Am I better welding my insert to the back of the chassis bar or drilling right through the chassis bar and welding the insert there (just worried about this weakening the chassis bar)???
Cheers,
Pat...
.JPG)
Hi,
Am I better welding my insert to the back of the chassis bar or drilling right through the chassis bar and welding the insert there (just worried
about this weakening the chassis bar)???
Cheers,
Pat...
And another pic:.JPG)
id drill it through and weld it top and bottom 
Welded to the back it would be weaker. The chassis bar you drill through wouldnt be excessively
weakened IMHO obviously
Mine are welded to the back, haven't had any problems
Ray
Most seem to weld it to the back of the tube, if the top of it is level with the tube , hieght could become an issue at SVA , depending on seat squab
thickness, my mounts where about an 1" above that tube , and I needed a mega thin haemorroid splitting seat squab for the test!!!
[Edited on 21/7/05 by Surrey Dave]
one example from the 'book' was to extend the tube down to the lower O tubes. This should prevent twisting to the top tube if the mounting points are too high.
IMHO that wont take a lot of stress!
It will twist and turn under 'load'.
It will not pass SVA like that.
Pat you must remember (as dave previously has said), to think about the datum point height.
HTH Fozzie
I wasn't going to weld it where it was - it was just in the pic so you could see what I was going to use!
Think I'll weld my insert on the back of the tube with the bottom of it level with the bottom of the tube. It' 2" long anway and I can
drop the seat 1" by removing the runners just before SVA.
Cheers,
Pat...
I found that with my 'Oddessy' seats I could not get the mounting above the SVA height welding the inserts anywhere on the top chassis rail.
I was going to fit a roll bar anyway so I added another horizonal bar made from rollbar tubing (suprisingly light!) about 3" up from the chassis
rail and the inserts fitted thru the tube.
No problems with SVA or strength.
- Alan
quote:
Originally posted by Alan_Thomas
I found that with my 'Oddessy' seats I could not get the mounting above the SVA height welding the inserts anywhere on the top chassis rail.
I was going to fit a roll bar anyway so I added another horizonal bar made from rollbar tubing (suprisingly light!) about 3" up from the chassis rail and the inserts fitted thru the tube.
No problems with SVA or strength.
- Alan
Like these Fozzzzzzzzzzzzzz....
Rescued attachment blue and my locosts vsml.jpg
discussed before, but this was my solution. i wasn't happy with the idea of welding to the back of the top rail due to the twisting forces
(moments) that would act in the case of an accident situation.
i added some small additional 1" rhs pieces to the top rail to increase the height to ensure sva compliance with the harness mount height, i also
drilled right through and welded my threaded tubes top and bottom, then also added some more bracing down to the top dif mounts to resisit the top
rail twisting under the load of 2 people in the car at 2g under accident conditions, so say 80kg each person thats 320kg in total in an accident
situation which is over half the weight of the car trying to pull the top rear cockpit chassis member with your harness mounts in from the rest of the
chassis. 2g may be on the conservative side too depending on the type/speed of impact, you may think i went ott but i consulted some very experienced
engineers to reach my own solution, think about it, its your safty above all else.
all imvho of course.
Ned.
cockpit bulkhead
[Edited on 22/7/05 by ned]
I've just done mine to a bar between the rollbar verticals. I wanted to do it similarly to Ned's but my seat squabs are pretty thick and I
couldn't come up with a way of getting the 460mm otherwise.
SVA manual says it needs to be able to stand something like 10G IIRC and that may be OTT but just to be on the safe side!
HTH,
James
quote:
Originally posted by Surrey Dave
Like these Fozzzzzzzzzzzzzz....
I like the idea of the aditional horizontal tube in the roll bar, but I would just wrap the harnesses around the tube rather than drilling/welding/bolting them to the tube.
Rorty, Wrapping the harnesses around the tube, would be a definate 'no-no' with the SVA man.
Mr SVA man 'likes' to see a belt and braces approach to the harness mountings. In my case it doesn't just rely on the welding of the
tube, but is also very well connected to the chassis....well strong!
ATB Fozzie
[Edited on 28/7/05 by Fozzie]
I think there would be issues relating to the stitching of a seatbelt around the tube or the use of slider/tensioners in such a scenario aswell.
