Seatbelt anchor points

[TheArf]

Hi Guys just a quick question, is there any reason why when you fit the seatbelt anchor points they have to be in the vertical plain. I went to Loton Park hill climb at the weekend and I noticed that a lot of the competitors have them fitted horizontally, thus making the harness lie in the same orientation as the anchors and pulling in a straight line.
So my plan is to make stepped anchor points fitted through the actual cross member of the rollbar with a shoulder on them and fit them in from the rear of the car before welding and them in solid.

[jps]

Originally Posted by TheArf

Hi Guys just a quick question, is there any reason why when you fit the seatbelt anchor points they have to be in the vertical plain. I went to Loton Park hill climb at the weekend and I noticed that a lot of the competitors have them fitted horizontally, thus making the harness lie in the same orientation as the anchors and pulling in a straight line.
So my plan is to make stepped anchor points fitted through the actual cross member of the rollbar with a shoulder on them and fit them in from the rear of the car before welding and them in solid.

I'd need to see a picture to understand what you mean!

Do you mean the lower mounts (lap belt) or the upper mounts (shoulder belts)?

[TheArf]

Shoulder height hence reference to the rollbar cross member

Arfon

[Stot]

I think you need to look at it from the point of a frontal impact of the kind you get on the road rather than how they lay when unstressed. The belts are going to be stressed in a forward motion and its at that time you want the bolts be acting in shear, hence being vertical.

Cheers
Stot

[TheArf]

The ones that I saw at the weekend where fitted to a westfield that was entered into the hill climbing

the arf

[jps]

Originally Posted by TheArf

Shoulder height hence reference to the rollbar cross member

Arfon

the bit that confused me was the ' belts in the same orientation as the anchor', surely they are with the book setup...?

I get Stots point but wonder if it makes any difference, either way in the event of an impact the force is basically trying to rip the head off the securing bolt / tear the belt anchor plate / etc?

[TheArf]

Wish I knew how to draw pictures on here, right the standard way to insert the bushes through the cross member is to insert them from the top and then weld them in, this then has the harness coming off them at a 90 deg. angle. Are you with me so far, now instead of inserting them in the standard orientation, drill the holes 90 deg's to the standard orientation so that they run front to back and then insert the anchor bushes ready for welding.
I hope this makes what I am trying to describe clearer

Arfon

[Stot]

You mean like the attached looking from the front.

I'm pretty sure seat belt bolts are designed to work in shear. If you think about it the threaded insert is likely mild steel in most cases. I would have thought the threads will strip out of them in tension long before the graded bolt would have snapped in shear.

Cheers
Stot

[jps]

Originally Posted by TheArf

Wish I knew how to draw pictures on here, right the standard way to insert the bushes through the cross member is to insert them from the top and then weld them in, this then has the harness coming off them at a 90 deg. angle. Are you with me so far, now instead of inserting them in the standard orientation, drill the holes 90 deg's to the standard orientation so that they run front to back and then insert the anchor bushes ready for welding.
I hope this makes what I am trying to describe clearer

Arfon

right. gotcha. makes perfect sense. I did wonder like what Stot said, ie the threads might strip but 7/16 is fairly coarse so I do wonder whether that'd be an issue.

Sylvain, my dad tells me clip in belts are usually for things like rally car applications, where it is sometimes necessary to get into the back, e.g. to get the spare wheel out, but the belts get in the way, because they secure onto the roll cage or in the rear bulkhead somewhere... no idea if they are iva ok or not.

Arfon, I can see how your solution would work with clip in belts, still think it wouldn't look as good with the non clip type...