Rollover Protection

[rms]

Hi, I have a couple of questions about rollover protection.

1) Section 2.4(8) off the standard States:

"A roll-cage may be positioned within the B-Zone of a low volume
vehicle occupant cell, provided that
(a) the vehicle is not a modified production Class MA, with unitary
body construction, which has a permanent roof structure; and
(b) the requirements of 2.4(9) are met."

Am I correct in understanding that this allows a convertible street car such as a Mazda MX5 to be certified legally with a 'full' roll cage, without requiring it to be MSNZ homologated and having an MSNZ Authority Card and race harness?

2) Where the standard states:

"all sections of a roll-bar or a roll-cage positioned adjacent to any
A-Zone must be covered in a high density energy absorbing
material which:"

Is the 'high density energy absorbing material' able to protrude into the A-zone or would this be classified as part of the roll cage structure?

I'm asking this more out of curiosity than for any practical purpose.

Thanks

[Dan]

You are right, an MX5 can have a roll cage, as long as none of it is in the A-Zone. The Hobby Car Manual confirms this:

"In the hobby car world, this means that you can have a roll-cage in open or convertible vehicles; or vehicles with a roof structure not designed for rollover protection such as those with a fibreglass body.
Also, off-road-type 4WD vehicles, and any vehicles with a separate body/chassis can all have a roll-cage.
Don’t forget though, the ‘A-zone’ clear space requirements still apply in all cases."

If you have a look at the standard again you'll see that the A-zone is actually quite small, especially in width, so you wouldn't want any part of the cage near to it. Therefore to ensure adequate clearance the cage padding material should be considered part of the cage and should not be in the A-zone.

There are also other requirements:
A low volume vehicle fitted with a roll-bar or a roll-cage within the ‘B-zone’, must have:
(a) a head restraint fitted to provide protection for each occupant where a roll-bar or roll-cage section exists immediately behind a seat; and
(b) no unprotected hard or sharp bracketry positioned where it would be likely to be contacted by an occupant in the event of an impact or roll-over; and
(c) all sections of a roll-bar or a roll-cage positioned adjacent to any A-Zone covered in a high-density energy-absorbing material which meets SFI specification 45.1 or another equivalent motor sporting specification; and is not less than 15 mm (5/8”) in thickness in the area facing the occupant cell.

Finally, while a cage in an MX5 might not require an MSNZ authority card, it does require LVV certification.

Dan