There was a required spec in SVA for roll bay size and thickness so i assume it still applies for IVA

I can't find anything in the IVA regarding this.

Well, not the thickness, it only really mentions that the roll bar will be subject to testing for exterior projections

as far as the iva is concerned you dont even have to have a roll bar period. if you hae one they just check it for sharp edges

Thanks Ash that was a question I was going to ask
Ray:)
p.s. id like a double hoop but not like the one above im waiting till near the end of my build to do the roll bar if i put one on

A question,assuming the bar is not fitted they cant test it obviously,does the same apply to a passenger seat and it's seat belt for IVA purposes.
In an MOT if it's not fitted you cant test it ie seat missing/belt missing,Someone who has read and digested the manual will know the answer.
On the suject of roll bars, I rightly or wrongly bored the center of the plates for the bar to go through to give more of a surface to weld to,thoughts or comments ?

Cheers

There's nothing wrong in cutting a hole in the mounting plate as long as you have welded it inside and out so that it does'nt cut through the shock mount plate. I personaly would have ground a 45 deg 1.5-2mm weld prep (as you should be doing with all your thicker plates!) all around the edge and welded solid with about 160amps. Reguardless of what any body says on here by the time the rollbar has hit the ground hard enough to punch a 40-50mm hole through the 3mm plate the 'I told you so' will be the least of your problems.

It will be welded in and out and it's 5mm not 3 and has a chamfer on inner and outer edges of the hole (I started my working career as an apprentice welder in a shipyard )the rear bars may end up on the diff cage for more strength.
All thought's and comments are gratefully recieved.

And while I am in here can one of you nice gents tell me what size or diameter of the the slots in the rack support plates are.

Thanks.

Talon's point about what the rollover bar is atached to is a good one, and nobody seems to be picking up on it. It's all very well having a really strong bar made with all the best and most expensive materials, but look at what it is attached to!

Safety maybe ought to be priceless, but it isn't. We all balance our safety with other considerations every day,and safety frequently loses out to convenience etc. And if we really really wanted to be really safe, would we be driving this kind of car anyway?

I get your point,Stay safe, stay at home and don't drive at all.

Heck of a lot of accidents happen in the home, mind!