curren roll cage design.

[Infinite]

Ok, im geting back onto my main project now as i cant paint it untill the cage is done!. so here is one for all your cage builders


just made a picture from the msnz spec shet, basicly im not 100% sure on what steel i use on what section of the cage and what braces i should go for so want to just double check!



Is it an over kill? with the angle bar at the back from left corner to right and then the flat bar from left to right? also with the cross bar in the roof? i have to take the 2 arms thru the firewall as i want to remove the air bag system from the vehicle. what about the side impact bars, after reading it my understanding is that these are only needed if u modify the door's/door covers? but personaly i will put them in anyways just for safety. ok so onto the sizes my understanding is the parts i have colour in black are "other members" and are constructed out of 40x2.0mm or 38x2.5mm or 38.1x2.5mm and the white/clear sections are "main rollbar" and are to be constructed out of 45x2.5mm or 50x2.0mm or 38.1x2.5mm correct? what sizes would be best to go for. any help would be greatly apreshiated!

Also were it mounts to each point of the body there must be a patch of 120cm and atleast 3mm thick? and this patch must be fully welded? and the 2 rear arms must be on a 30 degree angel??

thanks!

[85AW20v]

PM Leon. He's the man who approves these once you've built them and put them in for homologation. The 38.1 x 2.5 is the usual size people use and construct the whole cage out of it - you don't have to think about what sizes go where then. You might also think about a horizontal bar either halfway up the backstays or between the main hoop behind your seats to attach your harnesses to.

Depending on what you are going to use the car for can have some influence on what you put into it. For rally work, as strong as possible - it's a long way down off some roads if you get it wrong. For circuit work only, you might not need the cross brace in the roof but then again it all helps to stiffen the car which makes suspension tuning easier if the car isn't flexing.

Have fun!!

[Infinite]

thanks for that, mainly want it for track but also will do the odd sealed rally yea i did think about the seat belt one but forgot to put it in!

[fangsport]

ideally, you also want a bar that goes from side to side at both the A and B pillar. while its good to fit the intrusion bars across the doors, you have nothing stopping the whole side of the cage pushing in ( poles and trees are not very forgiving).

[Cahuna]

Likewise, bars running from the B-pillar (main hoop) to the bottom of the C-pillar (rear laterals), especially if you are going to run the shoulder straps for your seatbelts to the rear bar. I've seen a car that landed on it's arse after dropping 10-20m down a bank and without those bars the rear section crushed forward, loosening the belts.

[RedMist]

ideally, you also want a bar that goes from side to side at both the A and B pillar. while its good to fit the intrusion bars across the doors, you have nothing stopping the whole side of the cage pushing in ( poles and trees are not very forgiving).

The Currens / Celicas have a massive "bridge" on the leading edge of the back seat. You shouldnt have any issues with the cage pushing in so long as you tie the main hoop in well.
My cage is reasonably similar (although considerably more bracing in the door area). I dont know if you will need the roof bars, the distance between the main roll hoop and windscreen top brace is very small. You'll also find that you'll have to sit very close to the celiing in order to see anything. Cross bars in something as curved as the Currens roof will limit the amount of room you have in the car. Still you should get a better idea once the cage has started construction. Another thing you may consider is corner bracing the main roll hoop against the front bars. It adds more weld area so that you cant snap off the front bars and should help prevent skew if you put it down on its windscreen. Also the bars mentioned by Cahuna are a must. Any rear punt will direct load up to the peak of the cage only. You could run them as Cahuna has suggested or run them through to your top door cross member. However if you did that I'd also run a lateral across the car in the main roll hoop between the two mounts. This should stop a rear punt pushing the cage outwards. I chose to run mine as Cahuna suggested as I think it will distribute the load through the car more evenly.

If I can stress one thing.... these cars may appear big inside.... but they are stupidly tight! MOUNT YOUR SEATS FIRST! Then appropriately place the main roll hoop. I think you'll find it considerably further back than expected. In my Celica we constructed cage before mounting seats and then found that I sit directly under the main hoop. I am 6'1" and do like an Italian driving style and it makes the Celica feel like a mini. You'll also have to mount the seats very close to the centre of the car. I had to "manipulate" the tunnel and then reverse the two inside seat mounts (the L of the bracket sits under the seat) in order to get me and my co dog in the car.

An old photo of the cage. We removed the main roll hoop cross brace as we would have had to put a large hole in my head to accomodate it.

