The needle bearing (013 981 94 10) looks to be a separately replaceable part of the K2 drum. Probably a press fit that will require a bearing/bushing driver to install.

The drilling/tapping is to allow replacement of O-rings that tend to get hard and cause fluid leaks and consequent clutch apply problems. These O-rings are not normally serviceable because they are held in by a piece that is riveted to the clutch drum (either K1 or K2). Look at the inside of the clutch drum with the piston removed; there will be a round aluminum part with "MERCEDES-BENZ" and a part number cast into it; this part has the O-ring under it and is held in place by three rivets. If you have the parts included in your rebuild kit you just drill or grind out the rivets which allows the aluminum piece to be removed along with the O-ring. Then simply tap the holes in the clutch drum to accept the screws supplied with the rebuild kit. Use a large drill bit to provide a countersink in the aluminum piece so the screw heads sit flush. Then use Loctite or similar on the screw threads, assemble the aluminum piece and new O-ring, then tighten the screws. Cut or grind off the extra screw thread coming out of the other side of the clutch drum flush with the drum. It's actually easier than it sounds reading this.

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Erich Loepke
2010 Ford Focus
Currently Benz-less