Sydney roll cage fabrication

[mitch_f1]

I have been surfing the internet of late (dangerous I know), and I've been watching a few videos of roll overs, and have been getting quite paranoid about roll over protection. Sure the roll bar is okay, but if you follow the angle between the top of the bar and the bonnet, it doesn't leave much head room. As a result i am looking into possibly getting a full roll cage made up, as more than 3/4 of the driving this car does is either on the track or to/from the track, and I intend to get into a lot more motorsport very soon. So I have just a couple of questions please

-Who makes roll bars for MX5s. I would ideally like a known quantity; someone who has made one before, and who someone has been happy with
-You see roll abrs around the place that are bolted up (I.e. carbing, mazda speed). How are these for safety? I would have imagined that they would fold up in an accident? If I just had my torque box bar, and had a front section and roof bars added to it, how safe would that be?
-Welded vs bolt-in. If I were to get a full cage obviously welded would be the safest, but then that brings its own set of troubles, the primary of which being that it is permanent. How does a welded in cage compare to a bolted in cage (if the structure were otherwise identical).

Thanks guys/gals

[Guran]

These guys come highly recommended for custom-made cages. No idea if they've worked on MX-5s though.

http://www.pcdengineering.com.au/

They made a cage for a friend's MINI JCW that is used for rallys.

http://forums.mini-mods.com.au/showthre ... ject/page9

I'd suggest you study the CAMS Manual before speaking with a cage builder, and make sure you have a reasonable idea of what sorts of features you're after.

http://www.camsmanual.com.au/pdf/10_gen ... J_Q111.pdf

Oh and keep in mind that the cage must be 50mm higher than the top of your helmet while seated.

[Old Dude]

You might also have to check the legality of driving it on the road with a full roll cage.
Cheers
Dale

[mitch_f1]

I'm fairly certain that with an engineers certificate and plate it will be fine.

[de Bounce]

You might want to have a read about the National Code of Practice for Light Vehicle Construction and Modification (NCOP)

Not all states are signatories yet so you will need to check with your state.

The one you are interested in is NCOP7 Seating and Occupant Protection
The following is an extract from page 41

1 SAFETY
The majority of internal roll-bars or roll-cages were originally designed for use in competition vehicles where the driver and any passengers are required to wear helmets. In normal road use, occupants of motor vehicles do not wear helmets, therefore any modifications to the inside of the cabin must be carefully designed to reduce the risk of injuries to all occupants in the event of a crash.

Six-point roll-cages that have supports running down the A pillars and B pillars, and braces running to the rear are not acceptable for normal road use as the additional forward supports are likely to constitute an increased injury risk to front seat occupants in a crash. They typically decrease visibility for the driver and usually prevent the correct positioning of sun-visors.

Registration Authorities may allow the use of specialised or six-point roll-cages for competition purposes. However, in these cases, the vehicles to which they are fitted have restricted access to the road system or are conditionally registered. Persons who wish to fit specialised or six-point roll-cages for competition or other purposes must consult with their respective Registration Authority for further information.

Good luck

[bigdog]

Daniel Deckers has built cages for a number of MX5 racers in NSW - PM little decks on here (Daniel's son) to contact him.

[mr2 spyder]

I've a Syd local that builds cages for Speedway action looking into a full street legal cage.
If you like, I can give you an introduction to him to discuss your desires further.
May help me when I've the $$$ to get the cage done.

Irrelevant where you get it done, if they don't insist upon mounting the seats to the cage, turn around and run, as they've obviously NFI !

Sorry I have NFI. how do you mount seats to cage?

[mitch_f1]

Seems likea very valid point, but I have not seen many cars with this done, not even full on race cars. Neither have I seen many cars whose floorpans have disintegrated?

I can't find it now, but there was a car that rolled over at a club day in the US a few years back, either a mustang or a BMW, can't remember. But the feet of its cage went through the floorpan!!!

[greenMachine]

I've a Syd local that builds cages for Speedway action looking into a full street legal cage.
If you like, I can give you an introduction to him to discuss your desires further.
May help me when I've the $$$ to get the cage done.

Irrelevant where you get it done, if they don't insist upon mounting the seats to the cage, turn around and run, as they've obviously NFI !

Sorry I have NFI. how do you mount seats to cage?

The cage is your life preserver.
You want to stay within that, not the disintegrating body around it.
Also, you've probably harnesses mounted to the cage, they're useless if the body and cage separate, aren't they ;)

I apologise if I come across as condescending upon this one, yet until recently I didn't even know this and am surprised by how many places that thrust a professional image forward fail this simple concept and couldn't live with myself if I didn't share safety information with the members here...

Any roll protection needs to incorporate seat mounts as a part of it, otherwise it might as well be a WRX bling special.

Think about it and I'm sure you will realise why you WANT your seat mounted to your rollcage...

I suggest you think about it some more.

I am not saying that, in all cases, a seat should not be mounted to the cage. I am saying that it is not necessary in all cases. Not being an engineer who studies the design of these, I suspect it is a case of horses for courses. A modern car's structure has been designed to safeguard the occupants through seating and belt mounts that can handle a big impact. You would not say the same about say an Elan, and if I was building a cage for an Elan I would be looking closely at the seat AND the harness mounts.

Having said that, it needs to be remembered that the basic principle is energy absorbion, which means that the structure does move in an accident. That obviously has implications for seat and harness mounts.

I would be careful about generalisations on this complex issue. I would defer to people who have looked at it with more careful and better eyes than mine. In this context I am not aware of any requirements along these lines from CAMS, for what that is worth.

If anyone is building a cage, and is concerned about seat and harness mounts, I suggest they get better advice than can be found on the interwebs ...

[hks_kansei]

I thought mounting seats to a rollcage was not allowed by CAMS rules?

same as how mounting a harness to the seat isn't allowed.

[rob323]

I can only ever see that principle being possible with cars with space frame type chassis's. Certainly never seen it applied to production cars.

[hks_kansei]

true, Sprintcars were mentioned, which yeah, they're basically a tube frame chassis with thin alloy plates to just cover up gaps.
so yes, in those cases yuo can't mount to the floor, becasue the floor is just a thin sheet.

in a car though it's much thicker and strengthened around the seat base area where that little hump is.

pretty much the same as this Ford Fiesta Rally car.

[deviant]

Seems likea very valid point, but I have not seen many cars with this done, not even full on race cars. Neither have I seen many cars whose floorpans have disintegrated?

I can't find it now, but there was a car that rolled over at a club day in the US a few years back, either a mustang or a BMW, can't remember. But the feet of its cage went through the floorpan!!!

Like this one: http://jalopnik.com/#!5390934/mustang-...over-tire-wall

Bolt in cages

[mitch_f1]

Thankyou, yes. That is exactly what I was looking for!