[Walt Fricke]

Kevin

Given the enormous strength of the forged eyes, I'd not think that the bending moment when mounted horizontally would be an issue. The FIA specifies withstanding a 25G load for belt anchors, and from (perhaps faulty) memory I think there is or was a US Federal spec of 3,000 lbs for anchors. Do you think such eyes would fail (not just bend) if these loads were applied perpendicular to the plane of the eye?

This is an inventive idea for drivers whose driving position allows installation of the anchors this far back while still maintaining the optimum lap belt geometry. I'd be inclined to a belt and suspenders here, with the threaded eyebolt extending into the tunnel, and a 3/16 inch custom backing plate inside the tunnel with holes to match. In this location you ought to be able thread the nuts on on the inside, and tighten them. A little Loctite blue would deal with any worries about nuts backing off, as these anchors don't get repetitive loads of any significance. In such a design I'd want to be sure that the upper nuts or whatnot were drawn firmly down onto the sheet metal, the beter to resist any bending.

That ought to insure that the cross piece could not twist much.

Could not an engineer equipped with the modulus of elasticity of the hardware store cold rolled steel (and it is not weak stuff, just not as strong as the higher priced stuff) used in this actual design, and the dimensions and the loads ,calculate, without even resorting to FEA, how much movement there would be in these anchors if both were simultaneously loaded in the forward direction (driver and passenger loads)?

Compared to the stretch in the belts, my instincts tell me this should be insignificant, but that's not engineering.