So I have done some research but am still unsure about this...

I am not sure which size tubing to go with... for H1, my weight w/ driver is 2200lbs, I weigh 160... so IDEALY my car should weight a little over 2000lbs empty. I am not sure exactly what the car sits at now. So should I go with the:

1501 - 2200 lbs.
1.500” x 0.095” DOM/Alloy/Seamless

or the 2201 - 3000 lbs.
1.500” x 0.120” DOM/Alloy/Seamless
1.750” x 0.095” DOM/Alloy/Seamless
to be safe?

if i should go with the 2201-3000lbs range... does anyone know which size tubing weighs less per foot?

sorry if this has been covered, i did a quick search and could not find anything... cage goes in this week!

 

My math (if its right) says the thinner walled, 1.75" tubing will be lighter. Based on surface area calculations of a cross section of both tubing sizes, the larger diameter tubing would have a surface area of .4939 square inches, whereas the 1.5" would be .5202 square inches or about 5% more metal in the tubing.

 

My 1993 Civic coupe is well under 2200 lbs. This is with 1.5 X .095 tubing except for the rear stays (was running out of tubing ) which are .120 wall.

 

Jaker's math is A-ok...and I suck for checking it.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Jaker &raquo;</TD></TR><TR><TD CLASS="quote">My math (if its right) says the thinner walled, 1.75" tubing will be lighter. Based on surface area calculations of a cross section of both tubing sizes, the larger diameter tubing would have a surface area of .4939 square inches, whereas the 1.5" would be .5202 square inches or about 5% more metal in the tubing.</TD></TR></TABLE>

right on the money

the weight difference is negligible.

 

For our CRX (H4/ITA) we elected to use 1.75"x.120" DOM. The cage is a full 8-point with NASCAR door bars on the driver's side. The total weight of the cage as shipped from KIRK was 135 before it was welded in. Why so heavy-because my fabricator is a safety nut. It is true that you can go with either a thinner wall or diameter (see rulebook and decide). The weight savings will generally come only with Chrome Moly tubing-and that stuff is not easy to weld properly.

 

(wrt cage tubing sizes per weight) SCCA (would think NASA too ??) talks about car weight without driver so it might be effectively lighter than you are concerned.


Modified by phat-S at 10:05 AM 12/27/2004

 

A correction: within SCCA's Improved Touring, for the purposes of rollcage construction, weight is as published minus 180 pounds (18.1.6.D, p 115 in '05 regs).

However, NASA CCR specifies rollcage tubing size for vehicle without fuel and driver (a nebulous number of there ever was one. A fatboy could build a thin-wall cage, where a horse jockey has to use thicker tubing. Yet both cars weigh the same when they roll over...)

Since your H1 legal weight is 2200, you would need to construct your car to the "1501-2200" specs, which is 1.50x.095 minimum.

I don't know your car, but you're H1 so I'm guessing an ITS capable Integra GSR or a Type R? If you decide to run SCCA your 'rollcage weight' will probably fit in the 2201-3000 range, which requires 1.50x.120 or 1.75x.095 minimum.

Given all this, it's in your long-term best interest to build the cage to the tighter SCCA specs. Even if you don't race SCCA, by having an SCCA-legal cage you can sell it to someone who may.

Some thoughts:
- 1.75x.095 is lighter than 1.50x.120
- 1.75x.095 is stronger in bending than 1.50x.120 because of the diameter (walls are farther apart, thus resist the tension/compression forces better)
- While the weight difference between the two may be considered "neglible" per foot, multiply that difference times the number of feet you're going to use on your rollcage. No easier or better way that I can think of to lose poundage above your center of gravity...(hey, it all adds up...)

Tubing weight can be calculated by:

W = 10.68 t (D-t)

where:
W = weight (lb/ft)
t = wall thickness (in)
D = outside diameter (in)

Have fun!

 

I thought he had a hybrid motored Civic (jellybean style) if its the car they had at Road Atlanta (???). I am not sure if the car itself (could be ITA or ITC I guess natively) could probably still be sub 2200 lbs. sans driver (or the corrected 180 lbs. you point out - I am looking at a 03 GCR w/ the "without driver" line).

 

Always build a cage legal for every sanctioning body that has a class for your car. If SCCA specs are tighter than NASA specs, build to SCCA.

As Greg mentioned, if one day you decide to sell, it will help.
And tearing out a welded cage kinda sucks. Might as well toss the chassis and start over.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Catch 22 &raquo;</TD></TR><TR><TD CLASS="quote">Always build a cage legal for every sanctioning body that has a class for your car. If SCCA specs are tighter than NASA specs, build to SCCA.
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Bah! Maybe when the rules between the two bodies were closer but if I already had a motor/tranny, suspension bits and brakes that put me in HC H1, I'd attach the cage to the chassis since its allowed.

Now if the car was H4 to begin with, might as well take the hit on rigidity to allow yourself to run between the two but if I was putting a hybrid motor in the car and big brakes ... I'm going to first go nutty w/ the cage (and I am not sure that thicker tubing or thicker wall is the best way to do that for its weight - but I am not a cage builder so I don't know) and attach it wherever I could.

