WARNING: This page is about a different car, the 2008 Audi A4, 2007 Audi A4, 2006 Audi A4, and 2005 Audi A4. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Measuring From Thrust Washer To Contact Surface Of Housing
Courtesy of VOLKSWAGEN UNITED STATES, INC.
Determined circlip is installed.
The distance "a" should be 164.14mm +- 0.04 mm if correct circlip has been selected.