Roll bar / cage in a MC class 4x4 unibody construction

[kbushnz]

Hi Team

Had a search but no definitive answer.
I have a MC class 4x4..... It is of a Unibody construction. 1998 vintage... 
The way I read the VIRM as it is a MC class I can add roll protection as long as it doesn't effect the interior impact zone rule of occupants.
And I wont need LVVTA Cert....
Is that correct?

If that's right what spec can I use to fit / manufacture it so I dont compromise the unibody construction...
I assume something from the motor sport side rather than 4x4 side as most 4x4's are chassis / body construction...

Please advise..

Cheers
Calvin

[Chris]

Mar 12, 2024 19:28:37 GMT 12 kbushnz said:

Hi Team

Had a search but no definitive answer.
I have a MC class 4x4..... It is of a Unibody construction. 1998 vintage... 
The way I read the VIRM as it is a MC class I can add roll protection as long as it doesn't effect the interior impact zone rule of occupants.
And I wont need LVVTA Cert....
Is that correct?

If that's right what spec can I use to fit / manufacture it so I dont compromise the unibody construction...
I assume something from the motor sport side rather than 4x4 side as most 4x4's are chassis / body construction...

Please advise..

Cheers
Calvin

Hi Calvin

Yes, you can add roll protection to an MC class vehicle, but it can only be in the B-zone and C-zone (the entirety of the structure must stay out of the A-zone) 
The method to define A, B and C zones is in the interior equipment chapter (16) of the Car Construction Manual, which you can download here for free.

In the same chapter there are the other requirements that the roll protection must meet in 16.14. (head restraints, padding etc, etc)

As for the spec, we do not assess a cages ability to withstand a rollover, our requirements only relate to the interior impact aspect. In theory you could make a cage out of exhaust tubing, providing it met all of our interior impact requirements. But to make a cage that functionally does what a rollcage should do, I would suggest following Motorsport NZ homologation requirements.

Hope that helps

Chris

[kbushnz]

Thankyou Chris for your reply..... 
Its what I was thinking and you have confirmed that.
Time to play with with ideas for a cage....
Cheers