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      12-14-2012, 04:03 AM   #68

Drives: 05 M3, 00 Z3MC, Boxster Spyder
Join Date: Nov 2007
Location: Huntington Beach, CA

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Originally Posted by Alex07M3 View Post
not really, the RS3 has a Haldex AWD system that put more power to the front wheels which makes it drive more like a FWD with no traction problems, not really representative of the rest of the line up. Even a basic A4 2.0t has an AWD system that put 60% of the power to the back wheels to favorise a sportier handling!
Actually the Haldex system distributes power 50/50 at all times when the car is being driven aggressively.

When the aggressive tuning for the TT-RS ECU determines FWD is not ideal, the Haldex electronically controlled center clutch immediately engages completely resulting in a 50/50 power distribution. So if you are cornering it will be operating at 50/50, and if you are accelerating in a straight line at low enough speeds or in poor enough conditions it will also be operating at 50/50 power distribution.

The advantage of Haldex AWD over a fixed 50/50 distribution is on say a 60-100 pull the car can operate in 100% FWD (center clutch fully disengaged) since this negates the inherent mechanical power loses of turning two axles for AWD when its traction advantages are unnecessary. Also gas mileage.

The downside obviously is the inability to run RWD biased, meaning for all intents and purposes during sporting driving the car is always going to distribute power 50/50.

The Haldex system works best when used in reverse on cars like the Aventador or Veyron due to their engine location, since for those cars it can vary from 0/100 rear biases to 50/50.