[RedMist]

ideally, you also want a bar that goes from side to side at both the A and B pillar. while its good to fit the intrusion bars across the doors, you have nothing stopping the whole side of the cage pushing in ( poles and trees are not very forgiving).

The A pillar already has a large (approx 40mm) mild steel bar that hangs most of the dash equipment and also mounts to the floor. Its overengineered for its intended purpose and should serve to strengthen the cage somewhat. You'll need to tie into it when you run the cage down the A pillars anyway. It's not as stong as I would like (as its bent) but replacing it and then attempting to construct new mounts for or modify all my dash equipment was too much of a hastle for a lazy bastard such as myself.
B pillar, The amount of steel in the rear seat "bridge" is huge. If you tie it in well I cant see any issue with sideways collapse of the car. There is also another brace under the front seats thats double skinned. Its understandable why the Celica's / Currens are so heavy.

At the end of the day adding steel in the right places will add to the safety aspect of the cage. Its just a matter of thinking through where the loads will be positioned in a roll / impact and attempting to shield the occupants from any distorsion caused by those loads. I chose to add about 14 more bars than required by MSNZ for several reasons. 1. I'm an agressive driver. 2. I like things fast... and safe (I'm old) 3. One of my co-dogs has 3 children. 4 I'm an agressive driver.
I could have continued to add steel, but from my viewpoint all possible loads were catered for and the MSNZ regs were far exceeded.

[Infinite]

thank you for the great reply and i will be changing some of my cage, i am about 5,5 and sit fairly well forward in the curren i like to be up close and personal with the vehicle hah, I also still will be driving this car to and from events and also will possibly use it when my other cars are being worked on as i cant ever seem to keep a daily driver lol so i dont want to make it to hard to get in and out of the vehicle, but the extra bars by the a pillar look like a realy good idea and would add alot of extra support to the front hoop. With the bar for the seat belts that goes to the main hoop behind the driers seat or further back? my father used to rally long time agao and unfortinitly has had a stroke so cant help me much but he had a mate who rolled a vehicle and the vehicle bent in half and the belts killed him as they pulled tight when the car bent? but if the bar is fitted to the hoop behind the seats this sould be fine?, I have also been in a major crash i was luckily to get out of alive so want a good strong cage because once is very lucky and i dont think id be so lucky if it happend next time.


Would u have a picture of how u tied the front dash support in? and how u also put it onto the front strut towers? would be greatly apresheated

[Leon]

MANZ = Motels New Zealand.

MSNZ = MotorSport NZ.



Best mounting point for a harness is 6" (15cm) behind seat, exactly flat with persons shoulders.

Unless you are tall, put your diagonal in the main hoop, not in the backstays. That creates a nice strong section above your noggin. If you have the only diagonals in the back stays, you create a nice strong point above the back window. Which one is more important to you, noggin, or back window?

Transverse in the main hoop running from side to side, and picking up the transmission tunnel is also a very good member to have, as others have said too.

Lateral support bars (45 degree or so) angle from the main hoop, running up to the lateral bars are good in a structure without an A pillar support ( = bar running straight from lateral bar top bend to lateral bar front footing as seen in redmists door opening photo.

Cages are a MASSIVELY debatable area, as people have their own pet bars, and particular likes and dislikes. The structure you have drawn will be as strong as hell, and make a lot of big crashes very survivable if you've also got a good seat. My suggestions are based around the basic principle that "triangles are your friend", and that "the most important part of the car is the driver".

If I remember, and this thread is alive, I'll try to make the time on Monday to knock out a couple of drawings of cages that have a lot of stuff I've seen, that I have liked. Since I've homologated about 3000 cages in the last five years, I've seen some really cool stuff, and some really shit stuff.

You're asking in the right forum though, as there are some bloody clever people here.

[Infinite]

thanks i have decided to go with a steal frame seat, as i had them in my mazda familia when it rolled and ive seen the damage i did to it! my body impact moved it about 100/150mm out of shape! and i think that kind of abuse would rip a fibreglass/carbon/kevlar seat and have seen the lower strap that goes gound your family guells rip thru and go back about 100mm! in a kevlar seat!

[Leon]

Steel seats have pro's and cons. Ask GoldAE86 about his steel seat, as he ended up with broken ribs from a Momo T-frame after a roll.

I'd personally (this is just my own personal opinion) only use an FIA approved seat. By preference, Racetech. Again, this isn't my opinion as a motorsport worky type person, purely my personal opinion as a petrolhead. I think you can get an awfully good racetech fia seat for some stupid price like $550 + gst (as best I recall).

If you're removing airbags and wanting to keep the car legal, you're going to need an FIA seat anywho.

Seat tearing tells me the harness angles were on the piss. The webbing in theory shouldn't pull anywhere "on" the seat, but should pull through the hole in a "straight line" for lack of better words.

[Mr Revhead]

the crotch strap isnt made to hold the seat... sounds like that one broke off its mounts.

recent article i read mentioned that several incidents lately involving top notch seats breaking off mounts appeared to be the result of incorrect fitting. like using washers to space the brackets to the seats.

leon, you know more about that?

[Leon]

I wouldn't say "top notch" seats... more "well known brand name". Well known in the rally fraternity for breaking too.

Poor seat mounting was half the problem. Plenty of support area with the seat is a good thing. Tiny little support brackets on the seat were half the reason for a recent catastrophic seat failure. The other half of the equation was that the reinforcement for the fitting moulded into the seat was WAY smaller than it should have been. WAY WAY WAY too small.

[Infinite]

Ok, i will admit the seat definitly gave me some hurting spots thats for sure!. ok so i have just changed the cage drawing to incorporate the strp bar hopefully the hoop will be in the right place for spacing the belts at the right distance. also added the bar to brace the rear roll bar from ds side to ps side. also have added the brace to the floor tunnel and the brace down the a pillar.



The only part im not 100% sure about now are the angels with ill start reading again. and also the tieing into the front dash support.

[Mr Revhead]

i would post some of the article up, but resident woman thing has done cleaning and i cant find it

[RedMist]

Ok, i will admit the seat definitly gave me some hurting spots thats for sure!. ok so i have just changed the cage drawing to incorporate the strp bar hopefully the hoop will be in the right place for spacing the belts at the right distance. also added the bar to brace the rear roll bar from ds side to ps side. also have added the brace to the floor tunnel and the brace down the a pillar.



The only part im not 100% sure about now are the angels with ill start reading again. and also the tieing into the front dash support.

Gets to be a tonne of bars in a very short time doesnt it!

You still havent got anything from the lower main roll hoop to the rear struts.
You also have the top windscreen supports running from the roof which I think will make the door opening too small for you to get into. Mine runs about 100mm down from the windscreen crossmember. I also wouldnt copy my design for those bars. Brent Tiny built mine with an attempt to minimise dash cutting. If I were to do it again I'd probably mount it on the inside of the door cross and mount it directly to the front foot. To hell with the dash.
I've also seen that central foot with a lateral bar to the horizontal through the main hoop before... and I still have no idea as to why its there. I can't see any load that it would stop.

[strx7]

you'll soon have 20+ metres of tube into your car and think, sh1t, where did that all go to. As Leon said, occupant safety is the number 1 thing to think about when building cages. Being short you dont have the big can of worms that us tall guys have to worry about - I'm 1.93m makes seat mounting positions lots of fun I tell ya.

[Infinite]

The front hoop design wont be identical to that as i want it runing very tight to the front window and also dont want to cut the dash up heaps. ok ill add the bottem braces at the rear to also remember the curren has a boot not hatch so alot stronger again.

[RedMist]

True, boot may be stronger but without those braces a shunt in the rear will try to push the cage upwards.

You'll have to forgive the fact that its only half been sprayed... but you get the idea.... God the flash makes it look like shyte.
You can see how close the windscreen top brace is to the main roll hoop. I think it will get very "busy" with a crossbrace through it.

Leon my "Roll Protection Homologation application " form is on its way to you, pictures without paint.

[RedMist]

The front hoop design wont be identical to that as i want it runing very tight to the front window and also dont want to cut the dash up heaps. ok ill add the bottem braces at the rear to also remember the curren has a boot not hatch so alot stronger again.

I doubt if you'll get it any tighter than Brent Tiny has with my cage. Its very well constructed, very tight to all panels. If you want to cut the dash as little as possible then the design I have is about as good as its going to get. But I wouldnt recommend compromising safety in aid of not cutting your dash.
If you do copy that portion of my design, you might want to direct the bar between the door crosses more towards the front foot.
I rather like the windscreen top brace on the PBMS cars. Its a sort of a Y design that should distribute load better than the traditional 90 degree brace thats in the likes of my cage.