Ned.
You could run them from the back of the chassis tube and sling them over the tube across the roll bar without any problem to get extra height as long as the rollbar tube is smooth. We got one through like that and it helped take up some of the extra length of the belt.
Wrapping the shoulder belts around a roll cage tube is standard practice in motorsports. There's no stitching involved, you just thread the belts
around the tube and back through the manufacturer-supplied buckles. Have a look at any harness manufacturers web site and you'll see the
set-up.
Folding the webbing and passing it through a small bolt-on fitting isn't as good as wrapping the belts because wrapping the belts around a tube
causes far less fatigue in the webbing.
I'm supprised SVA don't prefer the belts to be wrapped rather than bolted.
Simpson wrap around.
Safe Quip wrap around.
Autopower wrap around
Wrap around installation.
[Edited on 29/7/05 by Rorty]
2nd link, bottom-most picture on the left.... I like it!!!!
Does it come with a quick release!
James
Right - further thoughts.
I don't want a horizontal bar in my hoop so...
1) Can I use just one mounting point for each side???
2) No problems with the 460mm as the moutning eye is about 468mm from the seat squab.
3) The tube will be seam welded with a triangle gusset on the inside.
Rescued attachment 1.JPG
And another pic:
Rescued attachment 2.JPG
If you mount those "posts" at that height, you'll either rip them out of that small tube or you'll rip the tube out of the chassis
when you put some serious strain on the belts...like in a frontal shunt.
The only way I'd attach a seat belt eye to that tube would be to weld a saddle to the tube and then weld the crush tube at an angle
through it so the belt eye is in line with the angle of the shoulder belts. That tube is just too small and light weight to do what you're
intending. But, it's your life.
What's more, if you have a low speed shunt and don't tear that post and tube out, you'll probably fracture your skull on it when your
head whiplashes.
Don't forget, the shoulder belts are supposed to be well below shoulder height and at an angle of about 35-40 degrees when tensioned over the
driver's shoulders. If you fit those posts as you've illustrated, the pull will be at the wrong angle, further compounding your problems.
Wrapping the belts around that tube would be a far more acceptable solution; they will find their own strain angle and would spread the load over a
much wider area.
More here...
and here.
I just can't see that passing SVA...at least I would like to think it wouldn't pass.
But in essence, it exactly the same as Stuart Taylor and MK...all be it with an additional triangular husset on the front.
Pat...
quote:
Originally posted by Avoneer
But in essence, it exactly the same as Stuart Taylor and MK...
Pat:
I kinda agree with Rorty here. I think a second bar on your roll bar is in order. If I understand right, your idea seems a bit questionable.
For my mounts I did this: I welded a 3/16" plate on the underside of the upper chassis tube. Then, I drilled through the tube (and the plate) and
inserted a 2" long crush tube with an ID of 5/16". I then welded the top of the crush tube around on top and bottom. On mine, it is maybe
1/4" proud of the upper tube.
--HTH, Chris
Rorty is correct. At best those posts will bend, allowing your head to get closer to the steering wheel then you can imagine. At worst they wrench
the tube sideways and rip out, allowing your face to impact the wheel.
However I disagree with the shoulder strap angles... follow this guide, http://www.gforce.com/pdf/harnessinstall.pdf
[Edited on 7/29/05 by kb58]
KB, I think the shoulder belt angles in that document are way off. It's an ambiguous and contradictory article at best, which seems to have been
cobbled together from several other on-line articles.
They go to some lengths to explain how the human body stretches in an accident, yet they still recommend a shoulder strap angle of up to 30 degrees
above the driver's shoulders!
I just looked up harness mounting in the CAMS Manual. CAMS is the Confederation of Australian Motorsport (the equivalent of the MSA in Britain) and is
overseen by the FIA, so I figure if anyone would know about harness installation, they should. Interestingly, the manual states:
Schedule I - Safety Harnesses / Window Nets.
4 (ii) Full harness rear mounting points must be to a substantial part of the vehicle's structure, reinforced as may be appropriate.
(iii) On production cars, the original mounting points may be satisfactory.
I tried scanning the page with the diagrams, but the book is too stiff and the drawings feint, with the result it scanned poorly. But, CAMS recommend
the shoulder straps be up to 10 degrees below a horizontal line extending from the driver's shoulders. They further state anywhere up to
40 degrees below the same horizontal line is acceptable. That roughly supports what I said initially above.
