Harness Bars/Roll Bars
"A roll bar will be required if harnesses are present. Harness bars are not acceptable substitutes, but they can still be kept for securing shoulder belts if a roll bar does not come with a rail suitable for attaching the belt."
Roll Bars (new for 2018, starting July 1) PCA Potomac Region
For 2018 the Porsche Club of America has issued new minimum standards for their driver-education programs (www.pca.org/driver-education-minimum-standards)
With regards to their Harness Standards they issued the following statement. "If the participant chooses to install a five or six point driving harness, several changes to the automobile must be made to create a safe occupant restraint system. Harnesses must: Include an antisubmarine strap. Have all harness attachment points secured/mounted in an approved manner consistent with the manufacturer's instructions. Be used in conjunction with a seat that has supplied routing holes for the shoulder and antisubmarine belts. Have the shoulder straps mounted at 90 degrees to the axis of your spine or at most 40 degrees down from the horizontal."
So Potomac has taken a strict interpretation of the new standards. Basically, what PCA is saying - if you are using a 5 or 6 pt harness they have to be mounted correctly, which means a roll bar or roll cage. Plus the seats must have harness slots - see below.
Harness (guide) bar
Although the seats have harness slots - this set-up will not be accepted. Harness bars are used to guide the straps to their correct mounting position. Not for the straps to be attached to them. Harness bars have not been designed or tested to survive crashes. Note harness bars, unlike roll bars and cages do not protect the roof of a vehicle in the event of a roll-over.
Roll Bars usually include a harness bar in their structure - see above. The harness straps can be attached to them since (if correctly installed) the roll bar has the strength and structure to survive impacts and roll-overs.
will this be accepted?
Here the harness is correctly installed and the sets have harness slots - but it uses a harness bar. Porsche acknowledges some "Four Point Belt Exception" for specific newer Porsche models. These are cars with seats and belts that have met the Federal Motor Vehicle Standard 209 - very car specific. Schroth does offer 4 point belts that also meet DOT standards because they anchor to the same attachment points as the cars seats belt. We do not recommend using 4 pt harnesses on the track, even with ASM technology. AND more and more amateur sanctioning organisations to not accept them - period.
This set-up is not safe. Best to continue to use your normal seat belts - it is what the seats with the air-bags were designed for.
Brey-Krause Truss harness bar
A harness bar that is likely to be accepted since it attaches to the structure of the Porsche Cayman.