Well as an ended of the year project in my auto class. So i got some of the tubing today. it is cromally 1 3/4" and .095 wall. i was told the standard is 1 5/8" but they didn't have that size where i went. I was wondering with an angle for example 90 degree angle what radius would the bend need to be to keep its strength? And other than that any good links to info on design of roll cages or i guess its considered a harness bar if it goes from the front seats back. thanks for the help

 

Your gonna need the 1 5/8 to make the main hoop, d bars, back bars, etc. the rest of the cage you can use 1 1/4 for supports, seatbelt bar, etc. Atleast thats how i did mines.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SuperSpic &raquo;</TD></TR><TR><TD CLASS="quote">Your gonna need the 1 5/8 to make the main hoop, d bars, back bars, etc. the rest of the cage you can use 1 1/4 for supports, seatbelt bar, etc. Atleast thats how i did mines.</TD></TR></TABLE>

why can't you use 1 and 3/4 inch tubing? it's just slightly bigger than 1 and 5/8.

 

just look at a basic design like a autopower rollcage and build something similar to that. I think a rollbar is what you were trying to refer too not a harness bar btw.

here is link to autopower rollbars:
http://www.autopowerindustries.com/rollbars.asp

 

you can use 1.75" diameter dont worry.
build the cage to a class rule set and youll be good.

use a radius that your bender has.

 

I came up with design that is similar to those but a little more extensive. but yeah i guess it would be considered a roll bar. is it stronger for the piece that goes from the passenger floor to the driver side roof to be split and welded to the bar that goes across the middle or is it stronger if the bar that goes across the middle bends around it so that the bar is not cut and welded? if that makes sense.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dfoxengr &raquo;</TD></TR><TR><TD CLASS="quote">you can use 1.75" diameter dont worry.
build the cage to a class rule set and youll be good.

use a radius that your bender has. </TD></TR></TABLE>

how do you find out the class rules? also now i'm hereing bad things about cromally like it can shatter under a lot of wieght. is this true? do i have to worry about it not holding up if the car rolls over?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mike03,95civic &raquo;</TD></TR><TR><TD CLASS="quote">I came up with design that is similar to those but a little more extensive. but yeah i guess it would be considered a roll bar. is it stronger for the piece that goes from the passenger floor to the driver side roof to be split and welded to the bar that goes across the middle or is it stronger if the bar that goes across the middle bends around it so that the bar is not cut and welded? if that makes sense.</TD></TR></TABLE>

this issue is addressed in the rules of whatever racing youre going to be doing, if any.
never bend that tube around. cut/notch it, but the issue is whether to have the diagonal 1-piece, or the harness bar 1-piece.
youll have to check the rules for that.

as to which set of rules. what kind of racing if any are you planning?
if none, then Id build to NHRA specs

 

i agree,,also look a SCCA rules

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dfoxengr &raquo;</TD></TR><TR><TD CLASS="quote">

this issue is addressed in the rules of whatever racing youre going to be doing, if any.
never bend that tube around. cut/notch it, but the issue is whether to have the diagonal 1-piece, or the harness bar 1-piece.
youll have to check the rules for that.

as to which set of rules. what kind of racing if any are you planning?
if none, then Id build to NHRA specs</TD></TR></TABLE>

so you wouldn't bend the tube at all, or are you saying only for sharp bends?

I plan on trying out both autocross and drag. don't know group i would race at. I know SCCA is in california but what other ones are here in california? i looked up the SCCA rules and it said the only material allowed is mild steel or alloy tubing (SAE 4130). I know cromally is an alloy so i'm ok on that part right?


Modified by mike03,95civic at 6:28 PM 5/14/2008

 

yes youre ok.
make the tubes intersect, anything else is bad. (ie. bending it away so they arent in the same plane)

 

NASA is in so cal

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by b16_DIM &raquo;</TD></TR><TR><TD CLASS="quote">NASA is in so cal</TD></TR></TABLE>

thanks. do you know if they ever have them at el toro?

anybody else knows other classes let me know.

 

I don't know the autocross schedule. You can check it out at http://www.nasaproracing.com Redline also does local events but I'm not sure what their url is.

Nasa races at California Speedway once a year and all other events are at willowsprings and buttonwillow (lancaster and bakersfield). I'm thinking about making my first cage next year so let me know if you are interested in working together on it.

 

well the process is under way. i'm going tomorrow to pick up the rest of the tubing and hope to have it finished by the end of the week. thanks for the info everybody. when i finish it i might put up some pics up here.