Single seater harness mounting

[MikeBz]

With regard to how the shoulder belts are mounted to the vehicle...

My Caterham had the shoulder belts mounted on top-hat style spacers, so that they can swivel such that the load is taken evenly across the webbing where it meets the metal. This seems very sensible, indeed it appears very risky to me to have then bolted in so they can't swivel.

My newly-acquired Vauxhall Lotus is in need of new belts. The current belts are bolted in, as they generally are on single seaters, but have no spacers so they're not free to rotate. This means that unless the alignment is perfect (which it will never be) all the load is taken on one end of the webbing where it passes around the metal - so in a shunt all of the load is taken in maybe a 1/4" width of webbing, and when that progressively shears the load will progress along the width of the webbing but only ever being spread over a small width - so it'll just tear through. Hmm.

Flicking through the glossy catalogues I see that most bolt-in type harnesses have 8.1-8.5mm holes, which doesn't allow for any kind of spacer. So, what is common practice in single-seater land?

And while on the subject, the Caterham had a non-standard (high tensile I guess) bolts supplied with the belts. Is it normal for 'special' bolts to be provided with belts?

Mike