Help pleasE- seatbelt mounting points

[dubber91]

Hi all, kid way through a custom car build and I could do with some help regarding the correct (read IVA) way of mounting my 4 point harnesses.

The car is mid-engined, with a transaxle behind the engine. As a result, there is not a great deal of room between the back of the seats and the engine (or firewall, when it's built).

I designed the seat belts to loop over a horizontal bar running between the rool hoop uprights, and then for the harnesses to be mounted to the chassis close to the floor/ back of the seat. See the pictures.

My concern is that if I mount the belts beneath the horizontal bar that they loop over, they are very close to the motor. I can fab up a belt cover, but there is the alternator (not shown) on the passenger side that would probably be very close.

Other than this, I can mount the belts slightly forward of the horizontal bar, closer to the seat, see other pic. Would this be IVA ok?

Also, would you mount the eyelets for clip-on harnesses in direct tension or in sheer? I.e. To the side of the chassis rail or the top?

Many thanks

Steve

[AdiT]

Not sure about wether the belts goingover the crass brace would be acceptable but... As you'll have to have a bulkhead/firewall between the engine/passenger compartments to pass IVA, the engine proximity to the belts shouldn't be an issue.

Have you got a copy of the IVA manual. It's a bit long-winded, but without applying it to all aspects of te build as you go, you'll stand little chance of passing.

[dubber91]

I was told it was acceptable to put the belt over the rail - Its the only way i could get the angle required to the rear of the seat with the engine where it is....

Any thoughts on whether the eyelets should be in sheer or in direct strain?

[CrutyRammers]

It's fine looping them over the bar, but be aware that the bar will become a load bearing point - it needs to be a bit higher than the holes in the seats (so that the belt doesn't transmit any force to the seat). What you don't want is for the belt to be bearing on the seat holes themselves (so - if the seat holes are higher than the bar, the belt would loop up and over the seat holes, then the seat becomes a load bearing point). Basically everything the belt will pull on in an accident has to be strong enough to take it.

For the mounting bolts, I'd do tension personally, but people seem to do both tension and sheer with no issues, so as long as they're proper seat belt bolts they should be fine.
I wouldn't fancy having it so close to the motor though! On the dax there are big threaded bushings welded onto the bottom of the crossbar, the bolts screw into those, and the belts loop up and over the crossbar, might be an idea?

[dubber91]

thanks guys,

I Thought IVA stated that the rear mounting point had to be 10 degrees below the eyelets on the seat?

I think i'll mount the belts to the top of the tube; just not sure which tube now!

[CrutyRammers]

dubber91 said:

thanks guys,

I Thought IVA stated that the rear mounting point had to be 10 degrees below the eyelets on the seat?

I think i'll mount the belts to the top of the tube; just not sure which tube now!

Nope, never heard that one. But check in the manual if in doubt.

[AdiT]

They def' have to slope down to the seat holes. They had a spirit level on mine to check. If they slope up then the seat is considered structural and you'd have to provide evidence that it was up to the job. There have been some pass that shouldn't but why risk it (and £90 retest fee)