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Old 05-17-2014, 01:29 PM   #1
3inchesoflove
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Default STI DCCD setting/differential wear

Just wondering if anyone has an opinion on diff settings that are easiest on the drivetrain.

My first step when I get in the car is to set the diff to the manual full open setting (-) but I am wondering if this causes any excess wear on the parts and if I should stick to the auto - setting.
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Old 05-17-2014, 11:33 PM   #2
niemkij
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I have 90k+ miles on my stock 06 Sti trans. Always use auto setting. No problems.
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Old 05-18-2014, 12:43 AM   #3
mikeydrives1
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Auto is your best bet, hands down.
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Old 05-19-2014, 01:04 AM   #4
Web Foot STi
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Auto is wonderful on the street. Full lock is the worst. Try it some time. The drive train really protests as it binds up. Gravel doesn't hurt anything, but you can hear rocks moving around in tight turns at slow speeds.
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Old 05-19-2014, 07:58 AM   #5
trev762
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The only time u should be worried about wearing or braking drive train parts is launching if u so choose to do so.

If so be in full lock as the power will evenly distributed through out the drive train just remember not to be in full lock when turning lol.
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Old 05-19-2014, 11:34 AM   #6
3inchesoflove
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I have yet to use full lock, instead I set everything to full open manual for the most rear biased power delivery. Just wondering if this will wear the diff faster than auto -
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Old 05-19-2014, 12:00 PM   #7
trev762
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Quote:
Originally Posted by 3inchesoflove View Post
I have yet to use full lock, instead I set everything to full open manual for the most rear biased power delivery. Just wondering if this will wear the diff faster than auto -
In full manual open is not rear biased at all in 08+ sti.

In auto - is rear biased for 08+ just to mention for people to know for future reference.
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Old 05-19-2014, 07:11 PM   #8
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Quote:
Originally Posted by trev762 View Post
In full manual open is not rear biased at all in 08+ sti.

In auto - is rear biased for 08+ just to mention for people to know for future reference.
How does that work?

The DCCD (unless it has changed) varies the amount of lockup within clutch plates to achieve a maximum of 100% lock, for a maximum of 50/50 torque split. With less than 100% lock, the torque split biases toward the end with the mechanical advantage, which in previous designs was the rear end getting 65% of the torque at 0% lockup (full open).

I'm genuinely intrigued. Kindly explain the statement?

Jay
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Old 05-20-2014, 01:12 AM   #9
trev762
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Quote:
Originally Posted by Storm View Post
How does that work?

The DCCD (unless it has changed) varies the amount of lockup within clutch plates to achieve a maximum of 100% lock, for a maximum of 50/50 torque split. With less than 100% lock, the torque split biases toward the end with the mechanical advantage, which in previous designs was the rear end getting 65% of the torque at 0% lockup (full open).

I'm genuinely intrigued. Kindly explain the statement?

Jay
Full open manual on 08+ is 50/50 but open diff and think 02 to 07 was this type of torque bias.

08+ utilizes a torson diff not a clutch plate type.

08+ on auto is 50/50 split unless it is set to + or - torque bias split.
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Old 05-20-2014, 05:32 PM   #10
3inchesoflove
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I believe you are mistaken, just did a couple quick searches on Naisoc and found plenty of topics on how the center diff works, all of them and the subaru owners manual claim that the center diff is a planetary gear set with dual clutch plates to lock the diff.

The planetary diff is set to 41/59 front/rear with the clutch plates acting to lock it at 50/50.


as an example

http://www.iwsti.com/forums/drivetra...reat-info.html
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Old 05-21-2014, 12:13 AM   #11
Web Foot STi
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Quote:
Originally Posted by trev762 View Post
Full open manual on 08+ is 50/50 but open diff and think 02 to 07 was this type of torque bias.

08+ utilizes a torson diff not a clutch plate type.

08+ on auto is 50/50 split unless it is set to + or - torque bias split.

You are mixing up the rear LSD with the center DCCD LSD.

In the rear the STi '04-'06 used a clutch pack LSD and changed to a Torsen '07+.

The center on all USDM STi's use an electromechanical clutch LSD under DCCD control.

The '04-'05 uses a pure electromechanical unit with a 1:1 planetary gear set and a 35/65% natural torque split.

The '06+ uses an electromechanical unit augmented with a small mechanical component ~20% with a 1:1.1 planetary gear set and a 41/59% natural torque split.

I'm not going to try and explain the DCCD auto and manual controls as I barely understand them myself...


(The ~20% is an IIRC off the top of my head. It's been a while...)
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