Discuss Legality of Door Bars

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SkilletKid
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Discuss Legality of Door Bars

Post by SkilletKid » Wed Jul 31, 2013 1:38 pm

Just thought I'd get this going as a reference for those who are looking at 1/2 cages or "3/4" cages with door bars. Would be good for the more knowledgeable members to give their thoughts on how hard it would be to get a cert for them, or if needed, MSNZ homologation.

I was really interested in this particular design from Blackbird Fabworx in the US.

He has done a design that doesn't need gutting of the door (can't find that photo) but those will definitely need a change to bucket seats (a fiarly thin seat I assume).
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BRM
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Post by BRM » Wed Jul 31, 2013 1:57 pm

Chris and I were talking about this the other day.

Pretty sure..
Because its forward of the seating position, you'll need cert / log book..
Kinda, treat it as a full cage.

I don't have the rules on me.
But i'm pretty sure that's how it is.

chris
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Post by chris » Wed Jul 31, 2013 2:02 pm

Yeah - I have found some door bars from Flyin' Miata (I think) that will get around this law..

They are bolt in bars, so if there is an issue, unbolt them :)
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Post by BRM » Wed Jul 31, 2013 2:05 pm

Yeah, that's the rest of it!

marcellarius
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Post by marcellarius » Wed Jul 31, 2013 3:17 pm

http://lvvta.org.nz/documents/standards ... Impact.pdf

This document defines the A-zone (area where the occupant sits), the B-zone, which is everywhere else in the cabin. It also defines the C-zone which are the areas where it's pretty unlikely anyone would impact in an accident (behind rearmost seats, below seat cushion height, forward of the steering wheel etc.)

A rollcage or rollbar is permitted in the B-zone , any bars adjacent to the A-zone must be padded.

As long as the door bars were in the B-zone or the C-zone, I don't see why they would be a problem. I went and roughly measured on my car, they should be clear of the A-zone.

As the car doesn't have a permanent roof, a roll-cage is permissible without an authority card, so a logbook wouldn't be necessary unless you wanted to get the roll-protection homologated so that you could use it for motorsport events.

Having said that, it's probably best to double-check with an LVV certifier...

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Post by SkilletKid » Wed Jul 31, 2013 8:00 pm

marcellarius wrote:http://lvvta.org.nz/documents/standards ... Impact.pdf

This document defines the A-zone (area where the occupant sits), the B-zone, which is everywhere else in the cabin. It also defines the C-zone which are the areas where it's pretty unlikely anyone would impact in an accident (behind rearmost seats, below seat cushion height, forward of the steering wheel etc.)

A rollcage or rollbar is permitted in the B-zone , any bars adjacent to the A-zone must be padded.

As long as the door bars were in the B-zone or the C-zone, I don't see why they would be a problem. I went and roughly measured on my car, they should be clear of the A-zone.

As the car doesn't have a permanent roof, a roll-cage is permissible without an authority card, so a logbook wouldn't be necessary unless you wanted to get the roll-protection homologated so that you could use it for motorsport events.

Having said that, it's probably best to double-check with an LVV certifier...
Yea I've seen that document and figured I'd ask anyway. Just so anyone who's interested in doing something similar, the A zone ends around about where the side bolsters on the stock seats start (coming from the center line of the seat). So the door bars will most likely need new seats.

Didn't know that rule about the homologation. Is homologation just for wheel to wheel events at tracks or rallies/hillclimbs as well?
"Yes, you got that, 16 years of [MX5] ownership and you too can become the Obi-wan Kenobi of not giving a s**t." - Moti

marcellarius
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Post by marcellarius » Wed Jul 31, 2013 8:54 pm

For open-top cars, roll protection is optional for Clubsport Basic (motorkhana, autocross, standing sprints, single car circuit sprint). A safety roll bar is mandatory for open vehicles in Clubsport Advanced events (bent sprint, hillclimb, multi-car and street sprints, grasstrack racing, rallycross etc.)

A safety cage is mandatory for all vehicles in other race and rally events.

For drifting, Schedule DR says that for basic level events (solo drift), a rollbar is optional (doesn't mention open top cars); a safety cage is mandatory for advanced events (team drift, drift battle).

Schedule A (Driver and vehicle safety):
http://motorsport.org.nz/sites/default/ ... ch%20A.pdf

Schedule C (Clubsport):
http://motorsport.org.nz/sites/default/ ... ch%20C.pdf

Schedule DR (Drifting):
http://motorsport.org.nz/sites/default/ ... h%20DR.pdf

SkilletKid
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Post by SkilletKid » Wed Jul 31, 2013 9:41 pm

Cheers for that marcellarius!
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NicF
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Post by NicF » Thu Aug 01, 2013 9:38 am

So door bars are ok as long as they have 10mm padding?
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Post by SkilletKid » Thu Aug 01, 2013 11:49 am