They also show a drawing of a driver in a laid back seating position with a note stating in any event, the shoulder straps "may be best set
perpendicular to the upper spine".
In everything I ever read, saw, or was told about harness installation (including several safety lectures while an official scrutineer) the shoulder
straps should always be attached to the vehicle at some point below the driver's shoulders - never above!
The reasoning is, if the car was to flip, the driver's body can distort and if the straps rise above the shoulder line, the driver could squeeze
up into that area above the shoulders with the possibility of the driver's head contacting the upper roll cage or roof.
I've seen that happen with very unpleasant results. I would never allow a car on the track that had upward sloping shoulder straps.
Please bear in mind that after SVA, they will be cut down flush with the top of the chassis bar.
Pat...
quote:
Originally posted by Avoneer
Please bear in mind that after SVA, they will be cut down flush with the top of the chassis bar.
Pat...
well you've seen my previous suggestion and theory, I'd tend to agree with Rorty on this, and i'd personally go for a 4 point instead
of a 3 point harness. can't give a good reason for this (other may be able to help me out here) but a 4 or even 6 point (if for track use) is
much better than a 3 point imho.
Ned.
I really do not want to get into any arguments here, I do not want to tell anyone how to build their car, or 'wee' on their fireworks,
but, I will say something if I do not think it is safe. I too have been involved in motor sport for many years, and part of our business is to prepare
cars for the race track, here in England.
I may have misread or indeed got this wrong, but I assumed that Pat (Avoneer) just wants to put his 'Book' Locost on the road, (SVA) and not
race it. That does not in anyway detract from advising the best possible harness thats available, but thats where we are governed by the SVA
'rules'.
The harnesses have to be of a certain type and 'E' marked, you MUST consult the SVA manual before purchasing them.
My car was built for road and race, and in my case, the belts I wished to use were not on the 'approved' list for SVA, although in theory
they were a lot safer, but the object was to get the car on the road first and change things if necessary later to suit the race regs and the
'Blue Book' (MSA).
Down here in Surrey, at the time of my SVA, they had a 'thing' about harness mounts and belts, I appreciate that in other parts of the
country other centres have different ideas, the only constant thing they have, is that there is no consistancy!
Pat, I can say, that there is no way that MK make/made their harness mounts for their 'Escort'/Book chassis anything like you have done (I
got my chassis late 2002). The 'bolts' did not come in centre line of the neck/spine, that is lethal (IMO), one bad whip of the neck, and it
could very well snap your spine (IMO)
The only fault I found with their harness mounts were that they were not central to the seats, ie they did not come in the centre line of each
shoulder, and if I had used them , I would have been in danger of slicing my neck, also the height was wrong, they did not meet the height requirement
required for SVA with or without the seat in place.
I did speak to MK at the time, and they told me that they were made to be used with their seats, which of course I was not using.
I was not convinced, but I do accept that there may have been a boo-boo with my chassis, and I had to rectify that issue.
Pat, can I suggest, that before you go any further, that you look at a few 'Escort' (Book) based chassis? I do not know where you live in
relation to MK or other chassis manufacturers, or indeed other 'book' locosters, but I feel that you ought to look into the mount issues
further. As I said earlier, I do not want to tell you how to build your car, but we all want you to get through the SVA but also be safe on the
road.
Rorty has made very valid points with regard to the whip=lash effect, it is a grave concern, and if you were down here, I know it would not get
through SVA, and I am sorry to say this, but the construction is no where near strong enough, or suitable.
This is all in my opinion only of course.
Fozzie
The MK chassis are done with two 40-50mm long) threaded tubes welded to the back of the square bar.
With the more recent ones having a gusset around them for added strength after a few SVA failures.
The ever helpful photo archive of Bob:
http://www.locostbuilders.co.uk/photos.php?action=showphoto&photo=in_boot1.jpg
I'm under the impression that the square top rail of an MK is slightly taller than a book car though- which helps get the 460mm I guess!
IIRC my SVA book says that you should be prepared for an accident where the pull on the belt mounts is 10G!!!
So if you weigh 80Kg (12.5st) that's 800Kg on the mount....
