Hey guys, just a quick note to find out if I'm thinking along the right lines or not...

I've already bought (but not yet installed) a set of weld-in SFCs for my car. This will be a "weekend toy" street car about 97% of the time, but as mentioned in other posts, I will also be taking part in some high-speed contests as well - and one of the contests that I have my eye on requires a 6-pt or better cage. (If I do decide to get the cage, I'll probably sell the SFCs.)

I'm thinking that if I decide to go with the cage, then there's no point to installing the SFCs, as the cage will provide plenty of structural reinforcement - would you say that that's a fair assessment?

As far as I can tell, there are two arguments in favor of SFCs over the cage - first, you not only have less weight with the SFCs (a big factor for me), but you're also adding that weight in the best possible place for handling purposes (if you have to add weight, that is).

Second, if the cage is installed as it's supposed to be, then the main bar going across the roof will be immediately behind the heads of the driver's & front passenger's heads - and if you get rear-ended, the whiplash could result in a cracked skull or two... (I'm not planning on having the "halo bar" that goes around the side windows & windshield.)

Is my understanding basically correct, or is there something I'm missing?

Thanks guys.

 

A "cage" completely surrounds the driver by including a halo and a-pillar bars. What you're describing is just a roll bar which can be a 6 or 8 point.

Install the SFC and leave them in. Even getting a roll bar or a roll cage, you'll still need the SFC. A unibody car needs both because a roll bar/cage does not tie the front and rear subframes together.

A typical 6 point roll bar will add about 70 pounds to the car. Although you don't need it until you get into the 11 second range, even a 13 second street car can benefit from a roll bar just in how much it stiffens up the chassis. For a street car, install swing out door bars to make getting in and out easier. You might as well pull the rear seat since once a roll bar is in place, the rear seat access is greatly restricted.

Your main hoop needs to be within 6" of the driver's head/helmet. Any tube that is close to the driver's head must also have the proper padding on it so even if you do hit your head while in an accident on the street, the padding will keep the injuries down.

 

If your going to install the weld in connectors, which is a good thing to do, I'd also take the time and install a 6 rollbar using pro street rear runners. These rear bars run along the roof line and give you more room in the rear seat. You may also look into swing out bars? If you need to use your rear seat, I've seen places install a swing out bar that goes between the main hoop, this way you have easy access to the rear seat.
If I can suggest a place, I'm a big fan of S&W Racecars. They have eveything you'll need. My 69 Camaro is made up of all their components (12 point cage, narrowed rear frame, narrowed 9 inch, ladders, coil overs, wheel tubs, everything..) They make good stuff at a good price.
www.swracecars.com
Adding a rollbar may add weight, but with the SFC's it will add strength to the frame.
Also make sure you use a good mig or tig welder. You don't want the welds to break out on you.

Good luck
Bruce

 

You need both.

I have a 6-point bar, and saved weight using chrome moly. I also had custom SFC's built from chrome-moly by the same shop, and installed at the same time, maximizing the roll bar connection through the floor to the subframes.

Relying on the sidebar of a 6-point would not be anything like using an SFC. With a full cage, it could be argued that the mandatory rocker panel bar will replicate the SFC, but that would still require that the hoop and the front brace mount points of the cage attach to the subframes.

 

OK, thanks guys - that's why I ask, to find out where the gaps in my knowledge are... I've pretty much decided to lose the rear seat anyway, but the pro street rear runners are an intriguing idea.

I've also wanted to go with chromemoly, but I need to find out roughly how much more it'll be over the regular "mild steel" stuff.

Again, thanks for the replies!

 

You can figure about double the price.

 

Plus a TIG welder or know someone who will TIG weld it for you. At least a mild steel cage can easily be MIG welded in.

The weight saving isn't that much compared to the increased cost.