Audi R8 2008 Service Training Manual page 38

Transmissions/Driveline
R-tronic Shift
The gears in the R-tronic transmission shift without
a mechanical connection to the selector lever.
Transmission Control Module (TCM) J27 drives electro-
hydraulic valves inside a hydraulic unit according to the
signals received. The shift control selector lever has two
stable fixed-lock positions: left and right.
From the left position, the Automatic mode as well as
upshifting and downshifting can be selected by tapping
the lever accordingly (A, +, or -). From the right position,
reverse can be selected. In order to shift into reverse,
the engine should be at idle when at a stop with the
brake pedal pressed while tapping the lever to the R
position.
R-tronic Transmission Shift Control Selector
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The transmission shifts into neutral whenever the lever
is moved from one fixed lock position to the other fixed
lock position.
The Sport function (S mode) is selected by pressing the
Sport button located next to the selector lever. Selecting
the S mode in the Audi R8 allows for even more sportily
tuned driving and shifting characteristics; shifting speed
is reduced, and the shifting point is set at a higher
engine speed range.