cage construction
 

I'm just planning things out since summer is right around the corner and im looking into a cage.
Now, my rule book says that cars over 2500lbs have to use a 1.75"x.120"
And cars lighter then 2500lbs can use 1.50"x.120"

I know FC's can get pretty light, and even though I may weigh more then 2500lbs right now, if I got really serious about racing, I could always make my car lighter.

What im asking is should I go with the 1.5"x.120" because I can make my car lighter in the future? What is required to make the car less then 2500lbs?

I'm only doing autox/time attack stuff right now and a cage is not required. But I need one because of the chassis benefits and because I have done an engine swap and lost a little of the structure and a cage would really help tie thigns together.

read this thread

https://www.rx7club.com/race-car-tech-103/lightest-rx-7-race-car-weight-exclue-tube-frame-511087/

SCCA rules for Prod and GT classes.....

1500-2500-1.5"x.095
over 2500- 1.5x.120
1.625x.120
1.75x.095

It looks like IT uses the higher specs for 2200-3000 lbs :wallbash:
NASA seems to follow the latter

Personally, I'd play it concervatively, as you don't want to be in the position of having to re-do the cage if the car's too heavy, or having to spend lots just to make weight to get the cage legal. It'll also be slightly stiffer and safer with the larger tubing, and safety's not an area to skimp on.

If I were doing a cage for myself I'd gladly sacrifice weight to get a really beefy cage.

Just because you can make the car weight a certain amount doesn't mean the rules for the class you race in will allow you to bring it down to that weight. If you're building an ITS car it will need to weigh 2680lbs minimum and be caged accordingly. Race cars are highly specialized animals. You need to decide right now what class you want to run and how the car will be constructed. The cage will be built accordingly. Further, make sure you have a current copy of the rules you're building the car to. The SCCA GCR is now available on line. NASA regs follow the SCCA regs closely. IIRC all new cars must be built with DOM tubing so that will narrow your tubing choices.

Latest tests by some rally teams have shown that smaller diameter/thicker wall tubing will defrom more before it buckles. This adds just a little bit of weight, like 2/10's of a pound per foot, but they feel the extra deceleration time in an impact is worth it.
I have seen many cages after crashes and the top coming down is the least of my worries. I look at side protection for the driver as THE most important thing.
I probably will do the next cage with the smaller size tubing if I have the option.

Interesting comment about tube size. Do you have any references to these tests? I'm not doubting you, I actually would be interested in reading them.

-bill

There was a great article in the Feb 06 issue of Racecar Engineering(Vol. 16 No. 02). It goes into the side impact issues of rallying and having to protect both driver and co-driver.

Which sanctioning body? and is this for a track day car or are you actually building for a specific class?

If weight is that important to you, I'd suggest getting it down as much as you can now, so that you know if those extra bars that you want to throw in are going to hurt you or help you...

Of course, if you're that concerned about weight, look into an Alloy cage if it's allowed and they give a weight break for it.

If you need a builder, St. Louis isn't THAT far ;)

This is just a track day car. my FC has a s2000 engine in it, what other race other then autox/soloII could I run?

heres some pics of the project:
https://www.rx7club.com/other-engine-conversions-non-v-8-118/your-going-hate-me%3B-but-9000rpm-496149/

just a question, but as for construction, can you have someone do a 4 point system, and later come back and weld in the other braces for a 6 point setup? My car will only be doing some local time trials and hill climbs, so only a 4 point is required. Just a thought, since i know a decent 6 point cage is not cheap

Maybe I a little confused. If you are planning to run ITE later in the future, you will have to build a car to meet your particular region specs. Here in Or/Wa regions, car must have engine block that the car came with. Not a transplant from another manufacture.

Our ITE says must meet or exceed IT cage rules. If GCR says IT RX7 weighs a certain amount then that is the minimum spec you need to use for the cage. All the ITE cars I have constructed use the GCR for IT cage prep, not actual car weight after we have gutted it to its minimum weight. ITE cars do weigh before or after the race so the techs are not going to ask you each and everytime they tech the car.

I am pretty sure you will be using 1.5"x.120" DOM for your minimum tube size. I do not have my GCR here to check the spec in the appendage for that particular car. I do know some other organizations will allow transplant engines and what not, but you will have to check with the appropiate tech's.

Good luck!

yeah, it doesnt look like i can run anything other then auto-x or, maybe some unlimited class with this car. I guess i should get this car to where I want then weigh it to see where i stand.

There's also Super Production in the SCCA, not sure on the rules, but it's a very open class for production based cars.

According to the web pages that I have looked at, "Super Production" is the home for things that don't fit into the GT or Production classes (which this Honda-powered FC would seem to fit). Realize however, that this is a class where you would be running against fully race prepped Porsche turbos and ex-CanAm cars. ITE would be a much safer place to run, and much less expensive.

-bill

That's what SPU is good for, it's for the smaller displacement cars. A freind of my dad's runs a BMW 2002 in SPU and he regularly gets on the podium. It's a fairly trick car, but it's still an amateur car, it's no factory job. There's still lots more speed to be made with that car, as the suspension isn't fully tuned yet (he concentrates on the motor mostly, or at least he used to, untill with some minor tweaks at my urging got him a new personal best lap time at SRP). He's won the SPU class several times even. You can go up to 2L in SPU IIRC, so unless it's a very new S2000 motor, then it's SPU, and not SPO (open = turbo porsche, etc).

http://www.zeebuck.com/02bc/memgallery.html

Jeff Roberts, top car if you're interested.

hmm... that SPU could be interesting. Do they allow engine swaps in that class? If they do, I should probably build the car to those specs. Can I get a link to the rules?

Here's the SCCA Club Racing rulebook link (it's a big file): http://www.scca.com/_FileLibrary/File/GCR2006.pdf

The brief Super Production description (1 paragraph) is on page 92.

You should contact the local SCCA chapter to get a more thorough set of rules, as classes such as SPU and ITE are set by the individual regions, so the rules are different everywhere.

Umm, do you have a section number? The only place that I saw a reference to Super Production was on page 81 in the main section (GCR-81), but I didn't see any mention of the class in the production section.

Page 92 (in *my* pdf copy of the 2006 GCR) talks about oil catch cans and master switches (17.26-29).

Thanks,

-bill

There used to be a discussion board for SP, but I can't seem to find it now.

IIRC, the cage needs to meet GT build specs.

Sorry, page 82 of the book, page 92 of the PDF. Section 17, Automobiles. The regional chapter will have more information.

It's basically a class for Production and GT cars that don't fit into any Production or GT class.

That's a neat project! Funny how many people seem to get offended by the project (refering to the linked thread).

Anyhow, I don't have any rule books for SCCA/NASA ect, but looking at your project I noticed that a good chunk of the firewall/bulkhead was cut to move that engine in. I wonder if this could be a tech issue with the sanctioning bodies.

Don't know for sure, but it might be something to look into in advance, or perhaps someone else can chime in here, I could be offbase.