# Quattro Dynamic- Rear Bias



## Chris.Tomo (Jan 9, 2017)

Hi all,

Does anyone have any details on how the Quattro system works when in Dynamic? I have read that once Dynamic is selected, it is then rear biased which I have felt on a few occasions but does anyone have detailed information on the system?

Is it like BMW's X Drive where it is RWD until slip?
Or like the Subaru where it pushes a split with a higher percentage to the rear?

It would be great to understand it better.

Hope you can help!


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## Shaninnik (Sep 17, 2016)

TT mk3 has Haldex gen5 quattro, which is basically FWD until slips in normal conditions (Audi R8, Lambo Huracan has Haldex gen5 too, but it is inverted there). However I have found that TT really likes to send the torque to the rear and you can get really nice drifts or sideway action like on a RWD car, but only if you desire it to do it (dynamic mode, esp off). Dynamic mode just engages the Haldex fully to send 50% to the rear. If I am correct, it can not send more than 50% to the rear in normal conditions - technically it can, but only if the front begins to slip - theoretically if you will lift the front of your car so that front wheels do not touch the ground it will send all torque to the rear. I am not an expert so I can be wrong.

Despite all the talk about Haldex not being the 'true' AWD I really like how it works on the TT. It engages really fast, you can lock it in Dynamic, allows you to have some drift/sideway fun on the slippery road, but at the same time it is very predictable, stable and safe (my second car is RWD so I know what to compare). It also easily manages snow - I was able to drive in the snow which is higher than the car clearance whout any problems.


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## Toshiba (Jul 8, 2004)

R8 nor Huracan has Haldex, they use a reverse torsen Quattro (or big Q) systems.

When driving in normal conditions the Haldex is basically a FWD car with nothing much going to the rear. 
Only when the front starts to slip or lose grip will power goto the rear (based on a clutch plate) in any noticeable fashion (upto 50% so can never be rear biased). It is "Dynamic" in terms of its operation and not lockable, distribution is based on torque . Video is a little misleading in my view in that it talks about "modes" of ADS, but what it doesn't really say is that it works backwards, efficiency mode reduces the movement to save fuel.

OP a good write up is here.
https://www.carwow.co.uk/guides/glossar ... -explained

Videos
Torsen 



Haldex


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## brittan (May 18, 2007)

The Mk1 R8 used a viscous coupling to transmit drive to the front axle:
http://www.audi.com/corporate/en/innova ... attro.html

The Mk2 R8 uses a Haldex coupling to transmit drive to the front axle, although Audi call it _"an electrohydraulic multi-plate clutch"_. 
http://www.audi.com/en/innovation/quatt ... ch-r8.html

The equivalent Lamborghini models were similarly equipped.

For models with in-line engines, Audi are moving away from the old quattro system with the Torsen centre differential to "Quattro with Ultra Technology."

Very basically this uses a Haldex coupling between the gearbox and the prop shaft and another inside the differential. The effect is to disconnect the prop shaft and diff (crown wheel & pinion) from the drive train when 4WD is not required, reducing friction losses and therefore fuel consumption and emissions. 
http://www.audi.com/en/innovation/quatt ... ultra.html


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## tt3600 (Apr 8, 2006)

Interesting didn't know this...


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## Shaninnik (Sep 17, 2016)

Yes, I forgot to mention that I have meant mk2 R8. Wiki also says that Bugatti Chiron uses Haldex gen5 too, but I am not sure about this...defenitely not the same haldex as we have it. 

Regarding the 'locking' feature in dynamic - I can easily do doughnuts where front stays almost in place and rear spins like on RWD car - if the torque on rear was not locked it would simply tranfer all to the front, detecting the rear slip, would not it?

Anyway quattro on TT is fantastic


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## Chris.Tomo (Jan 9, 2017)

Thanks for the info, interesting stuff!


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