Harness anchorage points

[Johno]

Need some advice on this topic.
I know most people are mounting their top anchorage point for their harness off their roll bar tube but I plan to mount mine from the top of the seat rail box section the same height as the mounting plate for the roll bar base plates.
Iv'e tried to keep my seat as low as possible and the distance from the the seat base to the top rail is more than the 450mm as specified in the IVA manual.
The area I'm struggling with is this... I'm using a GRP seat with holes through the top for the harness. Correct me if I'm wrong but as long as the harness does not pull down on the seat (this then becomes a load bearing structure) this will be OK but on a post somewhere I've read "as long as the anchorage point is not lower than shoulder heigth it will be fine".
So what if the examiner is a different height to me and the top anchorage point is either above or below shoulder height without touching the seat which is acceptable....
I plan to make machined spacers if required to clear the seat and use eye bolts as Westfield.

Sorry not very good at explaining myself but I hope you get the jist...

[alga]

Mounting them on the chassis will make it hard to satisfy the requirement of >45 cm above the reference brick on the seat (IVA 31.16). The seat will really have to be low and thin to pass this.

As for the different size of the examiner, I think I've read they check the belts with you in the seat.

[Johno]

Originally Posted by alga

Mounting them on the chassis will make it hard to satisfy the requirement of >45 cm above the reference brick on the seat (IVA 31.16). The seat will really have to be low and thin to pass this.

As for the different size of the examiner, I think I've read they check the belts with you in the seat.

Just to clarify this rectangular piece of 136x53mm does that go all the way across the seat including its sides (I have "Kitparts Direct" grp seats with raised sides) or from the lowest point of the seat as the manual is a bit vague...

[Davidbolam]

Why don't you make your own tool to check the heights etc. I remember watching either a kit car is born or a race car is born and they showed the tool as the car was tested and its quite rudimentary. All you would need is a bit of string some wood and a protractor.

David

[Johno]

Originally Posted by Davidbolam

Why don't you make your own tool to check the heights etc. I remember watching either a kit car is born or a race car is born and they showed the tool as the car was tested and its quite rudimentary. All you would need is a bit of string some wood and a protractor.

David

Hi David..
I was going to press up a piece of ally to the required size to sit on the seat but obviously the wider I make it the higher it sits on the seat.

ps.. did you get your template????

[alga]

Originally Posted by Johno

Just to clarify this rectangular piece of 136x53mm does that go all the way across the seat including its sides (I have "Kitparts Direct" grp seats with raised sides) or from the lowest point of the seat as the manual is a bit vague...

I think it's the lowest point, it would not make sense otherwise.

I wonder where does the 136x53 size come from... It must be some everyday object the testers used as the source of a reference point.... An offcut of some timber, a box of their favourite biscuits, or something.

[Johno]

Originally Posted by alga

I think it's the lowest point, it would not make sense otherwise.

I wonder where does the 136x53 size come from... It must be some everyday object the testers used as the source of a reference point.... An offcut of some timber, a box of their favourite biscuits, or something.

Hi Alga,
Measuring from the base of the seat it seems I can acheive a height greater than 45cm including the 53mm but is it Ok for the harness to anchorage point to be lower than your shoulder...
I could possibly make a spacer from solid round bar and move the anchorage point higher if needed but would this be neccessary if above 45cm as stated??

[snapper]

To clarify
The block 136x53 is put longways with one end pushed to touch the back rest
You then measure from the front top edge of the block vertically up 450mm
Then draw a horizontal line back, your belt mounts should be at this height or higher, its prudent to add a few mm to this minimum height.
The block longways achieves 2 aims
1. Makes the horizontal and vertical measurment point transect the center of the top of the theoretical shoulder
2. Takes into account any rake on the seat base (some have more rake than others)