I have Penskes with the newer black coilover spring perch adjust (my old coilovers were red).
When I installed these I was careful not to over tighten and strip.
However, I am having an issue with my left rear. It is tightened all the way so that it is snug (not stripped, adjust bolt is tight). However I can still turn the collar with my hand (and the collar threads are not also turning). I can see that the design of these is different than others that I have seen. The collar ends meet each other exactly where it wraps around the threaded cylinder. In other words if the tolerances in the manufacturing were not perfect then when you tightened it the collar would not be tight if the ends meet a very teeny teeny bit too soon before it is tight. I have seen some other brands that have a 1/4 inch gap so this problem could never happen.
I do not have time to replace it now and want to do some kind of temporary hack. I see two choices. 1) loosen it all the way so that the gap opens up and try to gently file one of the ends so that it is fractionally shorter then tighten it again (perhaps there is a burr caught in the gap) 2) piece of duct tape (obviously temporary).
Has anyone else seen this problem?