With a HANS device, the maximum for belts is ~15-degrees up/down from horizontal at shoulder height.
You also want minimum distance back to where the belts are attached .... to minimise belt stretch in an "incident".
My harness bar has about 300-350mm of belt from my shoulders back to the bar (and my belts wrap around the bar - eye-bolts are best but warp-around is still serviceable.
You also want to adjust the shoulder belt so that the shoulder belt adjuster is near the top of the HANS at about collar bone level and the belts need to be cinched down "tight", really tight.
In an incident, the body will mo e forward and down into the seat and the HANS is designed to be gripped by the belt as your body slides under it a tad, which shortens the HANS retaining straps to prevent your head moving relative to your neck (which is the whole point of the device).
This PDF off the FIA website will do a better job than my description - it is from 2007 and you might find a more recent copy via Mr Google but it is what I used (and still use).
|