splitrivet
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| posted on 18/3/04 at 02:08 PM |
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Top Harness mounts
Hey up chasps,got me a couple of 4 point harness's from stafford not too sure on the mounting points for the top harness.
Is it ok for SVA just to drill and bolt thru the top rail and maybe sleeve it or must some other mounting method be used.
Any thoughts gratefully received.
Cheers,
Bob
I used to be a Werewolf but I'm alright nowwoooooooooooooo
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Alan_Thomas
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| posted on 18/3/04 at 03:07 PM |
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Search the archive for threads on this one. Many cars fail SVA cos of this. The usual reason is that the mounting is too low to get the height in the
SVA manual. I had to mount them on a Crossbar welded across the roll hoop about 3" above the top of the 'top rail'
Also the mounting needs to be strong drilling the top rail with or without sleeve would not have passed with my examiner.
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Fozzie
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| posted on 18/3/04 at 04:05 PM |
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Had to exact same as you Alan! Made slightly more complicated coz of the full race cage
The datum point for SVA meant that there was no other option.
ATB fozzie 
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splitrivet
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| posted on 18/3/04 at 05:17 PM |
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Looks like I'll have to go down that route luckilly Ive still got some roll bar tube left over, unless anyone else has any other ideas.
Done a search but all threads are a bit vague
Cheers,
Bob
[Edited on 18/3/04 by splitrivet]
I used to be a Werewolf but I'm alright nowwoooooooooooooo
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britishtrident
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| posted on 25/3/04 at 05:30 PM |
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Apparent ( http://www.gibbs111.fsnet.co.uk/centrall.htm) this high enough for inertia reel belt but a LOT will depend on the seat.
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macspeedy
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| posted on 25/3/04 at 05:53 PM |
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funnily enough looked at this the other day on the mk it is 7/16 x 20 unf a very fine thread
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Fifer
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| posted on 25/3/04 at 08:24 PM |
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I also bought a Harness set at Safford. As above, you need the correct hight etc (I made up a simple jig as per the book drawing) and watch if you are
passing belts through the seat holes if you have them, there are rules around this also as the seat comes into play if these slots redirect the belts.
(My Cobra Roadsters just make it for hight above base of seat but after calling Cobra, they assure me the top of the slots is just right for SVA, and
offered a letter to say so)
You must aslo ensure that the mounting is into a threaded collar in the tube / box, or, it can be right through a collar with a lock nut on the back
as long as you can access the lock nut.
Well thats my take on it anyway, we'll see in a month or so when Mr SVA has his day !!
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britishtrident
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| posted on 25/3/04 at 10:04 PM |
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quote:
Originally posted by macspeedy
funnily enough looked at this the other day on the mk it is 7/16 x 20 unf a very fine thread
7/16" was always the size & standard thread for seat belts until metric really took hold.
If you can find a 70s car in the scrapyards the seat belt mountings yield very hand thick (8mm or so) spacer washers for packing up the mounting
points.
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craig1410
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| posted on 26/3/04 at 12:06 AM |
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Hi,
I'm in the same boat here and am using Cobra Roadster 7 seats with harness slots. I don't like the way the book recommends placing little
pillars onto tube 'O' as this looks crap IMHO.
I like the idea of the crossbar on the rollbar but my rollbar doesn't have structural backstays (it has 38mmx16swg cater ham style backstays
instead) and is made from 48mm o/d x 3mm thick black pipe. The rollbar is welded to the suspension turrets and I think it is very strong and would be
fine for seatbelt mounts but I'm worried about what SVA will make of it.
My intention was to loop the harness over this extra bar and then actually mount the seatbelt end farther down behind the seatback on a 5mm thick
plate with a welded 7/16 nut behind it.
Do you think that SVA would go for this or would they be worried about the harnesses being looped over the rollbar. I suppose they could argue that if
the harness was removed, it could accidently be replaced without it looping over the rollbar and thus would not be at the correct height.
Anyone tried this setup?
Cheers,
Craig.
[Edited on 26/3/2004 by craig1410]
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PioneerX
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| posted on 26/3/04 at 01:40 PM |
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Question.....As I dont have the SVA book to hand, does anyone know if you must use 7/16th's or can I use a metric bolt (8.8 tensile stength of
cause)
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Fifer
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| posted on 26/3/04 at 01:43 PM |
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The book states, the bolts must be "at least" 7/16 diameter. But they can be any suitable thread or size above that.
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locoboy
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| posted on 26/3/04 at 02:39 PM |
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Craig,
I had an idea of doing what you are proposing by way of mounting the end of the harness down the back of the rear bulkhead.