Just bear that in mind folks!
Cheers,
James
Thanks everyone, didn't mean to upset anyone!
I have "E" marked 4 point harnesses, but have always found the mounting points on various cars to be too far apart and they "drop"
off the shoulders so I was going to use one central mounting point for the top two "clips" of the harness.
As I am only 5'6", my seat is almost 12" from the back of the chassis so I don't think I'm in danger of catching my neck on
it.
I has originally intended to mount the tube through the chassis top rail, but was worried about weakening the top chassis rail.
So to try and "be safe" can I use one single central point mounting, welded through the top tube?
A lot of the locosts I have seen have a threaded tube (longer than mine) welded to the top of the chassis tube and reinforced behind with a small
plate - surely this won't be as strong as mine would have been welded to the back with a triangular gusset in front?
Pat...
With regard to Whiplash, I was under the impression that race regs require a raised seat back or seperate pad behind the head/helmet of a driver, to
reduce whiplash injuries and avoid any possibility of a head being trapped under a bar that might buckle if actually used in anger i.e car upside
down. Sounds like a good idea to me , and a feature I am ging to put on my car (with a removable one on the passenger side)
Another point on strength of belt mounting points, does the group think that there could be a point where the belt attchment points could be too
rigid, in that a bit of deformation in the chassis could reduce the G force transmitted to the person in a dead stop head on collision, or would the
inherent belt stretch always deal with this?
Cheers
Fred W B
I would suggest that chassis deformation of the harness mounting points would need to be thoroughly tested (if ever proven to work) and certifiable or
sva'able as an accident/impact safety feature. I think this would be well beyond the remit of any locost, though an interesting point fred.
Ned.
Just had to say that this is a very good thread. I will not be having to go through an sva but learning anything about increasing our safety and
passengers is always good.
Thanks
Dale
I think if the belts are mounted lower than your shoulder you would cause them to pull down on your spine (submarining) causing damage to shoulders
and compressing the spine I still think the rollbar crossmember is the easiest way round it.
Rescued attachment beltfitting.jpg
Fred, in racing, no doubt you are right, but we are talking road car here, the laws with regard to head pads wouldn't apply.
I think also, that you will find that our cars with the extra horizontal bar added, have only added probably less than 2 inches above chassis rail, so
no chance of head getting trapped there.And if your harnesses are properly fitted and tight, you wont be 'flung' anywhere, your
belts/harness should be doing their job!
BTW sorry if I have misread above postings, trying to do too many things at once....as usual
ATB Fozzie
There has been quite a bit of talk about racing standards (some of it by me), and I am aware Avoneer's car is not being built for racing, but I
think when safety is an issue, it pays to investigate the highest current standards.
Pat, as Foggie says, your first point of reference should be the SVA manual. I would subsequently pay your local (or wherever you intend taking your
car for its test) SVA centre and seek their views or reassurance on your proposed harness mounts.
Controlled chassis deformation is a very complex area and I wouldn't suggest anyone without extensive experience even go there. There is no need
for the harness mounting points to "give" in an accident as long as reliable harnesses or seatbelts are employed. Current seat restraints
are made from Nylon webbing which actually stretches when heavily loaded. This is by design and not a flaw.
A number of years ago some cheap harnesses made from polyester webbing (the non-stretch stuff as used in load restraints and tie-downs) came on the
market from somewhere like Taiwan. 
Even the type of thread used for stitching the webbing is critical. I received a circular from CAMS quite recently warning about some faulty harnesses
which had suffered catastrophic failure of the stitching. Good quality safety gear is really a must.
quote:
Originally posted by Rorty
Pat, as Foggie says,
Absolutely Rorty!
I totally agree with you in regard to using the highest standard of harnesses available.
Unfortunately, the SVA's requirements are not as stringent as I personally would like to see in that regard.
ATB Fozzie......(aka..foggie...lol)
quote:
Originally posted by ned
quote:
Originally posted by Rorty
Pat, as Foggie says,
who's foggie?
Not the same as the car in question, but here's an aftermarket harness bar fitted to a Porsche:
and another Porsche (Boxster):
LOLOLOL
Get some Zzzzzz's mate ya right, its late in the Antipodes...
