Most door bars I have seen are bowed outwards a little bit, some are straight (perpendicular to the central hoop). Is there a reason one is prefered over the other, only reason I could think of is a straight one would limit leg room while a bowed one gives a bit of freedom to the knees.

 

The issues are safety, egress and chassis stiffness. The basic X-bar running parallel to the pillar bars will be stiffest (generally). But it provides very little crush space and poor room for driver egress. Opinions differ about the best/safest NASCAR door bar set up, but those are the issues. I'd rather sacrifice some chassis stiffness for safety and comfort. That's not to say the X-bar isn't safe, its just a matter of degree.

EDIT: there are some nice examples here: http://e30m3performance.com/te...m.htm


Modified by thawley at 8:52 AM 9/8/2005

 

It has been pointed out before that the strait door bars give more room for the car's outer body to crush and absorb energy before the bar would impact anything.

 

Somebody post pictures of Mike Quan's door bars.

You can have the best of both worlds like Chris's car in this thread; https://honda-tech.com/zerothread?id=1356302

Keep in mind that factory Porsche Cup cars also use that method.

 

The crush zone makes sense, do they make NASCAR style bars that run straight across. (Not X bars but just straight across.)

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mos &raquo;</TD></TR><TR><TD CLASS="quote">It has been pointed out before that the strait door bars give more room for the car's outer body to crush and absorb energy before the bar would impact anything. </TD></TR></TABLE>

while thats all fine and dandy i have seen several impacts of late, were an X bar deflected too much and if the impact were to be on the drivers side the driver would have been impacted.


You need to keep in mind that when looking at those cages thawely posted that they are FIA cages, and IMO an FIA cage like the ones shown can't be looked at peace by peace they must be looked at as a whole.

When i was having my cage built, i knew i wanted door bars that went into the door shell. I didn't like the NASCAR door bars as i thought they were too much for the protection they provide, as did my cage builder. so we opted for this X bar design that i think will protect extremly well, and still absorbe some energy.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mos &raquo;</TD></TR><TR><TD CLASS="quote">It has been pointed out before that the strait door bars give more room for the car's outer body to crush and absorb energy before the bar would impact anything. </TD></TR></TABLE>

Only true for FIA cars or if you have stock doors (non gutted) with door bars.

FIA cars has crush structures (foam like) on the doors to absorb some of the impact.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by johng &raquo;</TD></TR><TR><TD CLASS="quote">Somebody post pictures of Mike Quan's door bars.

You can have the best of both worlds like Chris's car in this thread; https://honda-tech.com/zerothread?id=1356302

Keep in mind that factory Porsche Cup cars also use that method.
</TD></TR></TABLE>

What happens if your left arm gets caught between the 2 sets of door bars?

This is how I did my old GT4 Civic

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SMSP &raquo;</TD></TR><TR><TD CLASS="quote">What happens if your left arm gets caught between the 2 sets of door bars?</TD></TR></TABLE>

What if you're upside down, on fire, pinned between a tire wall and another car? There's a lot of "what if's" Dave.

Edit... my door bars are very similar to yours.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by johng &raquo;</TD></TR><TR><TD CLASS="quote">

What if you're upside down, on fire, pinned between a tire wall and another car? There's a lot of "what if's" Dave.
</TD></TR></TABLE>

Then you are screwed, but not because of the design of the cage.

 

Here's another example. I had a X bars tied into a straight bar that runs from the main hoop to the front of the car. Just trying to add protection and rigidity.

http://groups.msn.com/thegonza...D=448

 

This was when the car was still in SSC trim but we still have full door interior panels and guts, adhering to the crushable structure theory. The cage in the new shell will be essentially the same, but with the front leg a little farther forward and different treatment of the IT-legal 7th and 8th pick-up points.

K

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by johng &raquo;</TD></TR><TR><TD CLASS="quote">You can have the best of both worlds like Chris's car in this thread; https://honda-tech.com/zerothread?id=1356302
</TD></TR></TABLE>

I really think that's very dangerous. If you do slide into something hard enough to flatten the extruding door bars, you are very likely going to have enough momentum in your extremeties that they will fly in the direction of those collapsing door bars - like SMSP suggests, your left arm gets caught between the 2 sets of door bars and you are very much in a world of hurt.