I was told that the harness bolt must be in shear loading and not in tension, so make sure that you mount it correctly.Other than that i cant see a
problem with it
ATB
Locoboy
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craig1410
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| posted on 26/3/04 at 09:20 PM |
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Col,
Yes i was aware of the shear versus tension requirement but thanks anyway. I'm going to get bolted harnesses rather than the ones with the
eyebolts because I'm not sure how SVA friendly the eye bolt type are. The shear requirement is just that the tension on the harness should be
pulling the mounting bolt at 90 degrees to the axis of the bolt rather than trying to pull the bolt out of the hole directly. This should ensure that
the mounting will tear long before the bolt itself pulls out of the threaded hole.
Do you think I'll need to wrap the rollbar in plastic or something to avoid the metal to harness contact? Of course I will make the rollbar very
very smooth and remove any sign of a sharp edge.
Cheers,
Craig.
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craig1410
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| posted on 26/3/04 at 09:21 PM |
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PioneerX,
I think you would have to move up to an M12 8.8 grade bolt but I don't see a problem. I went with 7/16 UNF because it has always been the
standard for seat belts and should be compatible with most eye bolts and other fixings.
Cheers,
Craig.
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Fifer
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| posted on 26/3/04 at 10:41 PM |
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FYI
The SVA sixth ammendment (received today  ) has pictures now of whats acceptable, and whats not. pretty informative actually compared to previous
manual.
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Peteff
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| posted on 26/3/04 at 10:52 PM |
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I used M12 8.8 to mount my 3 point harness and it passed. It uses the welded on roll bar cross brace as anchorage and was fitted through a threaded
plate welded to the underside of the bar and taken back and then over the brace to take up a bit of extra length. The other ends are bolted to the
floor behind the seat with a large washer on the underside of each bolt.
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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craig1410
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| posted on 26/3/04 at 11:54 PM |
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Fifer,
That's good news about the new SVA manual, I have been wanting one for a while but didn't want to get the old version. I actually sent a
cheque away a while back but it was returned as the price had changed from £30 to £35. Can you confirm that it is still £35 so that I can send away my
order form again?
Cheers,
Craig.
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Fifer
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| posted on 27/3/04 at 10:29 PM |
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I think it is 35 quid. I was only getting my update for 17 quid so I would check the new full book price just in case.
By the way, on the upper mounting discussion, the new ammendement has little sketches of the threaded bush through the roll bar set up and one of the
acceptable ways shows a threaded bush, welded onto the roll bar tube along its side ! i.e. the bush is parrallel to the tube it's welded to.
Seems strange they say this is acceptable but they show a picture of a bush welded to the tube at right anges (but not penetrating the tube) and this
is shown as unacceptable !!
Best way is to do as stated above, insert bush thru tube, weld either side, and bolt seat belt mount with correct bolt all the way through.
Ah well, thems the ones that make the rules, we just have to develope the skills of a Philydelphia Lawer to work them out
Is that how yopu spell FILIDELFIAA
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highspeeddirt
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| posted on 27/3/04 at 11:27 PM |
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If the new manual is the same as the draft sixth manual available online then I think they mean you can weld the sides of the bush onto a chassis tube
in an upright position but not 'end on' on top of the tube. The text seems to make more sense to me than the pictures.
Steve
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Fifer
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| posted on 29/3/04 at 09:27 AM |
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Thats correct.
My limited understanding of weld stresses etc tell me that welding a bush in this way is much the same as welding a bush at 90 deg to a tube, i.e. the
forces are trying to rip the bush from one side of the tube steel, why one is acceptable and the other isnt, is a mystery to me.
My own car has the bush welded right through the x bar and threaded so hopefully it will pass
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blueshift
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| posted on 29/3/04 at 01:30 PM |
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Craig, I would guess you might have problems looping your harness over a tube, even if it looks quite smooth they might fail it on the grounds it
would chafe and eventually wear out. This is just my random paranoia though, I don't actually know.
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Peteff
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| posted on 29/3/04 at 03:15 PM |
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This is how I did it.
The plate is welded to the underside and the roll bar is welded to the chassis
 
Rescued attachment beltrear.jpg
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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Peteff
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| posted on 29/3/04 at 03:19 PM |
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The plate is 5mm thick and the bolts are M12x40mm and go inside the roll bar which was tapped at the same time as the plate.
 
Rescued attachment beltfast.jpg
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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britishtrident
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| posted on 1/4/04 at 07:36 AM |
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quote:
Originally posted by Peteff
The plate is 5mm thick and the bolts are M12x40mm and go inside the roll bar which was tapped at the same time as the plate.
The bolts aren't loaded in shear in fact the seat belt eye plate will act like a crowbar and try and rip the mounting boss out of it welds..
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Peteff
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| posted on 1/4/04 at 09:16 AM |
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It passed SVA. If that's not shear what is? The bolt is at right angle to the belt and the seat belt would have to shear the head off to break
loose. 12mm, it's never gonna happen. Your idea of shear and other people's probably don't coincide, I'll go with someone who
matters.
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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