5 replies to this topic

[Rob Gendreau]

I'm installing a seat (Ultrashield Spec Miata) and a G-force 6 point harness.

When installed, the seat (16") is going to be on the floor, after removing the rear seat mounting humps. I'd like to use the existing seatbelt nuts in the tunnel and side rails. I thought about using the G-force eyebolts, but even with some reinforcement, like 4" plates, they'd still have to be behind the seat and to the inside a bit, which it seems to me would induce a squishing effect when pulled taut; I would think it's best to have them placed wider apart than one's seat/body (seems to be what the Schroth diagrams show).

Any problem with just using a 7/16" bolt, a coupla washers, and the stock webbing attachment? With the seat tight in there, it's a close fit, and I don't see any need to bent the attachment to make it point in; it's almost a straight pull. And there isn't any reason why that attachment should rotate, like the stock seat belt does, right? The belts always point the same direction because the seat's fixed.

Rob

[Keith Novak]

And there isn't any reason why that attachment should rotate, like the stock seat belt does, right? The belts always point the same direction because the seat's fixed.

The seat is fixed but belts do stretch and people do move around in a high G crash. Allowing the attach point to rotate helps to load the belt more evenly rather than have it pull and twist which will make it tear more easily. It also helps transmit the load to you better when you don't have one edge pulled tighter than the other.

[wheel]

The seat belt mounting rule says:

"The minimum acceptable bolts used in the mounting of all belts and harnesses is SAE Grade 5; hardware without grade markings is not acceptable." The rule has been clarified to say that you can use the mounting hardware that comes with the belts. ie. the eye bolts, etc. The eye bolts do not usually have an SAE marking on them, but they are compliant to the rules. If you bolt to the stock mounting holes, the bolts must have the SAE marking, or they will not be compliant.

wheel

[Rob Gendreau]

Thanks. I can maybe use a bolt with a narrow jamb nut to get a little play, while still having enough torque to hold the bolt to the frame. I am using grade 5 stuff. I thought of using an eyebolt, but haven't found anyone (at least locally) who sells a 7/16" eyebolt that's grade 5 or better with a collar on it (like the ones the harness companies sell).

Anyone have an online source that sells one or two bolts and has a really big selection?

Rob

[Ken Wilkinson]

http://www.mcmaster.com/#
If McMaster-Carr doesn't have it then you probably don't need it.

[Keith Novak]

A bunch of places sell the G-force 7/16 eye bolts. They're about $5. If you get one that's too long, figure out how much you need to cut off, run a nut down the threads, cut to length with a cutoff wheel and dress up the sharp corners on the grinder. When you unthread the nut that you prethreaded on the bolt it will act like a die and unbugger the end threads.