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Differential Tuning

Tuning the center differential provides one of the most significant
performance gains available to the Quattro owner. The standard torsen center
differential in the S4 and A4 provides a 2:1 torque distribution capability.
This enables the end of the car with traction (generally the rear) to
deliver twice the torque being delivered by the least tractive end of the
vehicle (generally the front). For high performance street cars, we
recommend a bias ratio of 4:1. This is the same bias ratio that Audi has
provided in the stock RS4 driveline.

In professional competition a high bias center differential provided a
performance gain of almost 2 seconds a lap. This is the equivalent of adding
60hp to an S4. This is our first step in almost every tuning project. It
provides a measurable performance gain for track-oriented drivers. For the
enthusiast street driver in good weather conditions, it can provide the
balance and control of a rear wheel drive vehicle, as 80% of the cars power
will be applied to the rear wheels upon corner exit.

The center differential in an S4 is a slip in cartridge accessible from the
rear of the transmission. The A4 center differential is a self-contained
bolt on unit. Install time is approximately 2 hours.

Center Differential rebuild A4/S4 - $500
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Rob Andrews
99 A4 2.8QS   83 Ur-Q
http://pages.sbcglobal.net/randrews


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