There should be a bolt in the disc with an allen end. not sur eon the exact size.

Tighten it and it will tighten the rotor down.

At least thats how it is on my benz.

Alon

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'92 300CE - Sold
2004 C240 - 744 - C7 Wheels - Android Radio
2002 C320 - 816 - Sport Wagon - Sold
2006 E350 Wagon - 368 - Dead
2015 GL350 Bluetec - 197U