zzr1100rick2
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| posted on 18/12/07 at 07:10 PM |
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seat belt lower mounts sort of ?
Hi if i built a subframe of 25mm box for the seats to fasten to also the inner seat belt mounts
would i have to bolt the subframe with 7/16 or 12mm bolts with crush tubes
or could i get away with 8mm bolts and crush tubes
where its bolted to the frame
Hope this makes some sense Rick
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Peteff
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| posted on 18/12/07 at 08:04 PM |
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If you bolt the subframes down with four M8 bolts you will have 32mm of metal holding them, the seat belt bolts have to comply to the applicable
regulations.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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Confused but excited.
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| posted on 18/12/07 at 08:18 PM |
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quote:
Originally posted by Peteff
If you bolt the subframes down with four M8 bolts you will have 32mm of metal holding them,
?
Tell them about the bent treacle edges!
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snapper
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| posted on 18/12/07 at 09:00 PM |
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thats 4 x 8mm but not the same as 1 x32mm
[Edited on 18/12/07 by snapper]
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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Mr Whippy
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| posted on 19/12/07 at 09:41 AM |
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I think the question really is, why are you not mounting the seatbelts to the chassis like everyone else? You may incur the wrath of the inspector
when he thinks your sub frame is too flimsy. In fact he may be of the opinion that the sub frame should be bolted on with the same grade of bolt as
the belts themselves.
[Edited on 19/12/07 by Mr Whippy]
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zzr1100rick2
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| posted on 19/12/07 at 09:49 AM |
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Simple answer is its a robin hood and as such has no centre mounts
also most 7 style frames are made out of 25mm box so i would imagine it would be strong enough
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Peteff
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| posted on 19/12/07 at 10:46 AM |
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Lots of production cars have the clip part fastened to the seat base which slides on runners fastened to the floor by four M8 bolts. I know I've
welded quite a few when the floor they fasten to cracks due to flexing because some plus 15 stone drivers have been inflicted on them over the
years.
thats 4 x 8mm but not the same as 1 x32mm
Who would think of mounting a seat with one 32mm bolt?
4 x M8 bolts distributed evenly will hold a seat firmly, put a (hypothetical) 32mm bolt in one place through the same section metal and the seat will
move and fret the mount.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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Mr Whippy
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| posted on 19/12/07 at 12:14 PM |
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Well to be honest my three cars (Nissan, Toyota & Volvo) that have the seatbelt clips on the seat also have a very large bolt at that corner where
as the rest are normal size, so using small bolts all round would not be acceptable.
[Edited on 19/12/07 by Mr Whippy]
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matt_claydon
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| posted on 19/12/07 at 02:46 PM |
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In production cars the seat belt anchorages are subject to a pull test so as long as they are strong enough to pass it doesn't matter what your
subframes are fixed down with. For SVA there is obviously no destructive test therefore the examiner is likely to require more substantial engineering
than you would find on your tintop so as to be safe.
As to the 8mm / 32mm thing, what was trying to be said was that you cant compare bolt sizes like that. Four 8mm bolts have a cross-section of 200
square millimetres. This is only the same as a single 16mm bolt. Half the diameter give a quarter of the cross-sectional area, or put another way,
twice the diameter is four times as strong.
Also, as whippy says above, almost all the force from the seat belt anchorage will go through one bolt - it won't get distributed evenly between
all four.
[Edited on 19/12/07 by matt_claydon]
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