Roll bar

[boxhead]

Hi there Guys & Gals.

I went and saw a local engineering firm today and asked about bending a roll over hoop for me.
He asked what material I would like it made in (I hadnt thought of this), I will be making the hoop from 50mm od tube with 2mm wall thicness (should I go thicker?) I dont want stainless as I am painting the bar anyway and want to be able to weld the 3rd leg connector on myself.

[stephen low]

PM sent

Cheers

[vettestr]

Hey Boxhead,
NHRA specs for a roll bar are = A roll bar must be at least 1 3/4 inch outside diameter and have a wall thickness of at least .118" for mild steel tubing or .083" for chromoly tubing.

I offer this only as a starting point as this NHRA rule means nothing for your requirements. I make mine out of seamless chromoly 2" OD with a wall of 0.120". A material spec is 2.000” x 0.120” CDN/4130/Seamless or ASTM 1018/1026 CDS/DOM .

ERW tube is cost effective and nice to work with. Have fun Jeff C

[boxhead]

Jeff, thanks for the info.
Now to show my lack of metalurgy knowledge, can I weld the chrome moly with a standard mig welder with the normal wire?

[vettestr]

Sure, it welds nice. We use argon most of the time but 95/5 or C02 works great.

[vettestr]

You might want to check out the mild steel and not the c moly when you see the price.

[boxhead]

Thanks for that Jeff

[Chrome]

Hi David
This is from the Cams Rule book;

A solo roll bar, the main hoop need to be made out of 44.45 x 2.5mm wall thickness or 50mm by 2mm wall thickness.

The material has to have a carbon content of 0.3% maximum Manganese content of 1.5% max other alloy content 0.5% for any element Max. Tensile strength 350 MPA minimum.



The Andra rule book;

1 5/8 by 2.9mm or 1 ¾ by 2.6mm Mild Steel for a main hoop.


Hope this helps?

[stuartt]

I'm pretty sure mine is 50mm x 3mm and came from snake bite.
Stuart

[ac andy]

Hi Boxhead, i just had another hoop rolled at Bendtech in Clayton, Melbourne. Mine is stainless but their opinion was that the greater the wall thickness, the easier it is for them to bend without creasing it. I used 50mm x 3mm stainless steel and it rolled out beautifully.

Andy.

[Rob. Smith]

G'Day Boxhead,
Bought a chrome molly Bar,bent to suit an rmc 50.8 x 2.5 on a 152mm radius. . . cost me $285 strut brace included. I have to sort the angle and fish mouth the brace myself. ( they can do it if you have the correct angles etc)
Carrington Products 22-26 Melbourne street Riverstone NSW 02 9627 4277

[hogster]

Hi boxhead,

I'm going to run two hoops, 2 inch od with 3mm walls and the rear stays as well. When I lap sprint I am going to clamp them together on the inside of the hoops. In my line of employment I have learned that skidding on your head is extremel unpleasant.

Have a friend who recently purchased some serious tube equipment so we should be able to work something out for the extras.

Hogster

[727pilot@usa.co]

One of your mates on this forum made this roll br for my project. It has been powder coated and looks great. Note that the right back leg is not in it's socket in this picture.


http://homepage.mac.com/tlempicke1/C...r/large-1.html