Porsche 911 GT3R 2010 Technical Manual page 76

6.3.2. Rear axle
6.3.2.1. Ride height
reference plane
The car must be placed on a level surface (set-up platform) to check the
ride height. The front and rear suspension should be loaded and unloaded
(compressed) several times to allow the suspension to settle.
Ride height adjustment is made by rotating the spring perch.
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