Door bars

[JMortensen]

I'm reading up on door bars, hoping that my bender and tubing will both come in with enough time for me to get the rest of the cage installed before I move. I copied katman's cage design pretty closely with main hoop placement, so the hoop is quite a ways behind the door post. This makes for a really funky door bar that has to go straight until it clears the door post, then out into the door area, then back in at the front. Seeing as how I don't have really any experience bending tubing and such, I think this is going to be a real PITA.

 

So I had an idea, and I'm hoping you guys will give it a yea or nea.

 

Here is where the main hoop is in relation to the door:

 

And here's what I'm thinking about cutting out of the door area:

 

If I cut this area out, then I could have a very simple shape to the door bar, like a bracket when viewed from above: ]

 

Then once the door bars were bent I could use a piece of .060" thick sheet to attach the door bar to the chassis, and my theory is that this would be a damn good way to attach the cage to that part of the chassis too.

 

Only downside I've been able to come up with so far is the passenger side of the car. I'm not even going to have a passenger seat, at least for a while, so I was thinking of not doing anything over there, or doing a simple X with my lightweight 1.625 x .065 tube just for the sake of stiffening up the chassis, but it won't match so that side of the car won't be as firmly tied in. I think that's probably not too much of an issue on the whole, but I'll let you guys tell me I'm wrong if that's the case.

 

Also with the configuration of the door bars I think I'm going NASCAR style just because that seems to be what is currently acceptable to SCCA. I want to get the door bars low to make it easier to get in and out. I was wondering if there was a particular guideline for how far apart they should be or anything like that.

 

I'm also a bit concerned about how to weld the door bars to the main hoop. Right now I'm leaning towards cutting more holes in the fenderwell and welding the cage, then patching the holes, much like I did when installing the X from the strut tops to the rockers: http://forums.hybridz.org/showthread.php?t=119861

[johnc]

This makes for a really funky door bar that has to go straight until it clears the door post, then out into the door area, then back in at the front. Seeing as how I don't have really any experience bending tubing and such, I think this is going to be a real PITA.

 

So what? You'll learn something and be able to point to it and say, "Look what I did!" The door jamb is a pretty strong part of the car and I, personally, wouldn't want to cut it up just to make things little easier during fabrication.

 

The double door bars can start high (mid rib cage for the top bar) at the main hoop and then taper forward and down. At a minimum I would keep them at least 6" apart at the narrowest point (in the front) and about 4" above the rocker.

 

SCCA considers an "X" door bar to be one bar. For the passenger side I would run a double door bar also but just keep it straight. Build that one first to get some practice with the bender before tackling the more complex driver's door.

[JMortensen]

So what? You'll learn something and be able to point to it and say, "Look what I did!" The door jamb is a pretty strong part of the car and I, personally, wouldn't want to cut it up just to make things little easier during fabrication.

You don't think it would be even stronger with the bars running through and .060 plates attaching it on both sides of the corner?

[JMortensen]

Hehe, Speedway just called, my bender is on the way finally!

[johnc]

I don't know.

[katman]

I came up with that hoop placement before SCCA allowed us to have NASCAR style door bars protruding into the door cavity. I still believe that to be the best place for the main hoop, and your interpretation looks perfect. After you get it gusseted in at the bottom it will be perfecto.

 

After SCCA allowed us protruding door bars I built a second car with the main hoop in...drum roll...EXACTLY the same place, because I still believe it to be best/strongest like you have it. Our trashcar style door bars had an "S" bend in them to clear the door sill. PM me and I'll send you some pictures.

 

I would think that if you fit the door bars into the post and welded the post sheet metal to the bars you'd be just as strong for all intents and purposes, but its a lot of work. Our rules didn't allow us to do that.