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Discussion Starter #1
I know that the the Touareg shared the same transfer case at the Cayenne (NV235).

I know that through NV's own documentation the NV235 shows 2 torque split ratios 38/62 and 47/35.
http://www.rsgear.com/articles/2004_09.pdf

I know that through the use of the gearing we can mechanically change the torque split to create a bias.

I know that the NV235 transfer case uses an electronically controlled clutch to lock the center differential and/or partially lock the center differential.

The NV235 is the same p/n for both the cayenne and the Touareg so the 2 different torque biases are done with the exact same transfer case.

My question is how?

I have read that mechanically the transfer case is geared for 38/62 torque split so if the clutch is not engaged or didn't exist or was unplugged you would get an open differential with 38/62 torque split (assuming all wheels have equal traction).

I have also read that the Touareg accomplishes the 47/53 split by partially applying pressure to the clutch at all times during normal driving and that this also creates premature wear on the clutches.

I haven't seem any complaints about clutch wear out in these transfer cases, which makes me wonder if this is true?

If the torque split is mechanically 38/62 and if we lock the center differential clutch that would make it 50/50.

I guess partially engaging the clutch would start to move more torque from the rear to the front as it partially starts moving towards a full lock which when fully locked would make it 50/50. So as the clutches tighten the 62 rear bias starts to drop down and the front bias starts to rise up.

So in reality the most torque that can be transferred to the rear wheels if all wheels have traction is 62% to the rear if the clutch was fully unlocked to 50% if the clutch was fully locked. Of course that changes if there is wheel slip.

But if this were true the center clutch would have to essentially be locked to make a 50/50 bias which meas it would be locked all the time even in normal driving which we know it isn't.

So I am wondering if Touareg's really are biased 47/53 but they've got to be somehow because even NV own specs start 38/62 and 47/53 bias.

I want to think maybe the Toureg's version of the NV235 had different gearing than Cayenne's version that makes the most sense but it seemed when I quickly researched it that the transfer case was exactly the same but maybe that's not the case.

Curious if anybody has information or links that might be helpful in figuring this out.

Thanks
 

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Discussion Starter #3
Thanks for that info.... I forgot to specify that this is only applicable to T1 & T2 with the locking differential. I know that the T3 and up use the more simple Torsen style differential.
 

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Discussion Starter #4
I believe this post on a Subaru forum answered my question.

NASIOC - View Single Post - Dccd Faq

It is NOT possible for the clutch to effectively change the torque bias when all four wheels have equal traction. This can only be done by the gearing in the transfer cases differential, or when a wheel or axle looses traction.

Locking and unlocking the differential using the clutch can only lock or partially lock an axle with less traction to the other axle with more traction to prevent most of the power from being sent down the path of least resistance (the axle without traction).

The only way the Touareg can have a different torque bias than a Cayenne is through different gearing.

Either we are dealing with 2 slightly different transfer cases (which I believe is the case) or the Touareg has a rear bias just like the Cayenne.

Here are some examples of how and when the clutch pressure may be adjusted automatically:

a) pressure increases when the vehicle starts moving, based on the accelerator pedal position

b) pressure decreases when the vehicle is turning

c) pressure increases when the front or the rear wheels start to slip

d) cuts off pressure when ABS is activated

e) decreases the pressure when the brake pedal is pressed and when the accelerator pedal is released

f) increases the pressure when the transmission is in first gear
 

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Discussion Starter #5
After a little further research the transfer cases are different and while they are basically the same unit the gearing is the only difference. I can presume that you could replace your touareg tcase with a cayenne tcase to get the 38/62 split if you wanted to.

Touareg transfer case p/n: 0AD341011N
Porsche transfer case p/n: 95534104014

Technically the Touraeg is still rear biased at 47/53!
 

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Interesting, so where is the gearing different?
the transfer case chain looks to be a 1:1 ratio are the differentials different?
Or is it the stepper motor which changes the bias?
 

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Discussion Starter #7
From what I understand the planitary gears in the differential change the bias.
 

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Discussion Starter #8
The planetary gears in the center differential are used to achieve asymmetrical torque split.
 

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How would one ever notice the difference? The only time you'd notice the torque split is when either the front or rear end is slipping, right? To do that, you'd have to be doing some crazy driving. At 5,000 lbs, I don't see these vehicles flying around corners at the local track. But maybe that's just me...
 

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Discussion Starter #12
Rear bias is better for towing and high speed cornering. 50/50 bias offers better traction so is safer and better for off-road.
 

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How would one ever notice the difference? The only time you'd notice the torque split is when either the front or rear end is slipping, right? To do that, you'd have to be doing some crazy driving. At 5,000 lbs, I don't see these vehicles flying around corners at the local track. But maybe that's just me...
Its actually pretty noticeable that there is still some rear bias left. In winter driving touareg is more tailhappy than b6 s4. And about going to track, well maybe not in summer, but there is just after two weeks the audiclub finland ice track day where I'm going.
 

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Discussion Starter #14
Its actually pretty noticeable that there is still some rear bias left. In winter driving touareg is more tailhappy than b6 s4. And about going to track, well maybe not in summer, but there is just after two weeks the audiclub finland ice track day where I'm going.
Ice track sounds fun to bad I'll prob never see one here in Southern California. Post some video would love to see it!
 
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