Ive had a read now i found my manual it states the threaded section should pass all the way through the tube !

Bit overkill really the belts that saved my life last time were bolted into original mini seatbelt mounts ie captive nut on a small spreader plate ! Very similar to the design of the lower seatbelt anchors in the book

seat belts
 

after reading all the posts i wanted to do it on the safe side and dropped the 7/16 unf bosses all the way trough the cross brace and welded top and bottom if you use tapped bosses rather than through holes toy can use eyes or bolts

Apologies for the slow reply :o

My upper mounts are as "Snapper" has said, a thick walled fully threaded boss that goes all the way thru the roll bar cross brace & welded top & bottom then the eyelets/hoops for the snap lock of the harness mount clipped onto them.

Just a note.......as it is possible to unclip the harness quite easily from the eyelets I,ve fitted some very small split pins thru a hole that is already there in the snap fitting so that they can,t be easily unclipped.

cheers
andy

Whats the opinion on the fixing bolt's,will they need to show through the boss or will they accept evidence of loctite etc.

I beleive they need to see evidence of the bolt all the way through

The bolt does not need to project all the way through. Loctite is a suitable securing method. Gus's car went through IVA like this without question.

Gonna throw in another re this issue ....I have turned down some 12mm nuts just to take off the corners, then I mounted these while attached to the a long bolt into holes in my cross brace so each boss was half in and half out of the thickness of the cross brace tubing, then welded them up top and underneath then when cool I removed the bolt.......so my threaded section does not go all the way through.......does this mean it would fail or would it be enough and if not could I use a long bolt instead with a nyloc on the bottom,
Failing all else I could drill them out and put a full thread length boss in, don't want to do that tho.......any thoughts peeps???

Probably be assesed on it's merits as to if it's fit for the use it is being put to.

If that makes any sense,it is down to the tester on the day.

It was mentioned to me by a tester that he would hope that a seat belt mounting would be strong enough to lift the car up by.