 

smaller diameter tubing may weigh a little less , but you cant get as tight of a radius when you bend it.

I always opt for 1.5" when I can , you can get the bends so much tighter to the car itself.

vision is good.

bars away from head is good.

 

run cromo per foot it weighs the same in the same wall thickness and size ect but it's 40% stiffer oh but buy your own fab guys like to claim it's 700 bux for materials when really it's less than 200

 

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

Bah! Maybe when the rules between the two bodies were closer but if I already had a motor/tranny, suspension bits and brakes that put me in HC H1, I'd attach the cage to the chassis since its allowed.

</TD></TR></TABLE>

Use tabs than could be cut out if needed... Maybe???

I dunno. I just see a whole bunch of race cars for sale lately, especially Honda Challenge. I'd want as big a target audience as possible.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sans &raquo;</TD></TR><TR><TD CLASS="quote">run cromo per foot it weighs the same in the same wall thickness and size ect but it's 40% stiffer oh but buy your own fab guys like to claim it's 700 bux for materials when really it's less than 200</TD></TR></TABLE>

run chromoly? i beg to differ...

if i remember correctly from the GCR, cars registered w/ SCCA post-01 JAN 03 won't be allowed to use alloy steel for roll cage fabrication. after 01 JAN 08, the use of alloy steel for cages will be completely prohibited.

 

Hunter, I built my car for the lighter weight class, but doing it over again, I'd choose the heavier.

This will give you, or any future purchasers, more flexibility as far as engine choices. I haven't read the rules lately, but I believe the sub-2200 specs would effectively prevent you from ever running a K-series in the car. This could be an issue somewhere down the road.

 

thanks fellas...

i'm pretty sure i'm going with the 1.5x.120. my cage builder has a lot left over from a buddy of mine's cage he just got finished doing. cage goes in wednesday!

anybody know how the box structure mounting plates are done? I really like this design over a plain flat mounting plate. do they just build a box structure and mount the bars on top, or do they go inside of them somehow?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Hunter &raquo;</TD></TR><TR><TD CLASS="quote">
anybody know how the box structure mounting plates are done? I really like this design over a plain flat mounting plate. do they just build a box structure and mount the bars on top, or do they go inside of them somehow?</TD></TR></TABLE>

I personally don't like the box style, I think you loose the ability to gain strength from the rocker panels for the most important contact points of the cage.

 

many builders do this as a way to weld the top of the cage and then lift it up to fit the roof

unfortunately if you look at it the box is vertically oriented laving room for considerable flex leading to and off kilter or seperated cage in the event of a serious roll over

plus it looks stupid

 

If the boxes or perches are done correctly, they will utilize the rocker panels. The resulting square structure will in fact be stronger than the 'L' shape of the traditional floor plate mounting method - even with incorporation of the rocker panels. Think about it.... You are taking the 'L' & adding another 'L' on top. This will eliminate the flex that can result. In addition, you are closing off the ends which further reinforces the structure.

What you don't want to do is fab a perch without a added bottom. If you do that, you create a 'cookie cutter'.

 

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

anybody know how the box structure mounting plates are done? I really like this design over a plain flat mounting plate. do they just build a box structure and mount the bars on top, or do they go inside of them somehow?</TD></TR></TABLE>

in the welding/fab forum there is a decent thread about cages and different things like boxs. Jamie has exlplained alot of stuff in it, check it out

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by civicrr &raquo;</TD></TR><TR><TD CLASS="quote">... If you do that, you create a 'cookie cutter'.

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Do you know if there's a way of visually checking to see if you have the "cookie cutter" or it there is an added bottom? I've been wondering if I have that's what I have.

 

Not really. I guess you could go from under the car & drill a small hole. If the metal is pretty thin, it is most likely just the floor pan.

What I like to do is have the bottom extend out past the verticles sides. The verticles then weld onto the plate.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sans &raquo;</TD></TR><TR><TD CLASS="quote">many builders do this as a way to weld the top of the cage and then lift it up to fit the roof
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An option to this and still have the same result is to remove the roof section. I'm not a cage builder but it looked to me like doing this gave him quantifiably more access to the top joins and he got 360 ° welds on all the stuff on the roof line and elsewhere. It might cost you a few bucks to have the roof re-spotted but I'd think for what you gain (or not lose) for doing so, its worth it as a car owner. We also removed the doors, took out the windshield (req'd for the roof removal), removed the rear windows and hatch (also req'd for the roof removal).

I think I understand what Mike Q. is saying about the box structure over a reinforcing plate but I wonder if that is actually better than mounting the tube straight to a plate as there is no hollow area below it to allow movement. But there might not be any movement, I'd think it really comes down to design. I would say however that if your cage builder is looking for you to come up w/ a means to do this, perhaps he/she is better off doing what they know to be stronger than doing something they are unfamiliar. I dunno.

JeffS, is the K-motor weight limit greater than 2200 lbs. minus driver and fuel?

 

brought the car back today... i am VERY pleased with it!!! i spent my whole new years eve afternoon/evening painting it.









bling!