W124 Rotor Retaining Screw Broken - PeachParts Mercedes-Benz Forum

MCallahan · #1 11-22-2018, 11:23 AM

The rotor screw is for assembly line production, it doesn't make any difference whether the screw is there, whether the rotor indexes to the hub pattern the same way or anything else. The screw is there to keep the rotor from falling off the hub while the chassis is going down the assembly line before the calipers are put on. You can run without it just fine.

If you just have to repair it, get a left hand drill set. You start with the smallest drill in the set and step drill up until you either get the screw drilled out to where you can pick the remaining threads out, or if you are lucky, the drill hangs up and the screw backs out. Left hand drill set can save you hours of work in many cases.

mpolli · #2 11-22-2018, 01:34 PM

I worked on a '02 CLK with a busted off retaining screw. As has been said this is not a critical part, but you might want to have it based on your personal preference. This was not the worst problem however, all 4 dust caps had been left off the caliper pin slide tubes. And the owner assured me that the brakes had previously been done by the local Mercedes dealer....... sad.

Anyway, I went to drill out the remainder of the screw in the hole. I had the hub off since I was doing the bearings also. I know I had a right hand drill bit, but I don't remember if I was drilling from the front or back of the hub. Anyway, the screw spun right out easily. It was actually loose. So the question is then, how do you break off a screw that is not seized? My guess is the mechanic had his impact set the wrong direction and snapped it off. Maybe he does them all that way and leaves all the caps off to help the pads wear faster... The caliper brackets hadn't been cleaned at all either. I remember being to this dealer and marveling at how clean their shop floor is (they have a big window you can see it through). Now I know why it is so clean!