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MG Midget and Sprite Technical - shoulder harness attach point

attaching my two belts over my shoulder to a point on top of the axle area seemed like a good idea at first but on heavy braking I can feel my spine compressing. Would bolting a bar across the top of the higher wheel well be a better idea? Maybe something welded to my roll bar? any thoughs out there? Thanks in advance,---Bob C in KS
chamberlain Bob

I would imagine that the roll bar would be too high for safety in many ways and would possibly be a problem with neck trauma.

Have you got sports seats fitted?

What sort of harness is it?
rachmacb

as the belts go over the shoulder and then drop to the mounting, the angle should ideally be around 10 to 20 degrees. A crossbar welded to the cage or rollover bar is often used in competition cars.
David Smith

Is your roll bar a full width one? I've noticed in the past that some available in America are sort of half-width ones? So, perhaps that would affect the fitting!
rachmacb

Bob,
If you canloop your belts over the roll bar or attach another bar, do it. The belt mounting point, or the point at which it goes over the bar shold ideally be at shoulder level. Below will compress your spine and possibly cause injury. At or slightly above shoulder level is ideal.
Tim Michnay

This is what I have done. Any thoughts?


Neil (K series)

Do they have those sorts of rollbars in the States? I have only seen halfwidth ones?
rachmacb

Bob, from what I've read the shoulder belts should be anchored no more than 3" below shoulder height to prevent spinal compression as you describe. If you have a roll bar fitted most weld a cross bar on that and anchor the belts to that point. On my car the cross bar is mounted between the main hoop and the diagonal brace bar.


Bill Young

Hi neil

IMO you should weld a 2-3" strip in the middle of the bar to the shelf/boot joint below and to the rear.

That's not the result of any analysis, nor knowledge of MOT; it seems the bar should have more support.

A
Anthony Cutler

You may well be right Ant. I'll update you soon.
Neil (K series)

"At or slightly above shoulder level is ideal."
sorry but I disagree Tim; slightly below shoulder height is the recommendation, especially if you are going to wear a HANS device.
David Smith

Wow guys!

Im a bit shocked as im already negotiating with Quickfit-seatbelts UK for two 3point-harnesses.
Like Bob i was planning to fit them on top of the rearshelf just inside the boot/trunk.


Arie de Best

And I've already welded the fittings in the same place ;-(
graeme jackson

Here is the drawing of what i had in mind.

Mind you i dont have a roll bar to attache it too and i planned a retractor on it aswell to give some manouvrebility in the car when the harness is on.
I planned to have the harness run arround the headrest "legs" instead of inbetween the two "legs".


So no rollbar and i have a hood that needs to be folded up as well.

I cant have mine on shoulder hight as my shoulders are higher then my seatback(mgf but still not as high as my shoulders, i would have to remove the headrest with options of other injuries(wiplash)


Any advice welcome please before i defenetly order them.


Arie de Best

Arie, while you can run a single diagonal belt from a low rear mounting without problems that's because when the belt tends to compress your shoulder the other shoulder is unrestrained and your body can twist to absorb the load. Once both shoulders are restrained then the only thing left ot absorb the load is compression of the spine. If you're running a 4 point harness with twin shoulder straps the rear mounting shouldn't be more than about 3" below shoulder height. That's still possible to do and still have a hood that folds. You'll have to add a support bar across the rear of the cockpit to anchor the belts on. It doesn't need to be any higher than the point necessary for the belts to work best, just make sure it's built of suitable material and well braced. The entire roll bar in my car while not high enough for competition still fits under the hood and the hood can still fold well. I did have to change my method of folding it though to clear the rear support bars, but again no problems with the hood in over 10 years now.
Bill Young

Have you changed the level of your hood Arie - coz most rollbars do fit under - but, if you can fix a bar across the back then that may possibly be high enough - however, if your shoulders are alot higher than the back of the seat - it would perhaps not be so good.
rachmacb

Hmm, time to do some reall messurements of how much my shoulders stick out of the top of the seatback.

My hood level still is the same but the back of my seats are as much to the back as possible as i like to drive in that position.
Therefore the seatbacks are almost on the wheelarch and hardly leaving enough room for the bars to be placed next to the seats.
I also want the rollbarr behind the headrest so if anything happens my head is be held by the headrest on doesnt slam in to the top of the rollbar.

Thanks Bill and Rache

I must say im not very keen of having a bar in the rear for just the seatbelts.

On the photo you can see how far back the seatbacks are.


