Door Opening "X" Bars as Side Protection

[Knestis]

Wow. Don't blink.

K

[Greg Amy]

In all fairness to the Mee-Otter, I don't know that I would have done any better...yes, that hurt to write, but I'll be OK...

[Racer Chris]

It looked like he had time to slow way down, so the impact was less than 50mph even.
Too bad he tried to follow the first car through instead of heading for where the spinning car had been.
IMO this certainly proves the gross inadequacy of the simple X door bar design!

[RexRacer19]

IMO this certainly proves the gross inadequacy of the single X door bar design! When built in a single plane without any gussets added.

I had to add to that statement. As Greg stated earlier, the tubes will be put in tension if the X is formed in a single plane. They can be designed and built better. For the passenger side of the car, I honestly don't think it needs to be bomb proof. There is a lot of room between that door and the driver. If you have to add ballast to make weight...it is a good place to put it though...

After looking at that video, one has to ask. If that hit were on the driver's side, and let's say the side impact protection was two complete "parallel" bars with maybe three vertical stringers tying them together, would the driver have come out unhurt?

[Racerlinn]

Racin deal. Zigged when he should have zagged.

[tnord]

comments please. this would be fore a miata, with main hoop mounted on the package shelf, and the proportions aren't exactly right in my little drawing. i don't think the distance from the rearward stringer to the main hoop would be that far.

bold lines indicate attachment/welding points.

[Greg Amy]

...a miata, with main hoop mounted on the package shelf

A good idea, leaving plenty of space for a 6-foot + driver:

http://www.kakashiracing.com/images/DSCN3703.JPG
http://www.kakashiracing.com/images/DSCN3702.JPG

http://www.kakashiracing.com/forsale/sm.html

[tnord]

or 6'3'' driver.

any reason you chose to go in front of the dash with the a-pillar bar?

[timrogers]

What happened to the video?

Works fine for me.

[Greg Amy]

any reason you chose to go in front of the dash with the a-pillar bar?

Simply just for ease of build and better leg side-hit protection. Descending side bars were for ease of ingress/egress.

[Wreckerboy]

or 6'3'' driver.

any reason you chose to go in front of the dash with the a-pillar bar?

Travis - the cage Chris put in my car attaches at the front of the car in a fashion very similar to what you describe. As you probably know, dash removal is not that difficult. (Though I freely admit I paid Chris to do that for me as well.) The advantages are increased access area - the downtubes on mine are right in line with the dead pedal on the driver's side. The only downside is that the fuse box approaches "genuinely insane" in terms of access, but it is worth it in my eyes.

Remember, not too long ago there was a debate about the forward attachment points (at least in the northeast) and whether it was legal to attach them to the brace that runs behind the dash. Ultimately this was ruled illegal - search over at the Daniels website on the subject and I think DDG may have been involved. (I know you can't post and ask over there! )

[seckerich]

comments please. this would be fore a miata, with main hoop mounted on the package shelf, and the proportions aren't exactly right in my little drawing. i don't think the distance from the rearward stringer to the main hoop would be that far.

bold lines indicate attachment/welding points.

A cage like yours is what started a huge debate on other sites about door bars. Cars were sent home because the door bar did not connect the main hoop and down tube. My read is that a tube that goes to the attachment point for required element is same as going to that tube. The lower tube in the door counts as a seperate attachment point unless you stretch the plate for the main hoop down the allowed 15 inches. Not something you should get grief over but it is not "technically" legal. I had a car come through with your style cage and we added a short piece of tube from the lower bar to the hoop. Rules do not say "continuous" door bar.

[DoubleXL240Z]

Travis,
I believe as well that your design would not be legal, nor would I think that would be a safer alternative. I believe the way to the strongest intrusion protection would be to have your door bars attached to the main hoop and a-pillar. As it sits now the door bar is attached to sheet metal at the rear. Think monocoque here!! I also would not do a main hoop on that parcel shelf. Drivers side impact at rear wheel and there is nothing preventing a left rear tire from being punched into your kidney etc. or the whole car coming through. Again, try to think monocoque. The high main hoop route starts protection 2 1/2 feet off the ground and your sitting under it. Where most bumpers are flying around. Honestly if you don't fit with a safe cage try a different car. I'm 6'4" so I'm in familiar situations.