NicF wrote:So door bars are ok as long as they have 10mm padding?
The LVVTA document says a minimum of 15mm and meets SFI specification. So I assume the pool noodles are questionable and will need this stuff:

http://www.racetech.co.nz/racetech.shop ... cts_id=506

edit: found one
Last edited by SkilletKid on Thu Aug 01, 2013 11:51 am, edited 1 time in total.
"Yes, you got that, 16 years of [MX5] ownership and you too can become the Obi-wan Kenobi of not giving a s**t." - Moti

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Post by marcellarius » Thu Aug 01, 2013 11:49 am

From the LVV interior impact spec
2.4(9)
c) all sections of a roll-bar or roll-cage positioned adjacent to any A-zone must be covered in a high density energy absorbing material, which:
i) meets SFI specification 45.1 or another equivalent motor-sporting specification, and
ii) is not less than 15mm in thickness in the area facing the occupant cell
I'm not sure I'd bother with door bars without going for a full cage, the windscreen is likely to fold in a roll-over. Even then, fitting that under the top would put bits of metal fairly near my head...

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Post by NicF » Thu Aug 01, 2013 12:13 pm

Ah yes, I was looking at dashboard specs.

So what constitutes "adjacent"? All B zone is adjacent to A zone, so according to that rollbars should be padded. It seems to me that if a door bar is outside the A zone and totally withing the B zone ie more than 160mm from the seat centre, it wouldn't need padding.

I'm going for a bolt in one anyway, apparently they stiffen it up a lot.
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Post by SkilletKid » Thu Aug 01, 2013 12:14 pm

marcellarius wrote: I'm not sure I'd bother with door bars without going for a full cage, the windscreen is likely to fold in a roll-over. Even then, fitting that under the top would put bits of metal fairly near my head...
The problem with a full cage in a street driven car (apart from the difficulty in ingress and egress) is even with the padding, I'm not sure I want to hit my unhelmeted head on the top members along the roof in the event of an accident.
I agree that the windscreen will fold in but with a sufficiently tall rear hoop, then it should prevent the windscreen from folding completely flat (like this: http://bethania-garage.com/images/crash ... rdbar3.jpg and http://bethania-garage.com/images/crash ... rdbar2.gif). I know the full cage prevents this but compared to a stock MX5 without any roll protection, it does at least help with the issue.

Back on topic of the door bars, in my opinion the goal in adding them is to increase the rigidity of the chassis (if welded, not sure how well bolt in ones would do in stiffening up the body) without the hassle that a full cage on a street car adds. But take my opinion with a grain of salt, I might be complete wrong with these ideas.
"Yes, you got that, 16 years of [MX5] ownership and you too can become the Obi-wan Kenobi of not giving a s**t." - Moti

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Post by marcellarius » Thu Aug 01, 2013 12:30 pm

I have enough trouble folding my legs into my '5 as it is, especially if I'm wearing boots :D door bars with a low bucket seat seem like they'd make that even worse

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Post by SkilletKid » Thu Aug 01, 2013 12:37 pm

marcellarius wrote:I have enough trouble folding my legs into my '5 as it is, especially if I'm wearing boots :D door bars with a low bucket seat seem like they'd make that even worse
Haha it probably would in your case then. But I'm short with bones like jelly so I think I'll be fine.

Also (not quite the same since it has stock seats);

http://www.youtube.com/watch?v=pxbKy-FbSEE
"Yes, you got that, 16 years of [MX5] ownership and you too can become the Obi-wan Kenobi of not giving a s**t." - Moti

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Post by SkilletKid » Thu Aug 01, 2013 12:47 pm

NicF wrote:Ah yes, I was looking at dashboard specs.

So what constitutes "adjacent"? All B zone is adjacent to A zone, so according to that rollbars should be padded. It seems to me that if a door bar is outside the A zone and totally withing the B zone ie more than 160mm from the seat centre, it wouldn't need padding.

I'm going for a bolt in one anyway, apparently they stiffen it up a lot.
Adjacent I assume means anything parallel to the A Zone that the seat does not cover (reference Furai's issue with the cert for his car and padding for the passenger but not driver since the seat blocked the bar). So that would mean padding for the section of door bar that the seat bolster does not cover, but the main hoop section between the 2 A zones does not need it (Again if the seats do not block the sections of the main hoop behind the driver and passenger then that will also need padding).
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Post by Keith Jones » Thu Aug 01, 2013 3:53 pm

I used some stuff from Para Rubber on my car when it was both road legal and track only. It's only 12.5mm thick, and doesn't wrap fully round the bar, as you can see in the photo, but doesn't take up too much space either. I'm not sure whether the LVVTA rules specified >15mm thick when I got my certed (2004) but the MANZ scrutineers were always happy with it. Can't remember the cost, but it was much cheaper than the proper padding from Racetech or Cardwells etc. The OD is about 57mm and the ID 32mm.
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SkilletKid
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Post by SkilletKid » Thu Aug 01, 2013 4:21 pm

Yea, MANZ isn't too particular with the padding. Alot of the V8 race cars here in NZ run those "pool noodle" pads.

Maybe the LVVTA changed the padding rules recently?
"Yes, you got that, 16 years of [MX5] ownership and you too can become the Obi-wan Kenobi of not giving a s**t." - Moti

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