Rollcage Dimensions - Post yours here

[RyleyMA61]

I am going to be putting a rollcage into my MA61, and to save on fabrication costs, I hope to use the main hoop from another vehicle and adapt the rest from there.

If this thread became a reference for main roll hoop dimensions I would imagine it'd be a valuable resource to other forum members who are interested in doing the same for many different sorts of vehicles!

So if anyone who has a cage can post up the following dimensions, that would be great!



H =
W =
h =
w =
X =
R =
Theta =
Phi =

Cheers,
Ryley

[wilbo666]

Brett should have the dims for MA61 I think

Cheers
Wilbo

[Bananaman]

I can do this for my car, but I have no idea how to measure the angles you are after.. i don't even have a high school protractor

ed: Measuring R looks hard to do accurately as well..

[hypo23]

to get the r angle a 2 foot folding rule with a line of chords on it will do the job nicely

[RyleyMA61]

R probably isn't a big deal

Even just all the distances would be helpful probably! Instead of the angle measure the length of the curve perhaps?

Thanks all!

[brett_celicacoupe]

nah dont use my dimensions. it wasnt a very close fit

[hypo23]

after looking at the pic again, your right angle r is not really important as its only the radius of the bend, but what a line of chords rule will give you is the actual angle of which the bend has to be which is kind of important if you want a nice tight fitting cage

[brett_celicacoupe]

2 things to add here.

- r is dependant on the die used in the bending machine.
- the pipe is usually bent based on length that doesnt stretch. typically the neutral axis is on the inner edge of the pipe, not the centreline based on how the pipe is bent.


ie someone bending would probably scribe a straight line and then centre-pop the starts of the bends on the inner edge

[RyleyMA61]

yeah thanks guys, id thought of that... im really just trying to get a database of main hoop sizes out there so that we can save on manufacturing costs and use more common roll hoops rather than getting custom all the time

going to measure an s13 and vl one soon and ill bang them up

[.T.]

having worked for a motorsport business that did roll cages (i think) qualifies me to put my $0.02 worth in here.

Your cage design will be dependent on 2 main things -
1. is the cage a bolt in or weld in? as cage design will vary dramatically
2. road legal? as requirements vary from state to state.

44mm for main hoop, 38mm for pretty much everything else.

if you want a "kit" cage try bond rollbars - they do bolt-in "kits" (lots of work to fit). they will have a number of hoops you can buy

[RyleyMA61]

thanks mate, i've heard of bonds.

i know them ain roll hoop can't be welded, and must be a singluar piece of steel, but can other bends be welded etc?

cheers
ryley

[Lachie]

having worked for a motorsport business that did roll cages (i think) qualifies me to put my $0.02 worth in here.

Your cage design will be dependent on 2 main things -
1. is the cage a bolt in or weld in? as cage design will vary dramatically
2. road legal? as requirements vary from state to state.

44mm for main hoop, 38mm for pretty much everything else.

if you want a "kit" cage try bond rollbars - they do bolt-in "kits" (lots of work to fit). they will have a number of hoops you can buy

Don't forget about the wall thickness on the tube, and the alternate sizes. The sizes you can use if your going if a CAMS spec cage are as follows:
44.45 x 2.5mm OR 50 x 2.0mm for the main hoop
38 x 2.5mm OR 40 x 2.0mm for all the other bars

Grab yourself a CAMS manual and have a look at Schedule J. Read it, read again, then keep checking it as you design your cage. Of course, if you are really chasing wieght, you can through the CAMS specs out the window, design your own cage and go through the certification process. That will probably cost you couple of grand though, with all the FEA work involved and a company siging off on it. To give you an idea of the wieght saving, we are currently building a cage at work that has about 80m of tube and wieghts 30 odd kg's. My cage built to cams spec has about 14m of tube and wieght about the same. Reason being is you can use mush thinner tube if you go through the certification process i.e. the main hoop in the cage metioned above is 1.0mm, but a higher grade of steel.

Also, why adapt a hoop from another vehicle? I paid 80 bucks for a chassis mob to bend up a main hoop, lateral roll bars and a windscreen bar. For that sort of money why mess around trying to use something out of another car, just get what you need from someone who already has a template for your car.