Adjusting Pretension
WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 2013 BMW 128i, 2012 BMW 128i, 2011 BMW 128i, 2010 BMW 135i, and 2010 BMW 128i. However, it is still accessible from the selected car via links, so may be relevant.
Remove rear window cavity cover strip
Turn adjusting screw (1) with special tool 51 2 220 until correct pretension is reached.
NOTE:
With soft top closed, side window glass (2) must run correctly into convertible top seals (check only when window cavity cover strip fitted).