[BuzSTid]

it is great fun to be going along at a constant rate (or accelerating) & turning it to #

[STUKA]

I give this post 5 stars!!!!!!!!!!!!!!

[Subie 2.5 STI]

great write up

[ake109]

I am confused by many of the reviews and magazines and damn Subaru literature itself!

Can anyone clarify?

If I set the DCCD to 41:59 (F/R) using the manual mode, does it mean it is forced to stay at 41:59 even if one axle is spinning in the air? Or is that just the split when all wheels are gripping and once any set loses grip, the computer takes over.

I always thought that Subaru's can split their torque from 100:0 to 0:100. However the impression I am getting now is that this 08 STI can only vary between 50:50 and 41:59.

That seems like a really narrow range!

[waktasz]

Doesn't the DCCD only limit the amount of slip allowed front to rear? The gearing of the diff is always 41:59.

[fry_ed]

Originally Posted by ake109

I am confused by many of the reviews and magazines and damn Subaru literature itself!

Can anyone clarify?

If I set the DCCD to 41:59 (F/R) using the manual mode, does it mean it is forced to stay at 41:59 even if one axle is spinning in the air? Or is that just the split when all wheels are gripping and once any set loses grip, the computer takes over.

I always thought that Subaru's can split their torque from 100:0 to 0:100. However the impression I am getting now is that this 08 STI can only vary between 50:50 and 41:59.

That seems like a really narrow range!

waktasz is correct.
so what you're really asking is what happens when you set the diff to OPEN?

Doesn't matter if the wheels are gripping or not, 59% to the rear, 41% to the front.
If one set is in the air, then they will spin. How much load (torque) is being applied to the spinning wheels? not much.
so the set that is gripping will not be able to apply much load either. i.e. doughnuts

wouldn't want to jack up one set and try it though, because the gripping set might take some load. especially on the 06+ Stis where totally OPEN is not possible.

To answer your second question: yes, that would be a narrow range. yes, that is incorrect. 100:0, 0:100 IS POSSIBLE, in LOCK (wheel velocities forced to be equal between sets)

[ake109]

Thanks for the clarification guys. Me still nooby on AWD (is 4WD considered a heretical term round here?)

So in a nutshell, am I right to say :

1. The DCCD and the manual settings controls F/R slip only? i.e. When set at 41:59, it lets the front wheels spin 41 rotations for every 59 rear wheel rotations?

2. The amount of torque sent to the front/rear is independant of the above setting and up to the car?

i.e. Am I confusing slip vs torque split?

[deeksmooth]

EDIT: made new topic in tech discussion 08.

[OLi]

there is something they didn't say, on manual mode when the torque is not 50/50, what is the other maximum repartition ? 0/100 (f/r) ?

[waktasz]

The torque is always the same 41/59. The DCCD limits the slip allowed in the center diff.

[OLi]

thanks

[OLi]

You said the repartition of torque can only be between 41/59 to 50/50 but i see on some website it can be between 75/25 to 5/95 (French website: Nouvelle Subaru Impreza WRX STI: 300cv disponibles - emotoauto ) and other website say what you said. Can DCCD be different on European model ?

Sorry if i make some error, English is my second language.

[jrdriller]

Originally Posted by OLi

You said the repartition of torque can only be between 41/59 to 50/50 but i see on some website it can be between 75/25 to 5/95 (French website: Nouvelle Subaru Impreza WRX STI: 300cv disponibles - emotoauto ) and other website say what you said. Can DCCD be different on European model ?

Sorry if i make some error, English is my second language.

Bonjour

French is not my second language but I did growup in Canada and I've lived in France (Bailly, just outside Paris). You will find this link usefull. just remember that the 2008 STI center diff gear ratio is no longer 35:65 or truely "open"

DCCD FAQ

I think that a lot of journalist do not understand what they write about which creates a lot of confusion

[OLi]

thanks

Yes i was very confused (just about manual mode) because some website didn't says the same thing and we don't know who what is true and false.

[fry_ed]

Originally Posted by ake109

Thanks for the clarification guys. Me still nooby on AWD (is 4WD considered a heretical term round here?)

So in a nutshell, am I right to say :

1. The DCCD and the manual settings controls F/R slip only? i.e. When set at 41:59, it lets the front wheels spin 41 rotations for every 59 rear wheel rotations?

2. The amount of torque sent to the front/rear is independant of the above setting and up to the car?

i.e. Am I confusing slip vs torque split?

1. I can apply torque to a wrench in order to tighten a nut, and the angular velocity is zero. I can apply a torque to spin a top and have a very large angular velocity.

If you had 100 lb*ft of torque coming from your engine, then when you set it to OPEN, 41 lb*ft would go to the front axle and 59 lb*ft would go the rears. For simplicity, think of the front/rear relative rotations as being independent of each other.

If the fronts were to be on asphalt and the rears on ice, then the fronts are the "nut" and the rears are the "top", to complete the analogy.

I think that also answers your "2".