cro mo is not recognised by FIA, but cams still allow it, and ANDRA love it.

 

trouble with cro mo is you need to heat treat it after you weld it, which is hard when its in a car.

 

weight saving really isnt "that" great anyway...

 

or thats my understanding anyway. YMMV.

 

 

cheers, andy

still researching roll cages and found this.. thought it was pretty relevant :y:

 

Your first consideration, assuming you have a known budget, is which type of material to use to construct the ROPS. There are currently two types of material currently being used to construct ROPS in Australia. The first choice of material is a 1020 grade mild steel CDW tube which is approved for use by CAMS. The minimum strength of this material is 350MPa (Yield strength) If the Roll cage design complies with standard design principles laid out in the CAMS regulations then it only requires registration to be used in Australian competition. The second choice of tube is a 4130 Chrome/Molybdenum tube of around 650MPa yield strength . This tube is a higher tensile tube which is not approved by CAMS/FIA unless the scope of design is approved and tested by an FIA approved engineer. Because these tubes are of a higher strength, clever design will enable the ROPS to be constructed using tubes with a reduced wall thickness. This is where the weight is saved but it must be said that the ROPS design and welding processes of these tubes is more critical.

Almost correct. CDS tube is the preferred CAMS tubing, however CDW is still acceptable.

Just thought i'd post the link as to where i'm sourcing this from

 

http://www.rollcages.com.au/facts.html

Pretty sure that's old information. It used to be that CroMo cages had to be independently engineered and registered with CAMS, but now I'm near 100% sure that you can't even do that, it's CDS/W or nothing.

With CroMo cages the typical weight used to be 35kg which was for ~40metres of tube in the car but now they're using CDS/W and have upped the minimum size for the Main Hoop, front legs and increased the number of diagonals.

If you're looking at a CAMS rollcage you really need to see someone who's familiar with the requirements, or better still get yourself a copy of the CAMS Manual of Motorsport, which has a complete schedule on Rollcages, the requirements and the minimum basic design.

From there, I get hazy on things. I've only ever seen cages Homologated as part of the logbook for the entire car. The cage will need to be inspected by a CAMS scruitineer as a minimum and at least for Logbooks CAMS required photo's of the car. If it's just going to be a CAMS compliant cage inside a khanacross bunky or whatever, you'd do best to chat to an experienced cage builder or a CAMS scruitineer for the exact process behind that.

Just be careful, at the moment the regs are being discussed and I think there's some fairly big changes coming along (been some discussion on the rally forums) and it's going to catch some people out.

2012 regs are already out and accessible on the cams website, and i thought you still could run cro-mo, but i don't know why you would.

cages can only be logbooked with the whole car from my understanding, and still gets scrutineered at events log book or not.

 

 

cheers, andy

So Andy, its been 6 months lol

yep,. and nothings happened.

 

cheers for reminding me :down:

Haha all good I haven't even thought about a cage since