Not this again - Tube/Pipe sizes for competition cages

[Damo]

I've been doing a bit of searching and reading on this topic, and there is quite a bit on this board been said already. From what i've found there is basically two 'standards' out there:

1. 1.5" x .120 (38mm OD x 3mm wall). As can be used in WeRock and OzRock. The popular 32NB meets this standard.

2. 1.75" x .090 (44.45mm OD x 2.5mm wall). As specified by CCDA, Qld Transport and the draft version National Code of Practice for Light Vehicle Construction and Modification. 32NB doesn't meet this standard (strictly speaking) as it's only 42.2mm OD. AND i'm not sure if you can get pipe in the required CDS or CDW material.

One way to get around this is may be to just go with 40NB, which is pretty big (48.3mm OD). So there is a weight penalty, and more steel = more cost. BUT according to CCDA they want CDS or CDW, and i'm not sure if that's available in pipe.

So for the guy that wants to build a cage, and keep his options open what does he do???

NOTE: I have been pretty careful in making sure that what i've written here is correct. If you know that something is wrong PLEASE let me know and I will change it. I am hoping that we can compile some information and have a definitive source of info that allows people to make an informed choice.

Pre-emptive strike on some questions...
NB = nominal bore
OD = outside diameter
CDS = cold drawn seamless
CDW = cold drawn welded

[Tiny]

Pre-emptive strike on some questions...
NB = nominal bore
OD = outside diameter
CDS = cold drawn seamless
CDW = cold drawn welded

bwaaaahahaha

voted 44.5

[jav]

hydralic pipe is seamless, therefore stronger i think, it's avaliable in heaps of different sizes.

[awill4x4]

hydralic pipe is seamless, therefore stronger i think, it's avaliable in heaps of different sizes.

Yeah, and this is where a lot of people get caught out because hydraulic tube is usually annealed as well so it's as soft as buggery. We've had chassis' in at work to straighten and when we used the porta power to push them back they were like plasticine with no real strength to speak of.
If you go "cold drawn" (cdw) then go for tubing like "Racetec 350" (which is just a brand name) If your in Sydney there's about 3 suppliers there who can supply "chassis grade" CDW. British International, Performance Metals and Rod Andrews. My pick here is Performance Metals, we deal with Mathew Maude there and he's a good guy to deal with.
Regards Andrew.

[bru21]

there seems to be a perpetual cloud of worry over this topic wher there needent be. build it right to meet the codes and it will be plenty strong enough. i would use off the shelf steel as 1 they can't tell and 2 its mpa is not far off and how many times have you seen pipe split etc and 99% of the time it will be migged with whatever is in the gun that resembles steel (just look jow mig welding rusts and see the impure steel) i used off the shelf 38od with a seam for the whole internal (b pillar 48.3 x 3mm) which is just for show (qld comps don't recognise exo's) as i have an exo made of 48.3x3mm 8 point. the internal in mine weighs next to nothing. the big mistake people make with cages as they use small diameter in thick walls. 48.3 x 1.6 (50.8 x 1.6 is the available size) is prob heaps stronger than 38 x 5mm except where crushing against rocks etc is concerned. the second mustake i see a lot of people do is get obsessed with the weight. a cage has what comes down to say 2 lenghts of tube. in 48.3 the difference in thickness vs weight is about 6 kg a length from memory from 2.4 to 3.2 as the thickness moves to the inside and fill a reduced diameter thus doubling the thickness does not double the weight.

lastly i have seen so many with 8-10mm base plates. that is far weaker then a thinner one as the flex cracking is a big problem. legally you can only weld metal 1.5 x the thickness to a chassis or body etc.

[ljxtreem]

DOM 1.75 inch, 1.5 inch

Mock

[GQ Bear]

Getting off track a wee bit, does anyone know if there are min/max specs in relation to how close to pillars, roof, occupants heads,etc when it comes to cages? if so what are they? and is rubber cushioning required or optional?

thanks

NOTE: I have been pretty careful in making sure that what i've written here is correct. If you know that something is wrong PLEASE let me know and I will change it. I am hoping that we can compile some information and have a definitive source of info that allows people to make an informed choice.

can't wait to read it Damo, let us know when your finished

[Tiny]

go to the CCDA site for the specs on CCDA sanctioned events or get hold of a CAM book, depends on what class though

[davejb]

Vicroads web site has the specs on cages for rego requirements in Victoria
Dave

[GQ Bear]

ta