Roll-over protection

WideOpenThrottle · Post by **WideOpenThrottle** » Wed Sep 14, 2011 11:57 am

Just starting to think about what i need to do in this department.I will only be needing behind the seats to satisfy Playday requirements so i would need to know.....

Can i use aluminium or is steel the best?

What pipe dia if either is used should i go for? [i believe 45mm is preferable}

Do you have to weld or can it be just bolted to the car?

Thanks to anyone in advance

RMS · Post by **RMS** » Wed Sep 14, 2011 1:22 pm

Ask these guys:

http://www.lvvta.co.nz/

Afaik unless you are using it for motorsport and as long as it doesn't come forward of the seats you can do what you want? I'm no expert though.

WideOpenThrottle · Post by **WideOpenThrottle** » Wed Sep 14, 2011 3:41 pm

Thanks RMS -you are right about rear of the seat thing-i am more after doing it according to motor sport safety build requirements just to ensure i get something thats up to strength if the unthinkable should occur!

Angreal · Post by **Angreal** » Wed Sep 14, 2011 3:50 pm

Something like this? http://www.youtube.com/watch?v=vGHzyNJ3-kI

SLYDIT · Post by **SLYDIT** » Wed Sep 14, 2011 4:28 pm

if its just for clubsport stuff then anything goes really. if you want to do gravel or circuit racing with other cars you'll need a MSNZ spec bar.

if you do a bit of googling for "brown davis" or "hard dog" roll bars then you'll see what sort of bolt in bars will be ok for a bit of weekend fun.

SLYDIT · Post by **SLYDIT** » Wed Sep 14, 2011 4:47 pm

heres a couple of pics of the brown davis

http://imageshack.us/photo/my-images/23 ... 96vuv.jpg/

http://imageshack.us/photo/my-images/23 ... 96vuv.jpg/

and a hard dog bar install...
http://www.blueridgemiataclub.org/techn ... /index.htm

that should give you a few fabrication ideas

punkoutnz · Post by **punkoutnz** » Wed Sep 14, 2011 5:36 pm

Those browns davis bars are about a grand shipped to NZ though!

RMS · Post by **RMS** » Wed Sep 14, 2011 5:49 pm

If you're in the auckland area it might be worth talking to Ray at Chubb Racing.

He helped me out installing my seat and also goes all sorts of roll cage fabrication.

He quoted me around $600 for a half cage from memory but I ended up getting a bolt in mazdaspeed cage off trademe. (could be wrong on the quote, it was a long time ago)

http://www.rollcage.co.nz/MX5_Half_Cage.php

SLYDIT · Post by **SLYDIT** » Wed Sep 14, 2011 7:42 pm

maybe this might be what your after at a much more reasonable cost....

http://www.mx5forum.co.nz/ads_item.php?id=305

punkoutnz · Post by **punkoutnz** » Wed Sep 14, 2011 7:52 pm

I'm actually saving my money for that! Focus at the moment is to get the car driveable again, then if that bar is still around it'll be buying that to get on the car. I would like a bar before I do any serious driving this summer, just for a bit of peace of mind. I'm basically after the same sort of thing you are.

WideOpenThrottle · Post by **WideOpenThrottle** » Wed Sep 14, 2011 8:40 pm

The Brown Davis is fine but i would like it to be used with my Hardtop as well as fixing points for a harness.

I have two neighbours who do welding.one could do me an aluminium one if it would be strong enough otherwise the other neighbour could do it in steel.

The million dollar question is- is aluminium suitable for roll-over protection.......???

SLYDIT · Post by **SLYDIT** » Wed Sep 14, 2011 9:45 pm

no.

you need to use 38mm or 44mm roll bar tube and a minimum of 3mm thick mounting plates

RMS · Post by **RMS** » Wed Sep 14, 2011 10:07 pm

Check this out

http://www.motorsport.org.nz/safety-structures/

WideOpenThrottle · Post by **WideOpenThrottle** » Thu Sep 15, 2011 8:18 am

SLYDIT wrote:no.

you need to use 38mm or 44mm roll bar tube and a minimum of 3mm thick mounting plates

Cheers SLYDIT- steel it is then & from what i have read D.O.M.[Drawn over Mandrel] is best[apart from moly steel which needs to be stress released if welded].