ATB Fozzie/Foggie.....
ps Foggie IS more apt today, but Ted 'Flanders' just don't sound right......
lol sleep well rorty
Hi Guys,
Yep - very imformative thread and I'm trying to find a solution without upsetting everyone!
Beasically, I have 4 threaded inserts and eye bolts which I want to use without adding to much weight to the chassis.
I can use all four or just two (one for each side).
I can't have a horizontal bar on my cage as I have a diagonal welded in.
If I did it lke the attached pic, the only problem I could see would be the twisting force on the chassis bar, which would be there even with several
different mounting variations, but could be reinforced with bracing from this top bar down to the middle bar.
Any further suggestions/constructive critisism would be greatly appreciated as this will not only help me in the long run.
Thanks,
Pat...
That has to be better than the MK (pic from the link above):
Rescued attachment in_boot1.jpg
Pat, Have look again at my car again on page 1, I too have a diagonal in my MK roll cage!
If that is a picture (above) of the MK harness mounts, then all I can say, is, mine looked nowt like that!, but that was before the 'new'
MK came to be.
Fozzie
Hi Fozzie,
Thanks for the reply.
My hoop is already welded and there is no room for a horizontal bar - there was on my Avon and that how my belts are mounted on that car.
In the book - two ugly slugs were all that was used and this was for racing - I know times have changed, but they must have been stong enough then.
I know the newer MK chassis has changed and the inner mounts have a plate on them just like the ones in my pic above.
Is the only problem that mine are too long???
I just don't get it when this method is fine for many of the manafacturers cars and appears to be the norm.
Pat...
[Edited on 29/7/05 by Avoneer]
Hi Pat,
Yes, it can be a problem, my diagonal was already in place (part of the MK roll cage ensemble), and I had no alternative but to weld the horizontal
on.
I have looked at my old pics of the harness mounts in the early stages, and I must say that they are/were built very much stronger than the pictures
depict. In fact remarkably similar to the picture you posted (blue car).
I can assure you that if I had any doubt that they were not strong enough, or couldn't take an impact and 'roll', I would have been the
first to 'kick-up'!
As it is, I am not using 'their' harness mounts for the reasons that have been stated many times in this thread, 1, the datum point was too
short and 2, they were askew to the seats.
That is why I suggested that you actually looked hard at the way they are done, as a photo cannot give you the 'true' picture (3D).
Unfortunately mine are now panaled in, so I cannot give you any pictures from all angles.
This isn't about upsetting any of us, we all want what is best for you to get your car on the road, but safely for your sake, and also of course
for your passenger.
If we can impart our collective experiences to help you and others realize exactly what weight and force the harness mounts and belts have to endure,
and that 'life' does actually depend on how strong, and how the mounts and belts are positioned, it can only be for the good.....IMO of
course
I really hope that there are other builders/maufacturers local to you so that you can have a 'squizz' at their harness mounts
ATB Fozzie
Cheers Snoopy and everyone else for all your inout so far...
I have gone forth as follows as I think this is the best wasy forward for me and my chassis.
The eyes now sit at the correct SVA height and are long enough to screw almost to the bottom of the threaded tubes they are in.
What I am now looking for is the best way to strengthen/reinforce what I have done.
Thanks.
Pat...
Rescued attachment 1.JPG
And another pic:
Rescued attachment 2.JPG
Please excuse the Hollyoaks babes calender in the background.
Snoopy, so very glad you 'joined' in here!
I have/had NO concerns regarding strength and quality with regard to the 'Book/locost' MK mounts with the early chassis. Just, as you have
read about height/positioning
So pleased you have addressed those issues with the new locost/book chassis that you are now producing!
Is Pat/Avoneer anywhere near you?
ATB Fozzie
Hi Fozzie,
I'm not far from MK - Am I missing something?
Pat...
Pat, I was just pondering as to whether Snoopy and co would let you visit so that you could see ...in the flesh so to speak. how the harness
mounts/bolts are fitted. Sometimes I think actually seeing something you know is right, makes everything all fall into place!
I know sometimes that all of our opinions in words, can just make things...ahem....foggier....
I hope I am not being presumptious...
ATB Fozzie
ps talking of 'in the flesh', perhaps this weekend is/is not the one to go. IIRC I think they have young ladies visiting.....
