. If my questions have already been covered, I apologize, show me where and I'll take the beating I searched for a DCCD faq and only came up with this and did not find my questions answered in there. I consulted the owner's manual but didn't find anything contrary nor complimenting what the dealer said. I am a little skeptical as to what the dealer says versus what SOA itself would be warning me about. Thanks!
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Old 03-01-2005, 03:49 AM   #2
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All I can say is do NOT drive in locked mode unless you are in serious mud or snow.
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Old 03-01-2005, 04:08 AM   #3
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I'm guessing too long and it will fry the differential? I know a guy who does his rally-x's in locked but I have no idea what effects that will have on the car.
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Old 03-01-2005, 05:08 AM   #4
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It is there to use. I really doubt that you will hurt anything if you drive around with it in any setting. In auto it is using the LSD, but I believe in the lock it acts as an open diff. You can change settings on the fly also. You will not break anything just messing with it. The car drives differently in each setting so have fun with it. Also don't get affraid if your car makes weird clunking noises with some DCCD setting. Everyone's STi does that, and it is just normal.
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Old 03-01-2005, 05:26 AM   #5
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yea have fun i like setting mine 35/65 mode.
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Old 03-01-2005, 09:28 AM   #6
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Last edited by big_mac314; 03-01-2005 at 11:58 AM.
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Old 03-01-2005, 10:30 AM   #7
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its a better idea to use locked mode ie 50/50 distrubution only on slippery surfaces or if your drag racing in a straight line. Putting the DCCD in Locked means your center diff is locked together and therefore your rear wheels and front wheels always turn at the same speed. This is good for traction but not for turning when you need the wheels to turn independently.
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Old 03-01-2005, 10:31 AM   #8
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Good advice here. Check also in your Owners Manual as it might provide you with some information as to what Subaru thinks.
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Old 03-01-2005, 11:31 AM   #9
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Right- Left independance is more important than Front - Rear for turning, unless you are trying to drift.
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Old 03-01-2005, 12:25 PM   #10
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don't change it while you're driving... so i've heard
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Old 03-01-2005, 12:45 PM   #11
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Quote:
Originally Posted by 337drew
don't change it while you're driving... so i've heard
Actually you can, so I've heard..I got 13,000 miles on my STi and when I play in the snow, I switch while on the fly. No problems and no noises that most people get with thier diffs.
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Old 03-01-2005, 02:38 PM   #12
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Auto mode make sense for most situations and there is no reason to change it out of that in normal driving. (Some have reported better fuel economy driving in manual mode, though)
No limits on driving speed in manual mode.
You can drive in manual mode all day if you want. The only time you should avoid it is drving at anything less than full rear in manual mode at low speeds while making sharp turns on dry pavement (think parking lot) as that causes binding and extra stress.
It is fine to change the settings on the fly, though as others said, you shouldn't do it while you are breaking traction as it causes unnecesary strain on the center diff. It probably fine in snow though, as traction is reduced and as such, the DCCD doesn't reach the same stress levels as it does on dry pavement.
The only time you should be fully locked is in very low traction situations like heavy mud and snow.


Personally, I drive everywhere in auto except snow where I have found that manual mode and about 1/2 lock (middle triangle) provided superior traction compared to auto mode. Other than that, I only switch to rear manual mode when I wanna have a little fun on wet pavement.
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Old 03-02-2005, 05:24 AM   #13
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^^Good info, thanks guys. I'll have to take a look at that link big_mac posted. I started playing with it a little today but nothing much really.
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Old 04-07-2005, 02:04 PM   #14
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There was some speak of only using the lock function of the DCCD when driving in a straight line. Is this beacuse the power is forced 50-50 in the front and rear regardless of traction? is it a good idea to use this on gravel? Would someone want to use the lock function during a rally-x event?
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Old 04-07-2005, 02:29 PM   #15
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The lock mode is really the same thing as 4x4 drive. As such, you really should only use it on surfaces where wheel slip is possible and expected. I think if you visit the Subaru AWD website and read under the DCCD it explains this in more detail. You can drive in manual mode (excluding locked) at any speed and in any condition. That is what it is for.

One thing I don't quite understand is is there only one "locked" bias? Basically you have two modes, auto and manual. Auto maintains a 35/65 front/rear bias under normal conditions but changes as needed. Now switch to manual. The top option is manual locked, which is 50/50 front/rear bias without the ability to change as needed. Right? Now when you adjust the wheel to move down from the locked bias, does those additional options of bias remain locked or do they maintain a specific bias under normal conditions but have the ability to change as needed a la the auto mode? That part has always been unclear to me.

