I believe that there is an adjusting nut on the spindle that you tighten to set the specified play in the rotor, and the socket cap bolt goes through the periphery of that nut to lock it at the position you set. Have you taken the grease cap off yet? It should be relatively obvious at that point.

Kurt

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- '79 240D - engine swap complete! Engine broken in! 28-31 mpg! Lovin' the ride!
- '86 190D (W201-126) - 2.5 NA engine, 5 speed, cloth interior, manual climate controls, 33-34 mpg (sold to forum member).