Look at these (big pic, don't want to mess up everyone's reading) bars and realize that they were not an S-bend to begin with but looked like the door bars pictured in the other thread (and my left arm from tricep to wrist demonstrated that I hit either them or the window net hardware pretty damned hard so the idea that your arm could get trapped in there is very easy for me to visualize). http://www.ipsolve.com/racestuff/v1/DSCF0142.JPG

 

Phat-S,
I believe the pictures in this link is your car with the cage by Walt Puckett: http://www.deltagroupmotorsports.com/work/

I really like how far the door bars extend away from the driver and how high up it goes. I have seen the same design up-close in Bryan Shugg's Cobra and to me seems safer than some of the other designs posted here. I am no expert but if I were having a cage built, the cage in the link above would be the one I would choose.

 

leadfoot321, indeed they are (v2 p1 in my signature). The one picture that's not in that set is this one (http://www.ipsolve.com/racestuff/v2/...s/DSC_0318.jpg), which is the down tube coming from the A-pillar to the door bars. I honesly think its one of the best looking cages top to bottom I have ever seen and its not just because it's my car - Walt's cage really is top shelf IMO.

And I am with you, I really like how deep set you are in the seat behind his door bar structure. I know a lot of folks like the straight x bar in the door way but for my concern, I really really like how far away from the body this is. Ironically and I didn't realize this until I was getting out of someone else's car, the fact the opening kicks out so far, even though they are up to (and over) my seat's shoulder, its really quite easy to get in and out of (I have even noticed this on people a lot taller than me).

 

Adam,
I think we all understand in a crash, anything can happen, and we're all looking for ways to minimize injury, but I don't think I'd go so far as calling that example a poor design, although it could be built stronger and closer together.

As I said earlier, factory Porsche Cup cars are built similar. For example, I took these pictures a few years ago at Fordahl Motorsports who at the time I believe was prepping ALMS cars, and is still maintaining. If it's good enough for Randy Pobst.....

The nuts & bolts of this is, there's a lot of options when it comes to door bars.



Higb res images of door bars below.
http://jellybeanracing.com/John/DSC00010.JPG
http://jellybeanracing.com/John/DSC00013.JPG
http://jellybeanracing.com/John/DSC00015.JPG

Another idea..
http://jellybeanracing.com/John/DSC00008.JPG

 

John, I won't get into a spitting match over safety items because there's just too much karma out there, both good and bad, to temp fate. A) due to my personal experience in an impact, I have seen bars such as those shown deflect inward over a significant distance. B) I can visualize a danger of one arm caught between the x-bar structure and said door bars. C) The GA Rolex Porchey that I am familiar with locally does not have a straight X in the doorway but one that is pre-bent outward (I cannot tell if the pictures you are showing is the same but if so, they are a lot closer to each-other than what is in the white car). D) I do not think you can redily take a design from an ALMS car and plug it into a street car and think that you have effected the same results (I think if you took the door bars from the Lambo last year and put it in a Civic, you could probably drive the Lambo through the opening).

I think we both agree, WRT door bars, you can ask 5 people and get 7 answers as to how they should be built. I was going to say that I never said those bars were a poor design but in all fairness, that I find that setup dangerous would suggest I do feel so. There are a lot of designs I don't necessarily like due to my own prejudice but this one that we are looking at has a much different effect on me than dislike.

I believe there are definately things one can say are possible yet SO improbable that they should not find their way into a practical discussion on safety. I feel however, based on experience with both arm movement and the movement of such door bars inward, that my concern is valid and therefore makes that, as shown, dangerous. At the end of the day, you might call my concern one of those possible yet impractical, I personally would not.

Let me rephrase my comment in this way. I think, without attention to several details to prevent an arm from becoming entrapped in that well between the sets of bars, its a dangerous design. I'll go back to my corner now (behind my door bars ).

 

Is that a CF door i see? If so then you better have 2 sets of bars.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by phat-S &raquo;</TD></TR><TR><TD CLASS="quote"> I'll go back to my corner now (behind my door bars ). </TD></TR></TABLE>

Me too

I understand your viewpoint.

I'm just trying to contribute ideas to the original poster.