Arie de Best

MGA & some early MGB shoulder straps were attached directly to the top of the tonneau panel. I think early Spridgets were like MGA, not sure - two chrome acorn nuts sticking up each side, dealer installed option. Later factory fitted anchors on wheel arch tops for Spridget, or perhaps they were always there and "our" dealers used the old MGA method. Tonneau top seems the best place available other than on roll bar equipped cars. The MGB ones had quick release spring fasteners so you could fold the top down, then reattach the belts. They didn't keep falling off your shoulder like the ones anchored on the wheel arches. Early Bs without belts have plastic screw caps in the bolt holes; don't know when this started/stopped. These appear in the 71-74 Owner's Manual as "early cars only", but the earlier book shows wheel arch side two stud mounts, my late 65 car has the wheel arch anchors.

FRM
FR Millmore

Arie, I understand about not wanting to install a bar for the belts in that nice interior, but if you want to use that type of seat belt then to be safe and protect yourself against injury in the event of an incident then you don't have a lot of other options. Mounting any higher under the rear deck only will get in the way of the hood when it folds, a problem those of us with MGAs have to live with, but fortunately we don't have the permanently fitted hood like you and I do with our midgets. You can always fit the cross bar between the rear angle supports for a roll bar to get them back far enough to clear the seats similar to what I drew here.


Bill Young

I'm not so sure that full harness belts without a roll over bar is such a good idea, at least when you have diagonal belts you are able to duck down in the unlikely event of a roll - full harnesses keep you in place in the seat even when there's no space for your noggin when the screen collapses in...
James Bilsland

Hmmmm - after seeing your diagrams and the angle of your seat, I think perhaps you should ask yourself WHY you want the harness? Aside from being almost horizontal in your driving position, and the over-height of your upper body above the seats, then I'm not sure how you can fit it safely, without putting an extra bar in - and, even then, the other angles aren't so efficient.

I would also be a tad concerned, like James, that you would be held in a rather dangerous position should you be in an accident/roll.

Although - perhaps you can just slide down a bit further in the seat - after all, if you keep it well cleaned, and with the slant-back on the back - you should just slip! It might mean bending your legs into a position that a contortionist would be jealous of though! (Or, perhaps you're really just made of paper, and this is just an extension of your origami skills ... ;)!)
rachmacb

Does the belt have to be bolted to the (new) horizontal bar on the roll cage or can it still be bolted to the new fittings welded into the top of the axle tunnel? I'm thinking maybe the belt could then just be routed over the horizontal bar to gain the required height.
graeme jackson

Hmmm, this is trickyer then i thought...

I now know my shoulderhight in the seats are halfway on the headrests.
So yeah from there to the highest point on the rearshelf (at bottom of rearpanel) is pretty steep, 40 to 45 degree angle.

Ive read the Daniel Stapleton Spridget HPmanual.
It says to keep the angle shoulderstraps as close to zero as possible.

The original wheelarch beltpoint is also much to low for the taller spridgetowners.

Indeed as several of you warn a midget without a Rollbar is dangerous when it flips on its head.
In that case a seatbelt is a certain death, even with just a rollbar the ods are low.
A full cage is the only thing safe for that.

But then there is the debate if to wear a seatbelt at all and if you have a better chance of surviving if being thrown out of the car insted.

As front to rear crashes happen the most i gues i will be safer with seatbelts on eventhough i have the US padded safety dash in my midget(if I get past the steering wheel safely that is). :)

I think i will go on ordering the 3-point harness and see what i can do when i get to designing the rollbar.
The rollbar: has to be functional BUT also fitting in the design of the midget = looking nice/original.

You never finish your spridget dontya, always something to improve... thats why i love these cars!! :)




Arie de Best

Interesting reading all of the different comments. A couple of my random thoughts-

Neil K- I would definitely put a reinforcement bar behind your seats. If you were to be involved in a crash, the seats are not meant to absorb any vertical loading as would be exerted on them in a crash. I worked at a crash test center for over 10 years and have seen it happen. Belts were mounted on the floor right behind the seat, a racing seat with belt slots IIRC, and the seat buckled under load.

As far as mounting points, at shoulder level is best. With a HANS, you can go slightly below due to the design and how it works. It's amazing how much belts stretch under load. I've seen video of a 100G sled test and the belts stretch out about 6-8 inches.

Here's a video I found on Youtube. I was looking for the one from wherer I used to work, but I couldn't find it.

http://www.youtube.com/watch?v=0RinuSRqMaM&feature=related
Tim Michnay

This thread was discussed between 15/02/2010 and 20/02/2010

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