Thread size of safety-belt fitting bolts?

[Duncan Wood]

Because you've cut it, forming a thread conveniently leaves the root in compression which minimises the tendency to fracture. Plus if you look thread forming bolts tend to be 10.9 or 12.9, not "normal bolts". & as they've formed the thread it's undersize, so they self lock. You can just buy them from Ford, the ends are in free space so 2nd hand ones tend to be corroded past useful unless you find a fairly new van. Ideally you're never going to try loading them, but you'd really like them to hold if you do.

[Chris Whelan]

It wouldn't necessarily if you used a tap in a hole of the correct size for that tap.

If you use a tap in a hole that is intended to be threaded with a thread- forming bolt, it may well be sub-optimal. The required sizes are likely to be different; the larger the thread size, the more significant this may be. You would need to look in engineering handbooks and manufacturers catalogues if you want to be certain.

Also, the way the thread is formed will give different pull-out values.

Back in the real world (of car seat belt mountings at least), that's exactly what I would do.

Chris

[John Stumbles]

Thanks folks. I'll see if I can find a nut of the correct thread to put on to back up the one cut in the floor insert. Or check out the availability (and outrageousness of pricing ) of a thread-forming bolt and torx adapter to drive it with.

[Bruce]

There are plenty of companies offering parts for camper conversions of panel vans who stock the necessary parts.

For example: