Awd percentage

[Koom]

Speed stays the same but the 1.1:1 ratio gives a torque split at the centre cause that is what gear ratios do.

From Power = torque x rpm. Power is the same in both directions, rpm going forward is higher than that going to the rear so the torque has to be lower if that equation is correct.

[Optical]

The static torque split is made by a planetary gear system - this works independently of speed and diff ratio and also allows the dynamic torque split to vary depending on f/r wheel traction. The centre diff operates to mitigate the dynamic torque split.

[TurboMad]

Absolutely don't know a lot about this even though I drive one, but I have been trying to get my head around my setup and what's possible... Don't know if this helps or not...my car is 2015 STi and this from my manual.

Symmetrical All-Wheel Drive with Driver Control Center Differential (DCCD)featuring three performance modes and six driver-selectable differential lockingsettings;

mechanical and electronically controlled limited-slip center differential;helical limited-slip front differential and TORSEN® limited-slip rear differential,steering angle input sensor; nominal torque split is 41:59

So from the feel of the car it's 41 front and 59 rear on my cars standard setup

Edited August 18, 2015 by TurboMad

[gotasuby]

 Koom said:

Speed stays the same but the 1.1:1 ratio gives a torque split at the centre cause that is what gear ratios do.

From Power = torque x rpm. Power is the same in both directions, rpm going forward is higher than that going to the rear so the torque has to be lower if that equation is correct.

Yes 1.1:1 would give a different torque split but the rear diff is different than the from the front and if you multiply rear ratios together you get front diff ratio. Hence same speed and torque split.

And planetary gears in the auto and dccd boxes can allow a different torque split

[gotasuby]

 Optical said:

The static torque split is made by a planetary gear system - this works independently of speed and diff ratio and also allows the dynamic torque split to vary depending on f/r wheel traction. The centre diff operates to mitigate the dynamic torque split.

The viscous manual boxes are not planetary. Only spider gears and can not change torque output. Dccd boxes along with vtd auto boxes certainly can as they are planetary gears and have a rear bias torque output determined by the gear size.

[Optical]

Ah didnt know never looked at a non-dccd box!

[Guest]

 Optical said:

Ah didnt know never looked at a non-dccd box!

Baller.

[Optical]

Just leading a sheltered life lol

[lachlan]

taking the drive shafts out does not count ffs . dont be a twat .

completly a different argument to what the centre diff can do . and or oem torque splits .

and even then technically you are wrong . the clutch has not changed the torque transfer. if you lock the clutch you still have 5050 . you just removed the rear connection .

the fact is the dccd can not make the car act 0;100 or 100;0 . the dccd doesnt disconnect the front or rear shafts for you

[gotasuby]

 lachlan said:

taking the drive shafts out does not count ffs . dont be a twat .

completly a different argument to what the centre diff can do . and or oem torque splits .

and even then technically you are wrong . the clutch has not changed the torque transfer. if you lock the clutch you still have 5050 . you just removed the rear connection .

the fact is the dccd can not make the car act 0;100 or 100;0 . the dccd doesnt disconnect the front or rear shafts for you

Hahahahahahaha. You need to know when you are wrong. Instead of taking Driveshaft out maybe imagine wheels on ice or inside front wheel in the air with open diff. Or is that too hard for you. I'm not going to argue with someone not willing to learn so this is my response to you unless you ask a valid question. I'm only trying to inform everyone about the awesome capabilities of Lsd diffs.

[lachlan]

if the wheel is on ice or in the air then it is still receiving 50 % of the torque dumbass

i know exactly how it works .

i do not believe a dccd can make a car ( without axles removed) 100% front wheel drive or 100 % rear wheel drive .

please do educate me on how this is possible

Edited August 19, 2015 by lachlan

[cods4]

 lachlan said:

if the wheel is on ice or in the air then it is still receiving 50 % of the torque dumbass

i know exactly how it works .

i do not believe a dccd can make a car ( without axles removed) 100% front wheel drive or 100 % rear wheel drive .

please do educate me on how this is possible

This guy explains it well

[video=youtube;_HOa0aRZYpw]

Edited August 19, 2015 by Joker

[gotasuby]

 lachlan said:

if the wheel is on ice or in the air then it is still receiving 50 % of the torque dumbass

i know exactly how it works .

i do not believe a dccd can make a car ( without axles removed) 100% front wheel drive or 100 % rear wheel drive .

please do educate me on how this is possible

You just contradicted your self. you said a wheel in the air is still receiving 50% torque and you also said you know exactly how it works. LMAO i needed that laugh soooooo much. thank you sir you have done me a huge favour and my whole neighborhood is prob wondering where the laughter is coming from.

Please watch video and re educate yourself.

You are prob right that it cant make it quite 100% drive either way as there is losses in the driveline

[Koom]

 lachlan said:

if the wheel is on ice or in the air then it is still receiving 50 % of the torque dumbass

i know exactly how it works .

i do not believe a dccd can make a car ( without axles removed) 100% front wheel drive or 100 % rear wheel drive .

please do educate me on how this is possible

As Optical said earlier, the planetary gear arrangement of the dccd fixes the torque split at 35:65 due to the mechanical advantage. The clutch pack just prevents any difference in speed between either output (if locked, otherwise limits the speed differential or if it's open, allows one end to spin freely but that is still not 100% torque). i.e. you have all four wheels off the ground, you still have to apply a torque to one end to stop them rotating if you want the other to rotate independently so the torque split still applies.

