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If this doesn't point me out as a new guy, I don't know what will... :)

I just traded my '02 RSX Type-S in for an '05 STI. It's a kick ass car, and I'm sure you see me around these forums quite a bit. :) Used to hang at ClubRSX.com.

Anyway, the questions:

DCCD roller swith: what ratios are associated with the different settings that this is set on? I know the lock is 50/50 (front/rear) but what about the rest? The manual is less than informative on that matter.

Boost guage: what does it measure exactly? MPs? I don't know what that is! I was under this impression this is measuing psi...?

Thanks!
 

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I believe that the arrows change the percent all the way down to 65% rear and 35% to the front and each arrow is 5% until locked. Don't quote me on this but that is what I think I was told.
 

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Discussion Starter #3
I'm pretty sure 35/65 (front/rear) is the default during Auto, so do you mean it goes to 65/35 (front/rear)?
 

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Yeah, turn the dial all the way back and you get 65% torque distributed to the rear wheels and 35% up front.

My boost gauge MY04 is measuring mega Pascals (MPa). There are conversion factors online to convert them.

1 megapascal = 145.037738 pound-force/square inch (PSI)

check out this thread for some good general turbo info.

http://www.clubwrx.net/forums/showthread.php?s=&threadid=69670
 

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The auto setting is NOT 50/50 lock that would cause wheel hop while cornering...

Auto adjusts the torque distribution based on accellerator position, braking force, and motion forces of the car.

The static position for the Auto mode is 35/65 F/R. i.e. That's when nothing's going on.

When you're under WOT and not turning the wheel, the DCCD goes to 50/50 Lock.

The DCCD can be adjusted from 50:50 up to a maximum of 35:65 torque split (front:rear).

When in automatic mode, the DCCD uses input from a yaw rate sensor that ensures optimum torque split when cornering.

This isn't to be confused with the science of the way locking and open differencials work. The ratios appear different. And can be very confusing in a 4-wheel system.

The STi system is complicated in that there are 3 differencials two of which are limited slip and increasing torque rates.

for instance...

You may have the the DCCD all teh way back(35/65) but if the front wheels are on ice(very smooth ice for the sake of conversation) then no torque can be applied to those axles as there is a dynamic contact relationship with the ground. The torque split then dynamically becomes 0/100 f/r This is because all the torque in the system that can actually be applied to an axle that has a static contact relationship with the ground goes to the rear wheels. that 100 percent of availible torque in the system is only 65 percent of drivetrain power and somewhere in the neihborhood of 75 to 100 percent of the engine power entering into the drivetrain as it takes considerably less power to just spin wheels as it does to hook up and launch the vehicle.

What they mean by 35/65 is the condition of the engine power when slippage has occurred... When you're driving aroudn on dry pavement and all 4 wheels have traction then it's inherently 50/50 torque split, no matter where you have the DCCD set.

It's when let's say.. all four wheels slip that the DCCD then allows UP TO 65% of the engine's input power to the rear axles... but if all the wheels are spinning at the same rate due to the gearing, then again, torque split is at 50/50...

See how it can get confusing?

It's more of a Bias than a static setting.

only when the front axles are moving at a different speed than the rear axles will the DCCD bias come into effect. for instance, if you're in 35/65 f/r manual mode and you put the REAR wheels on the ice, then you're only making 35% of total drivetrain system torque availible to the front wheels which are on dry pavement. This means that your rear wheels are going to spin ferociously but you're still going to move. You'd move quicker if you were at 50/50 lock.

Anyway... I hope that helps.

I know I"m gonna get flamed and argued with because there are those who feel otherwise.
 

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Vexamus said:
The auto setting is NOT 50/50 lock that would cause wheel hop while cornering...

Auto adjusts the torque distribution based on accellerator position, braking force, and motion forces of the car.

The static position for the Auto mode is 35/65 F/R. i.e. That's when nothing's going on.

When you're under WOT and not turning the wheel, the DCCD goes to 50/50 Lock.

The DCCD can be adjusted from 50:50 up to a maximum of 35:65 torque split (front:rear).

When in automatic mode, the DCCD uses input from a yaw rate sensor that ensures optimum torque split when cornering.

This isn't to be confused with the science of the way locking and open differencials work. The ratios appear different. And can be very confusing in a 4-wheel system.

The STi system is complicated in that there are 3 differencials two of which are limited slip and increasing torque rates.

for instance...

You may have the the DCCD all teh way back(35/65) but if the front wheels are on ice(very smooth ice for the sake of conversation) then no torque can be applied to those axles as there is a dynamic contact relationship with the ground. The torque split then dynamically becomes 0/100 f/r This is because all the torque in the system that can actually be applied to an axle that has a static contact relationship with the ground goes to the rear wheels. that 100 percent of availible torque in the system is only 65 percent of drivetrain power and somewhere in the neihborhood of 75 to 100 percent of the engine power entering into the drivetrain as it takes considerably less power to just spin wheels as it does to hook up and launch the vehicle.

What they mean by 35/65 is the condition of the engine power when slippage has occurred... When you're driving aroudn on dry pavement and all 4 wheels have traction then it's inherently 50/50 torque split, no matter where you have the DCCD set.

It's when let's say.. all four wheels slip that the DCCD then allows UP TO 65% of the engine's input power to the rear axles... but if all the wheels are spinning at the same rate due to the gearing, then again, torque split is at 50/50...

See how it can get confusing?

It's more of a Bias than a static setting.

only when the front axles are moving at a different speed than the rear axles will the DCCD bias come into effect. for instance, if you're in 35/65 f/r manual mode and you put the REAR wheels on the ice, then you're only making 35% of total drivetrain system torque availible to the front wheels which are on dry pavement. This means that your rear wheels are going to spin ferociously but you're still going to move. You'd move quicker if you were at 50/50 lock.

Anyway... I hope that helps.

I know I"m gonna get flamed and argued with because there are those who feel otherwise.
What source did you get this from?
 

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

who knows if he really knows what is going on, but if you read this link it makes sence.
Im somehow a source for that link :wiggles:

Vexamus got it right auto changes the ratio depending on what the sensors tell it.

As for manual mode locked is 50:50 open is 35:65 everywhere in between is everywhere in between the arrows are just there as a guide.

If you are curious as to how the whole thing work the factory service manual explains surprizingly alot of it. It doesnt say how auto mode decides what to do(ive seen that in other places) but it explains how the diff ratio is changeable, and how the ebrake works without messing up the center diff etc..
 

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afpdl said:
If you are curious as to how the whole thing work the factory service manual explains surprizingly alot of it. It doesnt say how auto mode decides what to do(ive seen that in other places) but it explains how the diff ratio is changeable, and how the ebrake works without messing up the center diff etc..
Which part of the manual is that in? "Mechanism & Function"?
 

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Digitalfiend said:
Which part of the manual is that in? "Mechanism & Function"?
Are you talking about the owners manual or the factory service manual? I believe it was under transimission or driveline and then you click on dccd and its there. Ill check on it tommorow.
 
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