empire_619

im pretty new at this roll cage sutff.Im going to start building my roll cage but i wanted to see does any body have the guidelines that i need or specifications for this cage?

9sec93

iTrader: (67)

order the book
http://www.sfifoundation.com/drag.html

NINET3Z

Order the book for sure. But I would also talk to your division tech guy or a local chassis builder who is familiar w/ F-Bodies. (I'm assuming an F-Body) There is a lot of gray area when it comes to actual application of 25.5 rules to a stock floor pan F-Body. Good luck with your cage. Post pics when you get started.

Fireball

iTrader: (21)

definately...those specs were definately written for a car with inboard subframes *cough*mustang*cough*

Need alot of interpretation to apply to F-bodies...

NINET3Z

Yeah, we quit trying to get answers from SFI and NHRA. My chassis guy kept the 2x2 weld in sfc, and put the inside and outside bars in. Now the question is, do the stock rear subframes count or should we just build new inside the car as part of the cage?

Fireball

iTrader: (21)

what do you mean by the rear subframes counting? spec says you have to have bar 1 connected to the rear subframe via a middle bar (2B)

NINET3Z

I don't have the book here, but part of the book gives specifics about size etc. of the frame behind the crossmember, another place it calls those bars "sub frame connectors". I see alot of guys only doing 2 down tubes from the main hoop to the back of car. Some other cars basically have replaced the stock rear subframe with tubes inside the car (like Burkhart and Stenod do).

Fireball

iTrader: (21)

yes...the book calls 2A and 2B "subframe connectors"

what we did on mine was run a 1 5/8" bar between the two downbars (which were welded to the subframe) and then ran (2) 1 5/8" bars between bar 1 and that crossbar (see pic). Inspector was happy with it.

NINET3Z

That is what I mean. Some cars don't have that but they pass. I guess it depends on who's inspecting.

Fireball

iTrader: (21)

We added those bars per my discussions with Madman on his interpretation of the spec...

besides...it stiffens up the rear suspension to have it triangulated like that

RAGENZ28

iTrader: (5)

If you're building a car that fast I would add those bars also, ditto on the reasons fireball said.

TTPMatt

iTrader: (18)

The guidelines leave a few things on the table as per they are a generalization of guidelines for all cars. It really depends on the inspector. When George completed the 25.5 on his c6z06 there was a lot of play to the rules considering the aluminum frame, but the cage was certified here.
We are building our 25.5 for our race car now. We're going to complete this one a bit different than normal customer's cages and keep a lot of the tubing inside the car with troughing the floor. I am going to do something like Fireball with the rear triangulation, figured we can try a few different things on our test bed.
Beautiful cage Fireball, hope to see you at some of the Cecil Sat Night events...

MADMAN

iTrader: (4)

The SFI specs and the NHRA allowing the inspectors to interpret them is bullshit!!!! BUT they are the only game in town and we as chassis builders have to follow the rules to be able to play.

I have the hardest inspector around and have seen him fail cars that other inspectors have passed. The best thing to do is get a copy of the SFI spec and READ the guide lines not just look at the pretty pictures. Build the car to the spec and put ALL the bars in whether you think they dont have to be there or not.

Old Geezer

iTrader: (3)

"The SFI specs and the NHRA allowing the inspectors to interpret them is bullshit!!!!"
Yep. Best to try to get the inspection done B4 he goes to his regular job at Mickey D's...