That video also doesn't explain centre diffs that have a set mechanical bias at all. As in a planetary centre diff that in plain, straight ahead driving, will be putting 35% torque through the front axles and 65% through the rear. Then when slip is introduced, the clutch pack works to limit that slip rather than redirect/multiply torque. Clutch packs are just a reactionary part, because the slip comes from one end of the car losing the reaction torque from the ground (ice, mud, lifting the front with weight shift in drag racing.....) So the available torque from the engine is limited but not redirected to the other end of the car.

[Koom]

I'm going to switch camps on this (cause its not religion and I've done some more reading)

After looking at this thread (http://igotasti.com/vBforum/showthread.php/263-DCCD-info-and-FAQs), I never knew that the clutch pack locked up the sun and planet gears so that they couldn't independently rotate. Effectively making it the same as a locked 50:50 diff with no mechanical advantage for either end (rather than just limiting slip between the outputs). So then its back to a locked 50:50 diff can produce 0:100 or 100:0 effective torque at the wheels.

But in steady state i.e. driving along a straight road, it can still only be between 35:65 and 50:50.

I'm still unsold on the 1.1:1 discussion though.

Because there is always a 1.1:1 ratio in the centre of the drivetrain which cannot be locked up 50:50 to give an equal split.

Especially after reading comments by "patr" off Nasioc (i.e. http://forums.nasioc.com/forums/showthread.php?t=1660820)

 patr said:

almost.. except that spider gear sets and reduction ratios in the transfer gear sets actually can control how much torque is applied in the "locked" case or "locked before it slips" case in a viscous or emcd or otherwise plated diff. so yeah we are saying the same thing but your numbers are wrong in some cases. Its really really easy to see on the dyno, for example the 1.1:1 center diff cars vs the 1:1 cars (yes, when wheelspeed is the same, there is differential torque across the front to rear).

Still lost on what the rear diff was supposed to be when the gearbox had a 4.444:1 front and 1.1:1 centre. Technically it should be a 4.04:1 rear so with a 4.111:1 rear, there would always be a percentage of slip in the centre diff. Think it was a TY755v1naa? but I forgot to double check that last night.

[gotasuby]

 Koom said:

I'm going to switch camps on this (cause its not religion and I've done some more reading)

After looking at this thread (http://igotasti.com/vBforum/showthread.php/263-DCCD-info-and-FAQs), I never knew that the clutch pack locked up the sun and planet gears so that they couldn't independently rotate. Effectively making it the same as a locked 50:50 diff with no mechanical advantage for either end (rather than just limiting slip between the outputs). So then its back to a locked 50:50 diff can produce 0:100 or 100:0 effective torque at the wheels.

But in steady state i.e. driving along a straight road, it can still only be between 35:65 and 50:50.

I'm still unsold on the 1.1:1 discussion though.

Because there is always a 1.1:1 ratio in the centre of the drivetrain which cannot be locked up 50:50 to give an equal split.

Especially after reading comments by "patr" off Nasioc (i.e. http://forums.nasioc.com/forums/showthread.php?t=1660820)

Still lost on what the rear diff was supposed to be when the gearbox had a 4.444:1 front and 1.1:1 centre. Technically it should be a 4.04:1 rear so with a 4.111:1 rear, there would always be a percentage of slip in the centre diff. Think it was a TY755v1naa? but I forgot to double check that last night.

The 1.1 bit is after the centre diff. It's included in the ratio of rear diff. Subaru I'm pretty sure did it to reduce prop shaft speed and in rear rear diff strength. As you can run a larger pinion. The diff sees the same speed from front and rear as if you think of it this way. For every 1 turn of front wheels you get 3.9 turns of pinion to centre diff. And 1 turns of rear diff gives 3.54 turns of prop shaft. Then the transfer gears turn the centre diff 1.1 times faster or 3.9 times. Does that make more sense?

[Koom]

Just looked at my old notebook and it was a ty755vn5aa and the centre ratio was 40:37 which matches a 4.111 rear to 4.444 front.

It all seems so boring now if the 1.1 came after the centre diff. Mostly a moot point cause I destroyed the clutch pack in it too.

[Guest]

My v5 was running a 4.444 box and 4.111 diff. The centre was non existent.

[DRFVDR]

depending on the subaru model I have a real 4wd subaru ( brumby)an the first "AWD" subaru as well

[GC8E2DD]

Can you lock the centre diff in the Brumby?

[PUREBROWN]

Not sure bout brumby but i have a gen 3 outback and im going to source a dccd so i can lock it up at 50/50 momentarilly to get me out of situations. Aparently you cant use it to long as it heats up too much, have to do more reasearch on this but if your brumby has a later engine that you can bolt up a box to suit you might be able to make something work

[DRFVDR]

 GC8E2DD said:

Can you lock the centre diff in the Brumby?

The Brumby does not have a centre diff it is either FWD or 4WD