I just picked up my competition engineering 8pt cage from summit this weekend. Ive been seeing alot of people on here that say that they tied their cage, or welded, to their sub frame connectors. How exactly do you do that, just by welding in the plates for the cage right over where the subframe connectors are or what? I was just wondering if I could go ahead and get my cage put in and painted, then go back later and put the SFCs on later.

 

Nope! SFC first then weld cage onto sfc's. Doesn't work in reverse. do a search and it should answer all your questions.

 

can you explain that a little more?

 

from what I've seen and read, you have to weld in your subframe connectors first if you paln on putting in a roll cage. You will install your subframe connectors then when you actually weld the main hoop and if possible the down bars and door bars to the sfc's. I'll try to find a link that shows it or talks more about it.

 

There's no need for it from the rule book. If you install 6" x 6" plates that's fine. Actually theres a rule saying if you don't mod the floorpans more than 1 sq foot or so an 8 pt is up to specs for a second longer. Also my bars (S&W) weren't anywhere close to being in the area of my boxed Spohn SFCs.

 

I thought there was a rule saying that the main hoop has to be X" away from the back of the drivers head?

 

here you go. i cut small holes through the floor, then cut small holes in the 6x6" plates then slid the 1 1/4" bar through it after forming it to the floor, then welded the bar to the sfc and the halo. these are there for support when the swing out bars are removed for road driving. when the plates are welded down it looks as if the floor has not been modified, most people don't even think they go through the floor.

 

I'm not saying you have to weld the cage to the sfc's. I'm saying it's the best way to go for full structural integrity. The cage being welded to the sfc's is much stronger and safer. Yes the rules do give measurements for helmet to halo distance and where the door bars must cross your arm and blah blah blah. You can get the rules online or just get the actual book. The best way to go would be to get an NHRA and an IHRA rule books. Then look at the rules for both. Go with the strictest rules from each book and you can't go wrong.

Anyway... the original point was why sfc's before the cage. It was explained this way to me. Think of your car as soft and flexible. You have two rigid locations, the front and rear subframes. By putting in sfc's you have connected the subframes. This means the soft center section has been given a rigid structure to keep it from flexing. If you take the car out and apply some serious power without sfc's you can twist the body. A roll cage adds little in protection from body flex and twist. If you put in a roll cage you could be stuck with a body that sags after you weld it in or will flex taking it down the track.

 

you may or may not have noticed but it is impossible to meet the nhra rule for helmet to halo distance if you are over 5.9'. almost every track inspector will overlook this particular rule on these cars if the rest of the cage is done right.

also, installing a roll cage or roll bar as long as it is 6 points or more and has been triangulated will prevent body twisting after it is installed. anything that was there before hand must be repaired before the installation or you will be stuck with a twisted ride. sfc's are not required to eliminate body flex and twist IF the roll cage is done right. mine started out as an 8 point roll bar, but i added the rear cross brace, door bar braces that mount to the shock mounts, the secondary floor bar and the main hoop cross sectional braces, and all the floor point have 6x6" 1/8th " thick steel plates welded in. i only put the perimeter sfc's on because i had them laying around and wanted easily accessible jack points for my lowered car.