The reason I mention the great possibility of the steering wheel being off centralization due to previous alignment work rather than steering wheel removal and non-indexing upon re-install [ which will result in same condition] , is cuz all the years I have talked to alignment people ,[aside from Benz Techs] I have SELDOM, if EVER ,come across any that are aware that Benz has a centralization feature on the steering box that has to be set BEFORE doing toe adjustments. Most align guys just set the SW approx and lock it with a mousey fixture to the seat !!!!!
For those not familiar with this simple feature:
.. there is a 12mm cap on top of the box. This is an inspection hole that one screws an index pin into and that drops in a detent hole in the steering mechanism. When these are lined up, the steering system is at Neutral degrees +/- and Centralized and the pin is threaded in to LOCK the steering. This should also result in straight steering wheel in refence to vehicle lateral travel. The reason they do this is to assure that the steering has exact/equal movement measure on BOTH right and left turn axis .
The actual tool is Benz part# 111 589 00 23 -Center Position Check Screw..
One can be easily made from a bolt of proper thread sizing and cutting the protruding end to a V point with a slight rounding of the tip.. for quick checks, a phillips screwdriver with a .250" shaft will get you to the hole lined up enough to see if steering wheel is in alignment with Factory box alignment.. With the tool in lock position, the toe is then set and one is assure the system is correctly centralized position prior to tie rod adjusting..
Try that one on your alignment guy next time you go.. my bet is he looks at you like you'r nutzzzz.
.. one wants to remember .. toe is not really measured from tire to tire, it is actually measured from chassis lateral C/L., equally on each side from C/L.... Again, Centralization..
* As an added note .. the rear axle also should be checked for centering specs , as this is also in the equation to the steering geometrics of the vehicle. Your are looking for the swing hanger pivot pin center to be 36 mm ,+/- 2 mm, to the right of the chassis center line ..
The archieves has info on this procedure along with another homemade measuring tool ... correction here is the rear axle cross strut length adjustment ...