In a previous post, it was mentioned that with a 3 point harness, the top mount should be offset by a certain amount but i cant find anything in the manual.

Woudl it be ok to put the top mount backward so the harness goes round the back of the roll bar like this?

[img]
Proposed harness routing [/img]

very much doubt it. is it a 3 point harness, or a normal 3 point seatbelt (with diagonal top strap)?

wonder if you could use one of the roll bar bolts?
it says 8.8 grade 7/16unf or equivanlent strength, so maybe if one of those was a 12.9 and even slightly smaller than 11mm, wonder if that could work?

Its a 3 point seatbelt, sorry

How would a 12.9 <11mm bolt help?

well, what size are those roll bar bolts?

sorry, 12.9 grade 11mm bolt

[Edited on 30/3/10 by blakep82]

M10 8.8

here's what the manual says

"Note 3: A suitable single bolt fixing of adequate strength would be, for example, a bolt of at least 11mm (7/16" diameter of grade 8.8 (the grade may not be shown on a bolt produced for a seat belt anchorage). Other bolt fixings may be acceptable providing they are of equivalent strength. Two adjacent seat belts may be secured by one bolt. In this case consideration must be given to the additional loads on the anchorage"

so, i take that as, an 11mm with grade 8.8 is acceptable, you could go to 10mm (as per you roll bar) and using a 12.9 grade should make it stronger than a 8.8 grade 11mm bolt

Ah, sorry Blake. The belt mounting bolt is 8.8 M12. the rollbar mounting bolts are M10 8.8 but what i wanted to know was how far from the centre of the seat the seatbelt needs to be.

Here is a link to the previous post. Note DavidM's comment.

ah right, i get you.

well, i don't think it can be wrapped around a roll bar anyway, which is why i'm suggesting bolting it elsewhere.


ah, is this the answer?

"17.
A lap/diagonal belt “effective upper anchorage” location must be at least 140mm from the longitudinal centre line of the seat. (see note 14)"


i think its to nmake sure that if you did have a crash, the belt wouldn't try and slice through your neck

[Edited on 30/3/10 by blakep82]

quote:

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Originally posted by blakep82
ah right, i get you.

well, i don't think it can be wrapped around a roll bar anyway, which is why i'm suggesting bolting it elsewhere.


ah, is this the answer?

"17.
A lap/diagonal belt “effective upper anchorage” location must be at least 140mm from the longitudinal centre line of the seat. (see note 14)"


i think its to nmake sure that if you did have a crash, the belt wouldn't try and slice through your neck

[Edited on 30/3/10 by blakep82]

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i'd go with a 4 point harness tbh.

looks like you've got 2 mounting points welded in already up top. a 3 point harness will need one bolted down in the middle. 4 point will need them sort of where you've got them welded in now

In the SVA manual section 5 annexe 4, seat belt upper anchorage locations are specified. It gives a minimum offset from the centre of the seat of 140mm. It's the same section that specifies a minimum height for upper anchorage points measured from a block on the seat. I'm assuming IVA would be no less specific than SVA, but I've not seen an IVA manual.

David

[Edited on 30/3/10 by DavidM]

Presumably there is no minimum distance from the longitudinal centre line of the seat for four point harness'? Have read the whole of section 31 but can only see reference to the 140mm.

yeah, i can oinly see 140mm thing for diagonal belts. no mention for harness belts

That's correct, it's only for diagonal belts. The height requirements are for both belts and harnesses.

David

[Edited on 30/3/10 by DavidM]

Standard seat belt bolt are 7/16" UNF grade 5, bolt head marks are 3 equispaced lines see here.

http://www.elginfasteners.com/metric.htm

Imperial grade 5 is metric grade 8.8 approx

[Edited on 30/3/10 by wicket]

Thats great, cheers guys