Roll cage specs

Guys....need your input before we finish the cage. We have run the rear half with 1.75" x .130" DOM. We are now working on the front halo and downtubes, driver side "NASCAR bars" and front tie-ins through the firewall and to the shock towers.

What OD and wall thickness is allowed per NASA/AI rules for the rest of these tubes? Do I have to use 1.75" x .125" or .095" everywhere? I want to be safe obviously but don't want to add unneeded weight too.

Driver door/cage will look like this:
http://www.corner-carvers.com/forums...achmentid=8385
http://www.corner-carvers.com/forums...achmentid=8386

Also, we're adding a GM button style window net attachment (mesh not coarse net) that allows the mesh to fall rather than be flipped up. Passenger side is "X" braced. We will also have 2 horizontal bars (1 at top of dash level and 1 at or below steering column)...will mount an aluminum panel for gages, switches etc.. Bars will tie-in from front halo down tubes to shock towers. Can/ should the bottom bar be above or below the steering column?

Any other words of advice before we start welding?

thanks
Chris

Not an "official" interpretation but was the ruling I got....if the car weighs less than 3000 lbs without driver and fuel....the ENTIRE cage can be 1.75'x .095"....mine is.

And whether it be .095" or .120", for the REQUIRED bars, they all have to be the same.

Just got back from the builder. We're going with 1.75 x .130 everywhere. Yes, it'll add weight but the last thing I want to worry about a split second before any impact is if the cage is strong enough. Thanks for the info guys.

Now I just need to find a set of 17 x 9 5-lug rims.... :D

Here's a few pics of the new cage that we finally finished. We're pretty pleased with the design and the overall fit/finish. If anyone needs a custom cage put in and you don't mind a bit of a drive these guys do excellent work for a fair price. We decided to go with 1.75" x .130" wall DOM everywhere. A few added last minute bits were the cage-to-strut tower-to-frame pieces which are also 1.75" x .130 DOM. Next on the list is to mount the seat, harness, window mesh and dash/gauges etc. Will update with pics once they are installed.

Chris

http://www.myweb.cableone.net/prodigydesign/cage1.jpg
http://www.myweb.cableone.net/prodigydesign/cage2.jpg
http://www.myweb.cableone.net/prodigydesign/cage3.jpg
http://www.myweb.cableone.net/prodigydesign/cage4.jpg
http://www.myweb.cableone.net/prodigydesign/cage5.jpg
http://www.myweb.cableone.net/prodigydesign/cage6.jpg

What I learned the hard way was that everyone who posts on the internet is stress analysis engineer, master fabricator and metals expert.

While I'm sure you are very proud of your progress and I am happy to see your progress, posting pictures will lead to some serious anxiety and gnashing of teeth.

Everyone has "your best interest" at heart. :roll:

Having said that ...

Congrats on the progress and hope to see you on track soon.

I am going to send an email to Richard P and have him look at the photos, but I don't think the rear section will work within the rules.

David D.

Chris,
I'm worried about your rear down bars. Per CCR Sect. 15.6.11 the rear braces must start no further than 6 inches from the top of the hoop and not contain any bends.

You may want RP, AG, or TC to comment as well.

Chris - please contact me as soon as possible to discuss cage construction.

Email is http://www.shrackracing.com/email.jpg, or call my cell ( you should have the number ).

Although not what I wanted to hear, this is why I posted them....for critical review. Now is the time to catch items like this and correct them before arriving at an event. Adam- I'll be in Dallas this weekend and next week....call me on my cell when you get a minute.

thanks
Chris