1/2 cage rollbar - thick or thin DOM tube?

[winstontj]

Does it matter? It's mostly for looks and will go along with a rear-seat delete. Car will have stock front seats for now and simple 1/2 cage so I can get out on some more serious autox & entry level track stuff... again mostly for looks. I'll use this as a commuting & DD car in a few months.

Also how much? usually ~100ft gets you a full cage... should I plan on 50 or 75? would 3 20ft sections work? I'm thinking the thin stuff only because I can make tighter bends and in theory could keep the cage closer to the profile of the car...

Thoughts??? Should I get whatever is cheaper? Also very interested to hear how much it would take to do a rear bar/ half cage only.

Thanks - need to order within the next month or so

[bmw1602.com]

Vintage rules in my area recommend, 1.5"x.120 wall DOM

I wouldn't use anything else.

[winstontj]

1.5"x.120 wall DOM

I wouldn't use anything else.

Pedro is that the thin wall or thick wall stuff... I can't recall...

Thanks!

[Ian]

BMW club racing allows 1.5" x 0.95 DOM for cars under 2200 lbs. That's what I'm using to build my cage.

In

'76 M2

[us4736]

i used 1.75 x .095 DOM you can make bends as tight as you want if you have the right dies in the bender . all that work you might as well make legal .

[canadapierre]

More pics please!

[TobyB]

Read the SCCA rules- they're pretty consistent across class lines.

1.5 x.120 (thicker tube) or 1.75 x.095 (thinner) is, iirc, the spec for

cars of our portliness.

They also have things to say about bend radius, too (3x diameter) so

that sometimes the heavier, thicker smaller weaker tube works better.

While you're there, look at their suggestions and restrictions for base plates-

they have a lot to say, and most of it's good. Tying the cage to a 2002's

perimeter shell adds tons of strength for ounces of added metal.

Frankly, it's worth just doing it their way- it costs a few bucks more, but if you

ever want to sell the car, it expands your market significantly.

No- one wants a caged car that they're going to have to cut the

cage out of to put a LEGAL cage in! And while I don't necessarily

think that the SCCA is the final arbiter of safety, they DO have some

experience with crunched cars...

my '02.

Toby

[winstontj]

you can make bends as tight as you want if you have the right dies in the bender.

As others posted there are usually rules such as no bend radius tighter than 3x tube diameter so you can't really bend as tight as you want AFAIK... Could be wrong tho. The guy that will help me has a bender and all the dies out there... no worries on that front.

the heavier, thicker smaller weaker tube works better...

base plates...

Tying the cage to a 2002's

perimeter shell adds tons of strength for ounces of added metal.

This is going to be 99% for show and only a rear roll bar. I do want to build it so that I could expand on it later if the need ever presented itself...

Toby are you saying that the thinner diameter 1.5 x .120 is heavier and weaker than the 1.75 x .095? I guess there's little difference between the two so I'd rather put the stronger lighter in...

[TobyB]

Yep, the typical 'wisdom,' for what it's worth,

is that the bigger tube is better EXCEPT that

you can't bend it as tight.

I guess my thought is that it's not too hard

or much more expensive to make the back

half SCCA legal. Then if you do sell it,

you can sell it with an 'SCCA compliant half- cage'

t

[TobyB]

Yep, the typical 'wisdom,' for what it's worth,

is that the bigger tube is better EXCEPT that

you can't bend it as tight.

I guess my thought is that it's not too hard

or much more expensive to make the back

half SCCA legal. Then if you do sell it,

you can sell it with an 'SCCA compliant half- cage'

t

[TobyB]

Yep, the typical 'wisdom,' for what it's worth,

is that the bigger tube is better EXCEPT that

you can't bend it as tight.

I guess my thought is that it's not too hard

or much more expensive to make the back

half SCCA legal. Then if you do sell it,

you can sell it with an 'SCCA compliant half- cage'

t

[winstontj]

Yep, the typical 'wisdom,' for what it's worth,

is that the bigger tube is better EXCEPT that

you can't bend it as tight.

I guess my thought is that it's not too hard

or much more expensive to make the back

half SCCA legal. Then if you do sell it,

you can sell it with an 'SCCA compliant half- cage'

t

Thanks guys - I'll read the rules again and start figuring things out. ToddK told me to estimate 100 feet for a full "good" (meaning better than bare minimum) cage. How much should I order for a half cage? I'll plan on taking the roofline from the B pillar back to the rear window, then down to the shock towers so I'll have a little more back seat room - of course if that's allowed.

50 feet? 75 feet knowing there will be some for spare?