I did front rotors on my W124 this summer...I don't recall doing anything beyond unbolting the calipers (two bolts per caliper) and removing the hex bolt that holds the rotor in place.

anthonyb: There are two rods (not shown in your pics) that keep the pads in place...the holes just above the piston (in the pics) is where they slide in...actually the ends are serrated and you have to tap them in (or out) when replacing pads.

I guess this all depends on what year we're are talking about. This is all pretty fuss-free on the 93 model...

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car