I have a full face G-force helmet that is SA 2005. It has threaded holes in the back of the helmet. Looking at Hans mounting instructions, those threaded holes are more rearward than they suggest if you are drilling your own holes.
Are those threaded holes for a different device? I have no problem drilling new holes, but it seems odd to have the threaded holes pre existing that far back.
IIRC, GForce had a competing device, it no longer seems to be available.
You can read about it at: http://www.circletrack.com/safety/ctrp_0301_helmet_restraint_system/index.html
Don49
Reader
6/6/12 1:48 p.m.
Those holes are for the G-Force head restraint. I use a Dfender with my G-Force helmet and just drilled new holes in the proper location.
I recall having some sort of similar problem. I tried drilling holes in the appropriate places but remember that the holes wound up in places that, for some reason now lost from my brain, were unusable with the HANS hardware. Buy a new, proper helmet is what I had to do, and you may also.