Rods 'n' Sods - UK Hot Rod & Street Rod Forums banner
1 - 15 of 15 Posts

·
78 Bronco BRING IT ON!
Joined
·
440 Posts
Discussion Starter · #1 ·
I`d like some pointers in selecting the right size and type steel tube to make my roll cage out of.It`s for my Bronco and my intentions were to make a hoop for behind the front seats with braces going into the back and then a leg each side going from the top of the hoop across the top of the door down the a pillar to the floor. Finally a brace across the top of the windscreen.I am led to believe the seamless tube is incredibly expensive, so what other choices do i have. I have a hydrolic bender which will bend up to 2" tube so what thickness tube will bend best without creasing. Lastly when cutting out the half rounds at the end of each tube is that done successfully with a hole saw and careful measurment? I`m sure there must be dozens of tips those of you that have done this before can share and i`d be very greatful to hear them. Paddy
 

·
Registered
Joined
·
2,135 Posts
1 5/8" 3mm wall CDSII tube.
Yes its seamless and no its not incredibly expensive.
Its the only tube that is the correct grade for roll cages. (except for more esotoric tube of course).
Hydraulic bender wont bend it though (it will collapse it), you need a mandrel bender.
Not strictly true Mark. A "bow and arrow" type bender will bend it to a point, and then it will fracture(unless it is hydraulic as opposed to mechanical tubing) or the wall will collapse.
I agree though, for anything with more than 40 degree bends a mandrel type is the way to go.
Paddy, don't even consider ERW tubing.
 

·
Registered
Joined
·
1,500 Posts
The first question is do you intend to do any type of competition?
If you do get a rule book from the organisers and follow that.
The spec mentioned is good for drag racing but not for other motorsport. Drag racing uses a US rulebook but most UK motorsport uses the MSA blue book which specs inch and three quarter tube with a 2mm wall (from memory). The main issue you will face if it is for competition is tying it into the chassis which will probably require outriggers welded on the main rails. Plating it to the floor on a chassied vehicle is frowned upon as the body can depart from the chassis should the worst happen. Neil.
 

·
Premium Member
Joined
·
7,639 Posts
hello paddy
like the others have said it depends what you want to do with it.

cds if now cfs and the correct grade is bk as drawn.
if you read the specs for racing its the only cfs that has the correct yeild strenth.
its also the cheapest.

not sure how anyone would ever know though if you used the wrong spec tube.grade not thickness

local 4 x 4 boys use gas barrell for a lot of there cages and rolling down hills doesnt seem to do it any harm.

kinda dissagree with the erw coment again though depending on application.
road car just for looks youde have to have some hefty crash to split the tube and if you did im sure youde be brown bread anyways.

beleive some roundy roundy cars are built using erw.

cfs vary,s in price.look at around £6 to £7 a metre for 1 5/8 ". though it is a pig to bend with wrong bender.
 

·
Got salt
Joined
·
1,305 Posts
Funny enough, I was just ordering CFS3-BK tube today, including some 1.625 x 10g. Hub tubes want £6.58 per metre and Multitubes want about £9.
You dont need a mandrel bender, a non-mandrel rotary draw bender will do it too.
ERW isn't as rigid as CFS because it isn't drawn, but theres nothing wrong with it and it doesn't split. Hollow section is a different matter. The 2 are often comfused.
 

·
78 Bronco BRING IT ON!
Joined
·
440 Posts
Discussion Starter · #7 ·
I`m getting a bit confused with all these abreviations. I want it for playing in the mud and off roading for fun rather than competition, at the moment that is.I need tube that i can bend on my hydrolic benders,I want to make tube bumpers and crash bars.Of course a tube that ticks all the boxes would be great.I do`nt know what a mandril bender is, or the difference between them. There must be a compromise or perhaps not.I must say that if i`m going to the trouble of making it i would like to make it right. As far as fitting it to the chassis or not, i`m quite happy with it just fixed through the floor.The frame that strengthens the floor of the body is heavier than any monocoque vehicle i`ve ever seen as standard.
 

·
Premium Member
Joined
·
7,639 Posts
45(1 3/4") x 3mm erw.
id try to get an off cut first to try in youre bender.
im sure hydrolic bender die sizes relate to internal pipe sizes so you may need to use the 1 1/2" die to bend the 1 3/4 tube


if youre mounting direct to floor weld some 3mm plates to the floor first to spread the load
 

·
78 Bronco BRING IT ON!
Joined
·
440 Posts
Discussion Starter · #13 ·
I put this one on the other channel recently,
shows tube specs, bender and tube notcher pics.
http://www.nsra.org.uk/newforum/showthread.php?t=26431&highlight=cage
Thanks for showing this thread.It answers a great deal of questions for me.What you built there is very much the same as i`d like to.The tube notcher also answers a bugging question.The bender i`ve got I now know to be a bow hydrolic bender like yours.So to clarify, can I bend the right kind of tube for making foll cages on my benders or will I go with tube like you have used in the 34. Nice touch with the wheel nuts, they worked out well. For future plans i may have, what are the rules on what type of tube works in my benders and what does`nt :S
I have to say the Grannada chassis in the photo just looks like a confusing pile of tube! The photos do`nt do it justice
 

·
I'm a grown up drunk!
Joined
·
2,677 Posts
Thanks for showing this thread.It answers a great deal of questions for me.What you built there is very much the same as i`d like to.The tube notcher also answers a bugging question.The bender i`ve got I now know to be a bow hydrolic bender like yours.So to clarify, can I bend the right kind of tube for making foll cages on my benders or will I go with tube like you have used in the 34. Nice touch with the wheel nuts, they worked out well. For future plans i may have, what are the rules on what type of tube works in my benders and what does`nt :S
I have to say the Grannada chassis in the photo just looks like a confusing pile of tube! The photos do`nt do it justice
The 'bow n arrow' type bender used to do the 34 will only realistly bend the seamed tube used on the 34, tried CDS years ago on it, waste of time,

the formers on these type benders are measured by I/D, so dont relate to the external tube diameter, it'll still bend it but as the tube is loose in the former it'll come out a bit egg shaped, you need to make a reducer,
real easy, simply a piece of around 20 guage sheet steel around 15" x 4"?,
bend a test piece of tube so that it moulds the sheet to suit the inside of the former, you only need one, it's reusable,
technically, no this isn't the best tube for a cage, but a LOT safer than a car without a cage,
as an example, a guy imported a pre bent cage a few years back that i installed in an early Barracuda, came from one of the big US suppliers, alston? morrisons?
recommended for an 8-9 second car,
what was it made from? regular seamed tube!
what a waste of expensive shipping,

if you want to use the bender you've already got you'll need
CHS 42.4mm o/d x 3.2mm tube, comes in around 7.5m lengths,
i use FH Brundle for mine, about £25 per length last time i got some,
theres a branch near you in Southampton, and they deliver,
hers a link; http://www.fhbrundle.com/sect-05.htm

i you choose to go the better CDS route,
or the even better 4130 chrome-moly route you'll need a bender like this,
one that supports the complete diameter of the tube while bending,
you'd probably need to farm it out to a chassis shop.
good luck:tup:
 

·
78 Bronco BRING IT ON!
Joined
·
440 Posts
Discussion Starter · #15 ·
Thank you so much for spending the time on explaining this properly, it really is very good of you.I now have it clear in my mind what`s what.If i build a seamed tube roll cage and need to upgrade it later I could allways use it as a template,i`ll have to double check on the all wheel drive clubs requirments.I hav`nt joined the club yet because the trucks not been ready, but i can ask a mate.Cheers again
 
1 - 15 of 15 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top