Hi Fozzie,
I have been to MK on several occasions and helped a few people with their MK's.
I have also finished an Avon, and have several friends with various cars, Ginetta etc.
That's why I can't see a problem with just slugs welded to the back of the chassis tube.
If the lengthening of mine will only increase the twisting motion of the top tube, then this can easily be reinforced.
I only tack everything on my chassis and my friend (who build his own Avon chassis and has been welding and CADing structures for many years) has been
doing all my welding. I would put my life in his hands so to speak and he can't see a problem doing it the way it currently is, all be it with a
triangle gusset on the front side.
Pat...
Hi Snoopy.
Yep that's it - there will be a 1" sided triangle gusset made from 3mm plate (nicely guilotened by MK) exactly where you have drawn.
I think that will more than do the job and the only problem I can see is that in an impact, the top tube will twist - but that's what you want
isn't it if the impact is gonna be that bad.
Pat...
Snoopy - wha the hell was that all about
quote:
Originally posted by Avoneer
Cheers Snoopy and everyone else for all your inout so far...
I have gone forth as follows as I think this is the best wasy forward for me and my chassis.
Pat (Avoneer), I'm afraid you've gone and made matters even worse by your latest addition. Take a look at what you've done! You've
effectively increased the length of the lever which will make it easier for the harness to rotate that square tube and rip it out of the chassis.
I see your diagonal (which actually sits too high up from the base plate) and there's plenty of room to weld a horizontal tube in there. If
necessary, cut a small fishmouth in it to clear the bottom of the diagonal.
I agree with FoZZie; if you can, go and look at MK's latest offering and talk to them about why they have adopted it.
Hi All.
Personally, I'v never liked the idea of 4 belt mounts welded to a single cross member.
Welding them on the back face of the box section is not "good engineering practice".
How about an aditional cross member, (see pic, red lines) with the threaded bosses
welded into a plate between the two cross members, (blue lines).
This is how I'v made mine. When the top cover sheet goes on it's then covered up.
Just my 2 p's worth.
Paul G
Rescued attachment s-m-s.jpg
I'm back again.
Thought I'd better show you mine.
Rescued attachment top-s-b-mounts-s.jpg
Hi,
Rorty - many thanks for your input and experience, but I just can't see how even approx 10G of force could rip out that top bar. The following
pic shows how it is fully welded at each end with a multitude of other bars and plates coming off it at various angles.
With all the Locosts/MK's etc, on the road with slugs on the back of this bar, why have I never seen or heard of any reports of them ripping out
or twisting, even in racing?
I know a horizontal bar in the cage would be best, but I don't like the look of them and don't want one - that surely isn't the only
solution?
I can't see how what I have now done has made it worse? Fully welded, the only problem I can still see would be the twisting force, but this can
be re-enforced by tying the top bar to the middle one can it not?
After SVA, they will be made level with the top of the tube and will be almost the same as MK's then - and I know of a few cars that have had a
shunt and had no twisting of ripping out of this bar.
I fully appreciate what you are all saying and many thanks for the on-going input.
Thanks,
Pat...
Forgot the pic:
Rescued attachment bar.JPG
This is how Fisher do it on their race cars (and that's a lot different from how mine will be isn't it???):
Rescued attachment fuel_pump_01.jpg
quote:
Originally posted by Avoneer
I fully appreciate what you are all saying...
Thanks 907.
If the inserts are only welded to the plate, won't that be even worse as they will only be welded at one point on there circumference, where mine
would be welded like this and then up each side of each tube as well and at the front with the triangular gusset?
Pat...
Rorty, please can you comment on the previous pic of a racing Fury and the following pic of the Stuart Taylor Phoenix with the chassis made by
caged. Thanks. Pat...
Rescued attachment st3.jpg
Sorry Pat...... only trying to help.
If you don't like my method of counteracting the twisting force that
would be exerted on the box section cross member, then please, don't use it.
Lets face it, if you have a head on in a seven you'll probably end up under the other vehicle,
or in the event of an impact that could destroy the belt mounts, your kidneys
will be either side of your navel.
ATB Paul G
p.s. Thanks for the complement Rorty,
it's made me blush.
