Cam sprocket: torque, secure fit
 

The cam shaft timing belt sprockets are not 'keyed' like on the 1.8T. Instead, once timing is set, they are just held by the torque on the cone seat.

Doing it 'by the books', I once torqued those bolts according to spec, only to find out after the warm up run that both sprockets had 'slipped' a few degrees from their original position (enough to make me redo the timing). A scary thought, obviously, to imagine those sprockets slipping on their shaft.

What is the 'best practice' to secure those sprockets on their cam shafts?
- how to clean/prep the cone seating surfaces? (Brake cleaner, for good, no oil grip?)
- how to torque ('as hard as you dare', 'to spec', else?)

I just snug them down tight, Obviously dont go crazy and keep trying to tighten it till the head snaps off. Torque specs are a guideline, and really only important for Head bolts and rod and main caps. Just make em nice and tight, have never had one come loose.

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I just checked: they are M10 (16mm sockets).

Spec says 55 Nm.
Engineering spec (standard) says for M10x1.5:
9.8: 56 Nm
10.9: 72 Nm

I will give it a standard 'nice and tight', then set the torque wrench to 60 Nm and see that it 'clicks'.