WideOpenThrottle · Post by **WideOpenThrottle** » Thu Sep 15, 2011 8:20 am

RMS wrote:Check this out

http://www.motorsport.org.nz/safety-structures/

Couldn't find any steel sizes anywhere in there??

RMS · Post by **RMS** » Thu Sep 15, 2011 9:45 am

Have a look at Schedule A

http://www.motorsport.org.nz/assets/Mot ... A-2010.pdf

There is some info towards the end of the document (Page 46) re the tube that is allowed by MANZ.

Further on in the document there is also a set of recommended designs/requirements.

Even if you're not looking to get it homologated it's probably still a good read.

There is a spec for roll cage tube that I guess steel and tube should be able to supply.

http://www.nztubemills.co.nz/pdfs/NZTM- ... cation.pdf

Growler · Post by **Growler** » Thu Sep 15, 2011 11:30 am

WideOpenThrottle wrote:The million dollar question is- is aluminium suitable for roll-over protection.......???

Yes aluminium is OK for roll over protection but MANZ don't allow it any more (Since the mid 80's from memory). I believe they still allow it in Japan though (The Gold NA MX5 that came over from Japan to do the Top Speed trials had an aluminium cage. This had to be changed over here before MANZ would let it run).
Good roll over protection is more on how the roll cage has been designed.
You could use a good quality steel but if the design isn't right and the welds/joints etc aren't of a high standard you are wasting your time.

Top Speed Trial
http://www.mx5nutz.com/forum/index.php?showtopic=51712

WideOpenThrottle · Post by **WideOpenThrottle** » Thu Sep 15, 2011 8:22 pm

Hi RMS-got the read & thanks very much-now i am getting somewhere & to Growler, yep maybe a trusted welder or ready made one might be best-i need to do more research before commiting,i may check out if Don from Autoway in Hamilton is still doing one that satisfies Playday & my needs!
Allof you who had input -its been much appreciated

Gravelben · Post by **Gravelben** » Fri Sep 16, 2011 11:23 pm

I looked at some photos of the Donbar design but didn't really like it - while it might provide some roll protection it isn't really braced backwards and won't do much for chassis rigidity like a good 4-point (or more) bar will.

Both my MX5s I owned for a while without bars before installing them and the difference in feel is really quite significant, standard ones feel a bit floppy afterwards.

Brainflex · Post by **Brainflex** » Sat Sep 17, 2011 9:24 am

Don is still doing the playday rollbars, I asked him about them last month. $350 + gst if I remember correctly.

WideOpenThrottle · Post by **WideOpenThrottle** » Sat Sep 17, 2011 9:38 am

At this stage i havent been in contact with Don to see what he does-rang on Fri but went to answerph [must have been morning tea break time]

Mr. Shine · Post by **Mr. Shine** » Sat Sep 17, 2011 10:44 am

This is something I'm interested in also, and would like something a bit more solid than the Autoway bar. Are weld-in jobs subject to the same (non-)certification requirements as a bolt-in job?

WideOpenThrottle · Post by **WideOpenThrottle** » Sat Sep 17, 2011 1:51 pm

Mr. Shine wrote:This is something I'm interested in also, and would like something a bit more solid than the Autoway bar. Are weld-in jobs subject to the same (non-)certification requirements as a bolt-in job?

From what i have read it seems to get a cert the whole fabrication & installation needs to be signed off by a recognised person[s] whether bolt -in or welded following the motor sport guidelines as per their schedule.

For me i shall be following the guidelines just for my own personel safety & should the need arise then hopefully a cert is possible?

Gravelben · Post by **Gravelben** » Sat Sep 17, 2011 2:37 pm

For motorsport it obviously needs to be certed/homologated/whatever for anything beyond basic clubsport.

For road (or track-day) use no cert is required provided the bar is behind the rearmost seats - at least thats definitely the case with bolt-in, not sure if weld-in is any different.

punkoutnz · Post by **punkoutnz** » Sat Sep 17, 2011 4:21 pm

So you're saying Don's bar is just the single hoop? I really want at least a 4 point bar for my MX5. With so many people here interested it might be an idea to get together a group buy situation for anyone prepared to make these roll bars, could save us all a few quid.

Roll-over protection

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