[Edited on 30/7/05 by 907]
Pat,
The threaded bosses on the Fury look to be welded quite securely to that square tube, but I don't get the web between them. To be of any
practical use, the web would be better if it were extended past each of the bosses. But I just wouldn't do it that way to begin with.
The Stuart Taylor Phoenix looks to me to be a right bodge! All the above IMHO; I'm sure the nice people at Stuart Taylor know what they're
doing.
Pat, there are a dozen or more ways to do this, and some dodgy examples of engineering abound (I wonder if any have been tested statically or
dynamically).
You will see many variations in cars from amateurs to commercial manufacturers, but their methods of attaching the shoulder straps to the chassis
aren't necessarily proven or the best solution. They're mostly there to meet SVA requirements and not much else.
I rode bikes for years (and rode motocross and trials) and I could have worn a cheap moulded Taiwanese helmet which met the basic safety requirements,
but I've seen what can happen to those helmets by just sliding off the roof of a car onto the ground! I wouldn't wear one of those cheapies
in a fit. I choose to look after my ugly noggin so I wore a quality hand laid glass/carbon helmet with a rating that far surpassed the required
rating. But, those damned plastic lids sell by the thousands. Go figure!
If you're happy with your harness attachments, then you go for it son!
We can only offer advice (not instructions); mine is based on years of witnessing hard impacts and roll overs on the track and some subsequent
injuries and retirements from motorsport.
Thanks.
907 - I know you were trying to help, I was just wondering what other advantages your method had apart from the twisting aspect, which I could remedy
in mine.
Rorty - the ST chassis is the one made by Caged - the guys that know more about safety than most and build all the cages for Caterham etc.
Not trying to justify anything, but if Caged think it's ok that way (which is less than mine as they don't have the web on the back and they
are welding round to round) I think it should be fine - I'm sure Caged will have tested it and worked out if it was strong enough.
Pat...
907 - Just read the second paragraph of your point and that says it all...
If you're in a crash bad enough to rip the mounts off, I'm sure there will be far worse things to worry about.
Cheers,
Pat...
And I suppose Westfield have got it all wrong to?
Rescued attachment 20020910_eyebolts_2.jpg
Hi Pat.
Glad you read that bit.
I sometimes think we on locostbuilders are guilty of tunnel vision.
We think of only one aspect of a design, and then discuss that
aspect without looking at the big picture.
I remember a few weeks ago 5th Gear crashed a Smart car (amongst others)
into a brick wall at 70 mph (remote controll). They then discussed how the
footwell area didn't collapse, and the shell more or less held its shape.
Right at the end, they then said that the driver would have died anyway,
his brain crushed against the inside of his skull.
On here we'll argue about say, a bracket thickness, 4mm? 5mm? 6mm?,
and forget it's welded to a bit of 1.5.
Let common sence prevail.
ATB Paul G
Personnaly I'm with Rorty on this one Pat. If there was anywhere I wouldn't be bothered about "adding too much weight" it would be
the harness mounts.
Please don't under engineer them.
Why are "Caged" the experts? Lots of companies make things that are not fit for purpose (not that I'm suggesting Caged do). Ask them if
they've tested their design. I'm no expert but it looks a little weak to me.
The Westie mount isn't bad remember westfield use solid bar instead of 16g for member "O", The one on the ST chassis is iffy -- so iffy
I wouldn't barge it with a touch pole.
The gusset plate on the fisher chassis is pointless it does sweet FA.
A raised SVA legal belt mounting if it is used in anger will create a direct load and torque on member "O" and as the load point is
positioned at some distance from a node it will result in member "O" being subject to shearing + torsion + bending
On my own car I used 3.5 thick 25x25 RHS for member "O" -- I actually only intended to use 2.5 mm but could get 3.5 more easily., I have a
camel hump mountings like Ned except I have only one hump the full width of the car. The rear bulkhead has additional bracing to take some of the
torsion load off member "O" and I am going to an additional tube and gusset plates similar to Paul 907 (except my welding is nothing like
as pretty)
These mods don't just strengthen the seat belt mounting but also are designed to stiffen the rear spring turrets which are an iffy area of the
book design.
[Edited on 30/7/05 by britishtrident]
So are we saying that the mounts are fine and the only problem would be the twisting force on the top tube?
(which will be greatly reduced once the mounts are cut down after SVA)
Pat...
Ok, been thinking (doesn't happen often)...
