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Discussion Starter #1
This is an excerpt from the owners manual (Page 13 Book 3.3):

"The intelligent technology off all-wheel drive can automatically lock the center differential up to 100% while driving (rigid connection). As a result, it is not necessary in most cases to lock the center differential manually..."

Can anyone explain this to me... do we have a Torsen type center diff?

Thanks for any clarification...
 

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Discussion Starter #2
I read this information on VW's site... seems to indicate 4XMotion has a 60/40 front rear power split so maybe the lock makes it 50/50?

4XMOTION® (Touareg)
The power of the Touareg engine is transmitted to the wheels via the continuous 4XMOTION® four-wheel drive system. This flow of power is handled by a transfer gearbox, which includes off-road reduction. The 4XMOTION® system also includes a locking central and rear differential.

In normal situations - dry road, even grip, constant engine power –the drive torque is distributed uniformly to the front and rear axles without slip. The four-wheel drive system is distinguished by a 38:62 distribution of power to the front and rear axles through a centre differential. A four-wheel EDL (Electronic Differential Lock via braking) also supports this adjusted power distribution. To improve tractability further both centre and rear differentials can be locked via the centre console dials.

4XMOTION® (Touareg) < Technical glossary < Volkswagen Technology & Service | VW Australia
 

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In the Touaregs, if you have 4XMotion (the two speed transfer case) you have a multi plate clutch and servo motor controlled Haldex center differential. If you have 4Motion (the single speed transfer case), you have the simple, robust Torsen center differential (same as the US military uses on the HUMMV).
(Note: other vehicles in the VW range use Haldex center differentials in their 4Motion drive systems.)
 
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Discussion Starter #4
Thank you for that info... do you know anything about the front to rear power distribution?
 

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The center differential lock is manual override which forces 50% to the front and 50% back. The rear differential lock is manual over ride that splits 50% left and 50% right essentially forcing 25% of the power to each of the rear wheels. You lock the differentials and you eliminate all the technology in the 4Xmotion.

T1 and T2 have a 50/50 bias while 2011+ has a 60/40 split.
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Discussion Starter #6
Here is the best information I have found at least regarding power distribution. I still don't fully understand the operation of the electronic controlled clutch I guess my assumption is that the transfer case can re-distribute torque when one axle looses traction but when locked it's always 50/50 regardless of which axle has traction. Can anybody confirm that?

The 1st generation Touareg (internal code: 7L) is produced between 2002 and 2010. The below #1 and #2 descriptions are for the 1st-gen Touareg:

1. 1st-gen Touareg 4Motion: it uses a planetary gear-set center differential, plus an electronically controlled, multi-plate clutch as the limited slip mechanism. It also has a low range gear. The center differential is manually lockable and this comes as a standard feature; in addition, you can also opt for the optional rear differential lock;

2. The DEFAULT front:rear power split ratio of the planetary gear-set center differential is 38:62, determined by the physical gear ratio. However, VW implemented an “always on” command into the multi-plate clutch control ECU program, which forces the limited slip to be always kicked in, which is sending an extra of 12% of torque to the front wheels by default. This effectively makes the final system power split ratio to be 50:50 under normal driving conditions.

The reason why Volkswagen did this was mainly due to the fact that Touareg is sharing its platform and some of the powertrain components with the Porsche Cayenne. Porsche wanted the front/rear power split to be 38:62 on Cayenne, while VW wanted it to be 50:50 on Touareg, and they do not want to design and produce two physically different center differentials (in order to lower the cost). Therefore, Volkswagen came out with this workaround, which uses a mechanical 38:62 center differential, and then tunes it to 50:50 within the software layer.

Because of this “always on” setting on the 1st-gen Touareg limited-slip clutch, the electric motor that operats the clutch pack is under heavy workload constantly, which leads to premature wear. It has been reported by some users that their 1st-gen Touareg need to replace the electric motor every 2-3 years.

Volkswagen Touareg 4Motion AWD System - A Comprehensive Review - YouWheel.com - Car News and Review
 

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Discussion Starter #8
Page 36 describes the NV235 used on the T1 & T2 Touaregs & Cayenne.

In Summary:

1. Chain Driven, Planetary Gear
2. 38:62 mechanical torque split but electronically using the clutch system redistributing 12% back to the front wheel make a final 50:50 torque split
3.Using the clutch system torque can be redistributed to either axle when loss of traction occurs reactively or possibly proactively because of integration with vehicles other electronics and traction control.

This might offer an advantage to the Torsen style in that the system can electronically change the torque split proactively or on purpose rather strictly reactively and also can be locked 50/50 which might have an advantage for off-roading.

The only disadvantages I can find are that they are heavier and more expensive but they seem to be one of the best light duty units made. They are lighter than the Torsen based unit NV225 used on the Land Rover Range Rover. They are expensive though over $3,000.
 

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But is there a way to make it act like in a porsche? There is no coding option so it must be in software. Does porsche have its own control unit and does work in vw? I doubt it.

And im talking about T1
 

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Discussion Starter #10
I thought the same thing... somebody could develop a device to allow the driver to change the torque split on the fly or like you said even possible to change it in the computer coding using the vag-com device if we knew what parameters to change and where to find them. It would be possible to make it strictly front or rear wheel drive. It would be fun to drive it using different settings to feel the difference.
 

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Does anybody found the way to code center diff splin in Treg to be like Porsche (38:62)?
If I had to guess, a swap of controllers way give you what you are asking for. The control units are so cheap on eBay it may be worth a try...
 
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