4 Point Roll Bar

What are the rules of the sanctioning body you're racing under?

The x brace between the main hoop supports is an extra, I don't think you're going to find too many rulebooks that require it and therefore the tubing size is unimportant.  What you will find that's required in (almost) all rulebooks is a main hoop diagonal, which you don't have.  

That said, this is a roll bar not a cage, so it all comes down to what specific clubs think of it and/or any instructors who happen to get into the car with you.  There's no right answer.

In reply to steronz :

Ok thanks.

Is it still considered to be a safe roll bar even without the diagonal? This car is mostly used on weekends and sometimes for drift events & hill climb but nothing huge. Also which type of padding do you suggest? Currently I have Aa115a OMP padding but it seems too hard and requires sealant to install.

Rollbar padding needs to be denser than you think.  Before there were specs and most padding was cheap pipe insulation I had a fairly minor hit and my helmet compressed the padding easily and made an uncomfortable noise when it struck tubing.  

In reply to Wally :

I see, I was thinking to switching for SFI Dual durometer padding.

Roll bar/cage requirements along with padding specs will be decided by what ever clubs you run with. Choose the most stringent set of rules and  build to that and you will have better equipment than the the other groups required.  Typically anything that passes SCCA  rules will be fine any where.

RHD car...not in North America? Rules may be different where you live and the no-diagonal may be accepted practice.

In reply to Jvella36 :

I really can't say if running without a diagonal is "safe," as I'm not a structural engineer and I don't know the loads involved.  Obviously the diagonal is going to provide some solid triangulation right behind your head and help prevent the main hoop from turning into a squished parallelogram, but is that going to be the primary way the main hoop fails?  I can't say.  Lacking a rule book, it's going to come down to what you find safe, the organization finds safe, and any instructors/passengers.

As others have said, safety tends to be an "all or nothing" system.  With a fixed back bucket and harnesses, your body is going to be held upright in the event of a rollover, so you don't want the roof compressing down on you.  With a stock seat and a 3 point belt, your body is free to skew out of the way in the event of a roof compression.  So once you go fixed-back then you need strong rollover protection, and without that you're better off sticking with the factory system.  I still have the 3 point belts in my Miata in addition to 6 point harnesses and I swap between the stock seats and fixed back buckets for track events.  That's the closest I could figure out do actually having a dual-use car.

Likewise with padding, once you have a roll bar driving without a helmet becomes dangerous, most padding is designed to be impacted with a helmet and would do nothing to prevent a head injury without one.  I too run the dual durometer padding which I don't consider "safe," just "better than nothing."

At the end of the day I think we all accept some level of risk.  There's certainly a lot of people who say "I would never get in a car without X," and X is different for everyone -- not a lot of DE cars have fire supression systems, for instance.  Just keep in mind what others have said about how the components work together and use your best judgement.

Jvella36 said:

In reply to Wally :

I see, I was thinking to switching for SFI Dual durometer padding.

A friendly reminder because it seems to always be overlooked...........it's still designed for a helmeted head, not your bare noggin.

In reply to steronz :

Thank you very much for the detailed answer, well like I said this car is mostly used on weekends for a regular drive and also for some fun events, so I think the level of risk is pretty balanced.