Roll Cage Choice - Steel/chrome Moly

[tk80]

Hey guys

Starting to get a bit more serious about tracking my 33 gtr. Wanted to get opinions on the best way to go...whether to buy a steel weld in or spend the extra $'s and get a weld in chrome moly cage? What is the price difference between a steel 6 point vs chome moly? How do the cusco chrome moly ones compare to aussie ones? can you buy a cusco one and then weld it in? Can you go around the dash and still have sufficient roll over protection?

On another note, i know there is a lot of threads about this stuff.....but who on here can recommend anyone in sydney?

thanks in advance.

Edited January 2, 2009 by tk80

[Risking]

My opinions on the questions you asked.

Chromoly will always be $18-24 per meter more expensive for the raw material.

It is slightly more expensive to bend due to the expensive benders and die sets required to do a nice job of it.

It can be more expensive to weld properly as most good welders will purge it so your paying alot more for gas if its TIG'ed.

You probably wont notice the difference in materials once its done unless the car is stripped etc the weight will be negligable. Typically a length of CDS (cold drawn seamless) steel is half a kilo heavier than chromoly.

Price difference could be up too $2000 plus for a chromoly depending on the complexity of your cage.

I would not recommend buying a cusco/saftey21 etc etc. The better option is to call bonds roll bars in Sydney and buy one of their bolt in kits. Once you have the bolt in kit you can then either bolt it together yourself or send it and the car to a fabricator and have them extend the bolt in kit to suit your requirements.

The bolt in kits are cheap from bonds so it can work out much cheaper as you are not paying for bending etc or the time consuming part of designing the main hoop.

From the basic kit you can add bars where you want fit intrusions and generally build the cage around what they supply.

It saves many hours and dollars doing it this way.

The only down fall is that the hoop may not be as tighter fit as what it could have been if it was specifically made.

You can weld in the bonds kits and they also come with all the bolt in hardware as well.

If your putting front legs in dont even bother going around the dash, either do it properly or leave it as a rear half cage, those bent front legs will colapse in a decent rollover and potentially make it harder for you to get out as the fold up into the door jam area.

Before you find someone to build the cage you need to determine a budget that your happy with spending as that will be the thing that decides what type of cage you end up with.

Edited January 2, 2009 by Risking

[Roy]

Also a Chrome Moly cage doesnt fit the requirements of FIA/CAMS cages for wall thicknesses. The whole point is to use thinner gauge chrome moly as it has equal strength and less weight. So doing so require the cage to be engineered by the manufacturer that includes modelling etc to ensure that it meets the load tests stipulated for ROPS.

This cost alone often bumps the cost of a chrome moly cage in a CAMS log booked car up to close double. As Risking pointed out the need to Tig = more dollars (generally dont need to post weld heat treat bt some still prefer to do so). More difficulty in bending/workability = more money. Material= more dollars. The precision of the fit up = more dollars (tig isnt so forgiving on the quality of the fit up). And finally the engineering / certifications = more money...so all up chrome moly cages can often cost far more and unles it is a very complex cage with lots of metal then only then does the weight savign add up to tens of kgs and in my eyes is perhaps worth it.

[tk80]

thanks for you responses.

after reading this i'm thinking a weld in steel is the way to go. i don't like the idea of the bond pre-made cage. who in sydney does a good cage that isn't pre-made....as i want it to fit nice and snug.

[Risking]

you'd be better off getting intouch with someone who has a bonds cage and having a look because they are actually pretty good.

I have one here which your more than welcome to have a look at.

For what you want to do with the car id also agree with you and say CDS weld in is for you.

Is the car used on the road oftern??

Your next decisions are do you fit a full set of intrusion bars, dash bar or retain the original, how structural do you want the rear half to be.

Make a few sketches of ideas you think may be practical to your needs and take them to a cage builder.

If you give the car to someone and have them build you a cage of their own design it may not be suitable for your intentions.

There are many places in Sydney who can build good quality cages. Bonds do very good work but it does come at a cost, Sureflo exhaust in ingelburn may still do them.

Also in the same building as Textralia in ingelburn there is a very very good fabricator who does nice work as well. He helped with the design of my latest cage and is very knowledgable.

[benm]

Their are a couple of places in the Peachtree area of Penrith, 1 is Eddie at Penrith City Exhausts (whom also says the Bonds kits arent the tightest fit) and the other im not sure of the name but its whom CRD send all their cars to.

[tk80]

anyone know the crd one in penrith?

[unique1]

Just a question to Risking about mentioning the weight differences. When u say a length of cds compared to chrome moly and its 0.5kg heavier, how long is a length?

im also doing a r32 gtr and need a 6 point cage for ANDRA regulations, i was wondering how much extra weight would the same design cage add if it was done in steel compared to chrome moly? i added up something like 25m metres of tubing or so as a rough estimate, im joining into engine bay strut towers and cross in the roof and cross bar for harnesses etc on top of the usual 6 point setup needed. This is a fully stripped as light as possible track car so weight is important but if its only a 20kg difference or so overall then i'd just stick with steel, where as if its like 50kg+ then i might think abit more about which way to go.

also what is the going rate per metre for chrome moly compared to cds? (material cost only not labour)

sorry if its slightly offtopic to the original posters questions.

Edited January 2, 2009 by unique1

[Risking]

I buy my steel through racetech here in Sydney.

Their lengths can varry depending on how they were cut at the mills. However generally they are around the 6.2meter mark.