Last edited by conker69; 04-07-2005 at 02:45 PM.
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Old 04-07-2005, 03:33 PM   #16
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See! It is a tough question.
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Old 04-08-2005, 03:39 AM   #17
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Yeah, I see what you are saying. Unfortunately the DCCD FAQ doesn't have the exact answer from what I read. All of the examples do not mention the answer you seek but I would think that they would have brought it up if that was in fact the case. I would put money on it being locked at whichever setting you selected and it would only automatically go 35/65 in auto mode.
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Old 04-08-2005, 07:42 AM   #18
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Thanks for the link! I guess I will just have to check myself this weekend. Being very familar with 4x4 (locked) all I have to do is go to a gravel parking lot and lock the DCCD and turn in a tight circle. You should have wheel spin from the right rear wheel assuming a counter-clockwise turn if it is truely locked. Then I will try the other setting to see if they are locked or not.

Funny thing is Subaru's AWD website doesn't go into any real detail either.
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Old 04-08-2005, 11:19 AM   #19
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Quote:
Originally Posted by WRX-pilot
Yeah, I see what you are saying. Unfortunately the DCCD FAQ doesn't have the exact answer from what I read. All of the examples do not mention the answer you seek but I would think that they would have brought it up if that was in fact the case. I would put money on it being locked at whichever setting you selected and it would only automatically go 35/65 in auto mode.
It is my belief that the locked mode is only 50/50. The other manual settings just changes the bias(towards rear) i.e. 45/55; 40/60 and 35/65. In auto, it just varies from 50/50 to 35/65 and the CD is not locked.

Locked is not advisable for dry road conditions. You almost never should do this as it will put undue stress to the drivetrain not to mention wear on your tires. This should be used in wet conditions where wheel slippage can occur. I personally like this setting driving on fire roads / dirt roads - fun powersliding thru the corners.

Don't try this but it is up to you: In a dry parking lot, lock the CD and drive the car in a circle. If you live in a cul-de-sac, this would be easy. Listen to all the clicks, clunks and groan. Now tell me if that is good for your car.

I grew up driving 4WD jeeps, trucks with lockers, etc. and saw many broken drivetrains.
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Old 04-09-2005, 10:54 AM   #20
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Quote:
Originally Posted by powerslide23
It is my belief that the locked mode is only 50/50. The other manual settings just changes the bias(towards rear) i.e. 45/55; 40/60 and 35/65. In auto, it just varies from 50/50 to 35/65 and the CD is not locked.
So you're saying you think that if you put it on one of the settings in between lock and open it will continue to stay open at 35/65 and it if it detects slipping it will only lock up to whatever setting you have the DCCD set to?
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Old 04-10-2005, 11:10 AM   #21
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No, I should have explained it better. When 'O' is selected, the CD is open and in this case, the bias is still 35/65 all the time regardless if your tires are spinning / slipping.

Any of the settings between 'O' and 'Locked' sets the different bias front to rear and is a limited slip cental differential i.e. between 50/50 to 35/65.

When locked is selected, it is 50/50 bias and the CD is locked but since it is not really a mechanical locker like a Detroit locker or ARB, it is most likely 99% because it is electromagnet clutch pucks.

Auto is best setting because it selects the appropriate bias depending on the driving conditions and driver demand, etc. That is why most test shows the Auto mode provides the fastest elapsed time.

When in manual or open it stays there regardless if the tires are spinning or not. Just my 2 cents.
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Old 04-10-2005, 01:48 PM   #22
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conker wasn't wondering about auto, locked or open though, we all knew this already. He was asking about the settings in between.
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Old 04-11-2005, 07:53 AM   #23
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I didn't get a chance to go to the gravel parking lot near my house this weekend but I will tonight. I will do some tests and try to get some videos and maybe we can finally get some solid information on the DCCD. At least we should see how "locked" locked really is.

My expectations:

In auto, a 360 circle should not produce any forced wheel slip.

In manual, locked, 50/50, if really locked you will get forced wheel slip.

In manual, anything under the locked option, what I REALLY want to know, is whether or not these setting are locked or just a way to select a different bias while maintaining the auto functionality. Thus, when in a different bias under locked, if locked I should have some forced wheel spin, if not locked, should not have any forced wheel spin.

However, the LSD in the front and rear may create wheel spin regardless depending on how "tight" they are.

Last edited by conker69; 04-11-2005 at 08:07 AM.
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Old 04-11-2005, 12:42 PM   #24
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Just to throw this in, I got about 30mpg driving with the DCCD in O (lowest setting) on the highway. Typically I'll only get ~24mpg on the highway in auto. Take it for what it's worth.
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Old 04-11-2005, 12:48 PM   #25
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Quote:
Originally Posted by BlueDominion
Just to throw this in, I got about 30mpg driving with the DCCD in O (lowest setting) on the highway. Typically I'll only get ~24mpg on the highway in auto. Take it for what it's worth.
Really? The lowest setting is what bias?
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