Seat belt mount heght
 

Just read the IVA manual and can't find a reference to the height and position of the upper harness mounts. I am sure someone (Ash?) said the inspector paid close attention to this point but I can't find any reference. I am ready to fit my cross member but don't want to weld it in the wrong place so any guidance would be very welcome.
Thanks in advance,
Enoch.

I think it depends on the holes in the seats. I'm sure someone with more knowledge will be along shortley.

If you look in the index under seat belts you`ll find a diagram about the height similar to the one about how high the seat backs have to be regarding head rests & so on. It`s a sideways on drawing showing their measuring block sat on the seat base. Dennis

I seem to remember reading about that in the manual quite some time ago .... A minimum height of 400mm above the seat datum point is in my mind for some reason :confused: :confused:

I had another read the other week & could't find that section again :rolleyes:

Best double check first .... As said, tis only a measurment floating about in my head & all of you folk know how sick my mind is !!?? :o

I`ve just checked and it`s in Section 31 seat belts on page 3 of 8, it must be 450mm above the ref point, but please read about the ref point as it doesn`t just mean 450mm high, there is a diagram showing you how to determine the ref point. Cheers, Dennis

Hmmm, my downloaded copy of the manual does not have a section 31, the only section it has that has anything to do with seatbelts is section 19 and it has no picture or mention of a reference point. Starting to think I have a dodgy download, will get another from the Vosa site.
The only diagram I have of the seat shows the headrest height at 753mm above the seat squab.
Thanks for the replies chaps.

Just downloaded a new copy, it is indeed 450 above reference point. There is no requirement for distance between upper fixings but there is for lower fixings which have to be between 350 and 500mm apart. My upper fixings will be about 75-100mm above the minimum so I should be fine. Happy days:)

Glad I am not the only one !!

I thought I was going off my trolley, Knowing I had read that section & then unable to find it again for another read :confused:

Probably reading an online version at the time, meethinks it best that I download a new copy as well :o

My memory was 50mm out .... That's about parr for the course with me .... My mental tape measure needs replacing :D :D

Hi, before you weld anything!
there is a dimension for width of the top mount from the centreline of the seat.
not sure if it only applies to a lap/diagonal belt or includes harnesses too
gonna have a quick scan of the regs now
Ray:)

Hi Ray, I couldn't see anything, only a dimension for the bottom mounts.
Let us konow if you find otherwise.
Cheers

Hi, section 31 page 2 no. 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)."
knew id seen something somewhere.
I read it as only applying to normal seat belts and not harnesses but ive spaced mine accordingly as i may use some ordinary belts or harnesses.
so ive put in two top mounts per side and may put an extra one near the floor below the top mount so i can use an inertia real belt as i find harnesses a pain to use
anyway there it is
hope it helps
Ray:)

Hi Ray, that is for a "normal" seat belt with a diagonal strap that goes from (on driver's side) right shoulder to left hip, harnesses are not diagonal belts. I was quite surprised that there was not a requirement for spacing of upper mounts when there is one for lower mounts. I guess I will just do mine so they are comfortable. Thanks for your responses and for taking the time to look it up.

The main thing he will check Dave is the the upper mounts are not lower than your shoulders so that they do not go up from the mounts to pass over your shoulders. They need to be level or above your shoulders. The strength of the brackets and bolts, plus that when your belts are tight you can release the catch and comfortably remove your arms / shoulders from the belt without slackening them off, he will try this himself a few times. Stick with the industry standard 7/16 unf 8.8 grade bolts and nuts (should be marked on the bolt) just to be sure.

Maybe we'll get another first time pass.......:)

Regards...AndyH

so you cant take the strap over the roll bar and secure it to a point lower down the chassis, it has to be on the rolll bar?

Thanks Spud. I have made mine so that they are higher than my shoulders, I guess I have to hope that the tester isn't 6ft7 tall:D

I think you'll find you can, the roll bar becomes the "effective seat belt mount" for the mounting point height measurement.
The real mounting points should of course be upto standard and the bar the belts loop over will be assesed for strength "as if they were mounted there" as in the event off a crash all the load would be consentrated on the mounting and the bar.
I did this at SVA, any retractable belt system uses this method as the mechanism is usually lower than the place the belt retracts into.
IVA has not changed the requirements from the SVA from what I have read.

so if you put them where the book specifies they would be wrong?
The reason I ask is because i haven't decided what seats to get yet but want to start making the roll bar soon.
I was going to make it like ash has done, but i'm unsure of the height of the cross brace and the hole spacings for the bosses to be welded in

Hi James,

I have just finished my roll bar / harness mounting & have also done similar to Ash,s build, have a look at the thread titled "Hi All" in the "off subject" section, there is a photo showing my roll bar/harness mounting position...........if this is similar to how you intend doing yours then I can give you the measurements I used .

cheers
andy

Yes andy that's how i was gonna do it but maybe with a smaller diameter cross bar, yours looks really fat?

:D makes up for me being a skinny wotsit lol.

it certainly is very thick walled I must admit:)

let me know if you would like the dimensions etc.

cheers
andy

Dimensions would be good thanks:)

no problem, i,ll post the dimensions on this thread tomorrow morning ( car not at home).:)

cheers
andy

sorry for the delay.......

the bottom edge of the cross bar is 8cm above CP3 CP4.

The first harness mount is 6cm(to center of hole) in from the upright of the roll bar, then an 11.5cm space to the center of the next harness mount center.

Both sides are set at equal dimensions.

Tho please be aware the position of the harness mounts will be dictated to by the seats you use etc.

hope this helps. :)

cheers
andy

I have reread this topic and feel that we need to get the seat belt rules clear and made sticky.
On rereading the thread it is clear that some people are posting answers that just are not correct or are posting hearsay as truth.
I have been involved in a lot of builds (still am) and have been at 2 SVA's and 1 IVA all first time passes so I have gained some experience and knowledge and have had tests like the seatbelt mountings explained yo me by the tester whilst he conducted the test.
You cannot set the seat belt upper mounting point without the seats fitted, you can guestimate this to a certain extent.
First to find the upper seat belt minimum height cut a block of wood 136mm long and 53mm thick, place the block on the seat base longways and push it back so one end touches the seat back. From the front top edge
Measure straight up 450mm, use a plumb bob or spirit level, Mark the 450mm height, the using string or spirit level run backwards at 90degs to where you would like to mount the seat belts ( or the bar the belts will run over) add a few more mm to put it safely higher.
To clarify the minimum upper seat belt mounting height wil be seat and seat runner thickness + 53mm + 450mm.
At least 550mm from the floor I would think.
I hope this clears things up.
It worries me that people will search threads in the future and confuse speculation with fact and fail.

I think "Snapper" has raised a very good point indeed.

Whilst I,m personally always happy to give info from my own build to be used as a guide/suggestion etc I would hope any builder would check the IVA regs/rules etc to ensure their own build is within the requirements of the IVA regulations.
My apologies if any info I have given is misleading or incorrect to anyones own build, but as there are so many possible differences within each build ( such as seats used, height of runners etc) please take the measurements that I have given as nothing more than how I have built my own car & not as the way to do it on all builds, due to so many possible deviations as mentioned.

Well said "Snapper" :)

cheers
andy