i have spoken of this on many c3 threads... dont concern yourself on the measurement clearances. get the backside of the pulley as close as possible without touching anywere. then torque it and recheck. if you hear any grinding of metal at the front of the pulley its a bearing . remove the pulley press out the old bearing press in the new. hpautowerks has the replacemnet bearing or theres a thread on the c32 section of mbworld were a guy has a bunch for sale for around 25$