Roll cage problem

[ho428]

This is a race car and has to meet some rules.
Back tubes can have no bends, back tubes must be no less than 30 degrees.
That makes them run outward and right into the bulkhead. See pics.

This is by the SCCA rule book. But I'll be running HSR and NASA which doesn't really have one. I was told to go by SCCA and it would pass anything. One regular in HSR said to run them back the way I had them, (sorry no pic) but they were in the corner of the main hoop and ran straight back at about 25 degrees,

Am I missing something?

[shizzy]

I dont understand the question/problem.

[MrQuick]

NASA does have a rule book, I believe it is available on line too.

I would just followthe SCCA rule and change you cage accordingly. Not a big deal if you haven't fully welded it yet.

To be sure, tack everything and trailer it to an event for inspection.

[ho428]

I finally got to talk with the Techs from NASA and HSR and sent them these pics, both said the way I had it previous to the pics would be fine and actually better. The back tubes were run all the way to the spring perches and were straighter in line with the Halo. They said they don't worry so much about the degree as SCCA does, more about the overall design.
You can see the cut out closer to the back windshield, that's where they ran through the package tray before we moved them to get 30 degrees. I'll move them back and weld in some patches.
They did say I needed to raise the cross bar some, it's only tacked so that's easy enough. I hadn't cut the diagonal yet.

So far I'm having a blast designing it, but the shop was moving stuff without me knowing so I had to try and get answers fast.

[roadracer55]

funny you should mention cross bar - I had to move mine up after seeing this pic and comparing where my seat was positioned. dont forget to plan the belts at this stage too..

https://static1.pt-content.com/images/noimg.gif

[scotzilla]

alot of rules are open to inturpitation and it also depends on who is teching your car- I had a drag car fail cert last year due to a bad piece of chromoly- THe rest of the build was picture perfect- weld looks flawless- THen i saw the same inspector pass several cars with obvious problems if they promised to fix them and send him pictures- Yet he wouldnt do the same for me- Its all in who you catch and what kind of mood they are in

[ho428]

Cage is pretty much done, I've got a little more welding to do.
I thought about adding another brace where the tape is, from a design point it looks like it would really brace the back bar, but I've never seen anyone put one there. Must be a reason.

I guess this can be pulled from the emergency room now.

[wendell]

Hey man,
cage looks great. Got a picture of the driver's side door bars?

[Speed Raycer]

I thought about adding another brace where the tape is, from a design point it looks like it would really brace the back bar, but I've never seen anyone put one there. Must be a reason.

That bar wouldn't really do a whole lot... dead load path. If you ran it back to the rear brace mount, then you're transferring some load somewhere.

In my experiances, the NASA rulebook is the more specific/restrictive over the SCCA... even moreso now that the SCCA rewrote their cage rules for '08. The 30 deg. rule is in relationship to the hoop from vertical. You more than cleared that rule :D

Nasa actually has a rule limiting you to 105 to 75 degrees when viewed from the top of the hoop... which eliminates the guys using an X for their rear hoop braces and forces them to use 2 single braces.

I like your new tube placements better than the first pics. Load Paths/single nodes are your friends :D

[MrQuick]

Excellent points Scott.

Here is the rule book. Im not sure if he has found it or not.

http://www.nasaproracing.com/rules/ccr.pdf