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Seatbelt Bolts


Guest danny88

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Guest chris brown

10mm are not big enough must be 7/16 or 11mm not that I have ever found 11mm bolts even today AFAIK even Japanese cars still use 7/16 for all belt mounts. As you say Andi it doesn't matter to you but anyone still to go through IVA it does.

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Guest mower man

7/16 UNF is the correct thread and size as long ago as when I did my apprenticeship up to the last belts I fitted have all been the same , whether its aworld std I dont know but Fiat Citroen Rolls Royce Lada Ferrari are all the same mowerman [ 11/16 spanner size not 17 mm] :acute:

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think we are confusing two things, the threaded mounts, 7/16 UNF only and the tube mounts, which you can get other sizes through. for example, early Zero chassis has lower seat belt mountings, fixed to chassis with 7/16 UNF thread. bolt anything else into it and it will not hold.

 

Early top mounts are just tubes welded to the chassis, you can fit 10mm bolts and 11mm eye bolts through and secure with lock nuts, although eye bolts have their own IVA problems.

 

but all must be rated 8.8 or above, A2 for stainless, lower than 8.8? no idea why allowed, or imperial three lines

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A2 is the material the bolt is made from, the strength is given in the next figure,

ie

 

A2-70 : 450N/mm2 yield, 700N/mm2 UTS: soft as *bleep*

A2-80 : 600N/mm2 yield, 800N/mm2 UTS: strong enough but rarer.

 

8.8: 660N/mm2 yield, 800N/mm2 UTS

 

 

Notably, the strength is defined by the ultimate tensile strength, whereas the yield strength is probably more informative. If using stainless for potentially structural applications, i'd only use 80 grade bolts.

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Just for interests sake when i went through SVA i used the imperial bolts for the lower mounts (from the sierra) but didn't have any long enough for the top tubes so i used M10 8.8's. They didn't even question them at SVA. Not suggesting you should try for IVA unless the rules allow for M10. I had a feeling the SVA rules were written in a weird way and seemed to suggest they could be as small as M8 8.8's.

 

Whilst M10's are obviously smaller than the imperial ones ~11mm i don't see a problem as we are using 4 point mounting rather than 3 so the load must be reduced on the bolts significantly.

 

But rules are rules so i guess if you are going through IVA check the rules carefully.

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