If I weld in a 19mm bar like 907's idea and then a 4" wide 3mm plate on top of the top bar and this new bar (fully seamed welded) - would I
get away with just welding appropriate nuts on the underneath of this plate?
Pat...
Well, lets put it this way Pat.
If that fails SVA then so will mine.
I have just a tiny reservation. I think the SVA chaps prefer a
threaded tube or boss to a nut, (not 100% sure) as a nut is
thinner than the diameter of the thread.
i.e. a 12mm nut is 10mm thick, 10mm nut is 8mm thick etc.
My bosses are 20mm long + 4mm plate = 24mm of thread.
ATB Paul G
Hi Paul,
If I drill through the top of the plate and insert my current 60mm threaded inserts and weld them with 5mm protruding from the top of the plate and
then weld a narrow 3mm strip across the bottom of the two tubes with the insert passing through this, that should make everyone happy shouldn't
it?
Minimum height is still just over 500mm from the seat squab, but I can always unscrew the eye a bit and put some washers under it.
Can I get away with one eye for each harness as both clips will fit on one eye?
Pat...
Rescued attachment DSCF0162.JPG
Even better.
Not sure on the one eye though.
I think they like the belts to pull in a nice straight line.
Paul G
The mounts are too close to the seat back to use one eye --- it wil tend to make the belts slip off the shoulder.
I tried it before with one eye and preferred it, but if I have to use two, is 3" apart ok?
Is everyone happy with the solution now?
Cheers,
Pat...
"It's been emotional"
Pat,
Your 'new' design looks so much better (yours is brill Paul, lovely welding), I still have concerns over the height issues (datum), if I
have understood correctly that you are planning to have your eyelets lower.....No, I do not suggest that you have your eyelets high out of the chassis
tube.
For SVA you do need threaded inserts and HT (High Tensile) eyelets or bolts.
Sorry Pat, you cannot get away with one eyelet, it is far too close to the seat.
Earlier today Marc from MNR put up a link to draft SVA manual, if you look at it, the first section 'E' does not apply to 'our'
cars, the pre-fix refers to imports, I will try to find the link.
ATB Fozzie
quote:
Originally posted by Avoneer
And I suppose Westfield have got it all wrong to?
Marcs posting:-
http://www.locostbuilders.co.uk/viewthread.php?tid=29398
Thanks Fozzie,
I'll use two eyes per harness then - no probs.
I think I'm still well within the datum point as my seat bolt to 4mm bar, not a tube like on many chassis' and my GRP seats have a low
base.
Even with the eye flush on the plate, it's still more than 500mm from the seat squab.
As the eye bolt is 2" long, it can be raised for SVA purposes and spaced out with a few washers and still have plenty of thread in the insert
which will be (now) very firmly mounted.
Pat...
Thanks Rorty.
Sorry if I sounded sarcy, it's in my nature being born and bred in Salford (Manchester)
The top of my low back seats are parallel to just under the eyes of they are flush with the new plate, so there should be no problems there.
I can now see the light at the end of the tunnell.
Pat...
Brilliant Pat, smiles all round then!
ATB Fozzie
Looks much better to me Pat, and I know sweet FA!
Right,
The top plate is stitch welded at the moment (big 3" stitches though).
The tubes protrude 10mm above the plate (but can be cut down).
The tubes have a big fat weld on the underneath of the top plate.
The small bars across the bottom of the two chassis bars are welded at each end with big fat welds.
Each tube is also welded with a big fat weld on the bottom of these bars.
Don't think it's going anywhere.
How's that people???
[Edited on 3/8/05 by Avoneer]
Rescued attachment 1.JPG
Sorry, they looked crap in colour due to the surface rust.
Pat...
Rescued attachment 2.JPG
Yup, I'd trust my life to those.
Paul G
Thanks.
Will look nice once they are cleaned up and painted/powder coated.
Pat...
First rate!
Thanks guys and for all your help.
Look really neat this way and gives me a nice flat panel to make fitting a hinged boot lid, camera mount or tonneau cover dead easy.
Pat...
Loks good Pat, but looks like an Avon now!
Well done Pat!
Excellent! good job!
ATB Fozzie
yep, i'll come for a ride in it now.
not that i wouldn't have before
tom