So you'd see roughly a 4 kg (over 25meters) gain in using the chromoly. Some people will argue its more but thats what I have weighed from the supplier I use. My current cage is all chromoly simply because I did all the fabrication my self so the extra labour costs were not an issue, I bent it myself so again time was no issue and welding is no problem either. The cage I did I was quoted roughly $9-12,000 by a few places (without the engineering for cams) just going off the the sketches that I showed them and the materials I wanted to be used. The same cage out of CDS mild steel was going to be roughly $6500.

Im honestly not sure what the current rate is for steel as last time I bought was in bulk before the dollar crashed.

However from memory the CDS was $28 a meter and the chromoly was $39 retail. Dont quote me on those numbers as its mearly off the top of my head from about 6 months ago.

Best off calling one of the guys there are getting a firm quote. They have several different grades in stock and providing you know what your after size wise they're very quick at dealing with your questions

Race tech steel 02 9680 1001.

[Gts-t]

Hey risking,

if its .5kg saved per length of 6.2m and he needs about 25m that would be closer to 2kg?

[Phobic]

hey risking sorry to go off topic here, but just curious as to what pipe bender you use. its just a standard crush bend style machine isnt it? one of my mates here reckons you madrel bend the steel.

and if you are making you own cage what process do you have to go through?

[tacker]

go bonds they do a good job and they have weld in kits for both 32 and 33's. Or you can look at design approved by the FIA in their regs which is section 253-8 which cams should have no issue with as they are an ASN of the FIA. Then have it welded by a G6 certified welder i believe ( roy might help on this one ) and you should be good to go

[Risking]

Hey risking,

if its .5kg saved per length of 6.2m and he needs about 25m that would be closer to 2kg?

In theory yes but it typically works out a little bit more because you TIG weld it which requires much less filler than MIG. per length yes you are right but over all cage would be about 4 kg once you factor in the filler rods etc used to weld it together.

hey risking sorry to go off topic here, but just curious as to what pipe bender you use. its just a standard crush bend style machine isnt it? one of my mates here reckons you madrel bend the steel.

and if you are making you own cage what process do you have to go through?

I use a speed werxs mandrel bender. You cant press bend the material and get the bends with aceptable deformation. I had an exhaust shop press bend me up a few legs but they were rubbish, so I got a proper bender, the die sets are expensive (600plus) for a pair but well worth it when you do a few. I also have a basic floor mounted press bender that is usless for cage material but good for simple exhaust tube (side pipes etc)

There are very few people who have seen my cage in depth or the way it was constructed so im not sure how your mate would know exactly how I did it??

Short on time but ill run through latter basicly what we did with my last cage.

[DCIEVE]

What are the design requirements as set out by cams - obv they set out some rules of thumb ie minimum wall thickness etc but they must also allow deviations based on detail design (analysis). Pay off for using higher grade steels is typically not worth it in structural applications due to the low inherent sf of a material with yield approaching uts being treated cautiously by the codes.

If the design is for stiffness then the saving is negligible due to similar youngs modulus. If based purely on yield strength then the saving approaches 40%....depending on the design code of course (if the minimum wall thickness, for example, is not set in stone).

Roy, there is sfa difference in density - the weight difference is due to the amount of material required to achieve the desired strength.

[BOZ22N]

Just talked to Bonds and they quoted me as per below for a kit for my R33 GTST, (bolt in only).

$869.00 for full bolt in cage including all hardware

$121.00 for both door bars

$121.00 for a adjustable harness bar

$1110.00 Total

This will be not road register able and will be easily log booked if you need it to be.

Has anyone got anymore prices?

Cheers,

Ryan

[Phobic]

has anyone got any pics of the bond roll bars? how close fit are they?

[BezerkR32]

Not sure what you drew for them, but my molly cage cost $3000. i then had an extra side intrusion bar fitted. at the end of the day you cant put a dollar figure on safety, it costs what it costs. if you want to save a couple of kilos on the way the moly is the go.

I buy my steel through racetech here in Sydney.

Their lengths can varry depending on how they were cut at the mills. However generally they are around the 6.2meter mark.

So you'd see roughly a 4 kg (over 25meters) gain in using the chromoly. Some people will argue its more but thats what I have weighed from the supplier I use. My current cage is all chromoly simply because I did all the fabrication my self so the extra labour costs were not an issue, I bent it myself so again time was no issue and welding is no problem either. The cage I did I was quoted roughly $9-12,000 by a few places (without the engineering for cams) just going off the the sketches that I showed them and the materials I wanted to be used. The same cage out of CDS mild steel was going to be roughly $6500.

Im honestly not sure what the current rate is for steel as last time I bought was in bulk before the dollar crashed.

However from memory the CDS was $28 a meter and the chromoly was $39 retail. Dont quote me on those numbers as its mearly off the top of my head from about 6 months ago.

Best off calling one of the guys there are getting a firm quote. They have several different grades in stock and providing you know what your after size wise they're very quick at dealing with your questions

Race tech steel 02 9680 1001.

[tk80]

Not sure what you drew for them, but my molly cage cost $3000. i then had an extra side intrusion bar fitted. at the end of the day you cant put a dollar figure on safety, it costs what it costs. if you want to save a couple of kilos on the way the moly is the go.

that's a cheap moly cage. any pics? who did it?

[Risking]

It is cheap.

My cage is not really anything simple. It was a bitch to build and hence the quotes as experianced cage builders know whats going to be involved well before doing the job.

[BezerkR32]

There are pics in my LS1 Conversion thread in this section. Believe me this was on the expensive side when i had it done. PRO FAB Motorsport in Wollongong did it. Mostly do ANDRA style cages.

that's a cheap moly cage. any pics? who did it?