[tnord]

Travis - the cage Chris put in my car attaches at the front of the car in a fashion very similar to what you describe. As you probably know, dash removal is not that difficult. (Though I freely admit I paid Chris to do that for me as well.) The advantages are increased access area - the downtubes on mine are right in line with the dead pedal on the driver's side. The only downside is that the fuse box approaches "genuinely insane" in terms of access, but it is worth it in my eyes.

meh. i never had to get at it once in the 5 years i had my last car. i'm not too concerned about that.

Remember, not too long ago there was a debate about the forward attachment points (at least in the northeast) and whether it was legal to attach them to the brace that runs behind the dash. Ultimately this was ruled illegal - search over at the Daniels website on the subject and I think DDG may have been involved. (I know you can't post and ask over there! )

you mean that stock tube that runs behind the dash? i wasn't planning on attaching to it, but replace it. not sure if IT and SM rules differ here, but i thought that was legal. no, i don't remember the debate, and i can't search on that site either. not that that site has much of anything useful going on anymore anyway.....

[tnord]

A cage like yours is what started a huge debate on other sites about door bars. Cars were sent home because the door bar did not connect the main hoop and down tube. My read is that a tube that goes to the attachment point for required element is same as going to that tube. The lower tube in the door counts as a seperate attachment point unless you stretch the plate for the main hoop down the allowed 15 inches. Not something you should get grief over but it is not "technically" legal. I had a car come through with your style cage and we added a short piece of tube from the lower bar to the hoop. Rules do not say "continuous" door bar.

that's a good idea steve. with the 'X' bar design i feel like it leaves a rather large "gap" down at the bottom of the door by the rocker. that straight piece of bar with the separate attachment point was just my attempt at solving that.

i'm thinking your statement about "a tube that goes to the attachment point for a required element is same as going to that tube" is in reference to the bottom of the two 'X' bars, or the middle of the three? others have interpreted the rules in the same way, as the NASCAR bars in my last car had the upper tube attached to the main hoop itself, and the lower bar was attached to the plate that the main hoop was attached to.

were either one of these drawings how you "solved" that problem?

[spnkzss]

that's a good idea steve. with the 'X' bar design i feel like it leaves a rather large "gap" down at the bottom of the door by the rocker. that straight piece of bar with the separate attachment point was just my attempt at solving that.

i'm thinking your statement about "a tube that goes to the attachment point for a required element is same as going to that tube" is in reference to the bottom of the two 'X' bars, or the middle of the three? others have interpreted the rules in the same way, as the NASCAR bars in my last car had the upper tube attached to the main hoop itself, and the lower bar was attached to the plate that the main hoop was attached to.

were either one of these drawings how you "solved" that problem?

Just FYI. If it's strictly IT, I don't know about SM, IT allows 144 sq in now with no side longer than 15". And yes the second picture that is another attachment point, unless you can take advantage of the previously mentioned rule.

[tnord]

Travis,
I believe as well that your design would not be legal, nor would I think that would be a safer alternative. I believe the way to the strongest intrusion protection would be to have your door bars attached to the main hoop and a-pillar. As it sits now the door bar is attached to sheet metal at the rear. Think monocoque here!! I also would not do a main hoop on that parcel shelf. Drivers side impact at rear wheel and there is nothing preventing a left rear tire from being punched into your kidney etc. or the whole car coming through. Again, try to think monocoque. The high main hoop route starts protection 2 1/2 feet off the ground and your sitting under it. Where most bumpers are flying around. Honestly if you don't fit with a safe cage try a different car. I'm 6'4" so I'm in familiar situations.

i'm no engineer, so i don't know how well i could argue that attachment at the package shelf is equally as safe as at the "rocker." all i know is that it's where my last cage was attached, where Greg's was attached, and where countless other miata cages are attached. i can't see how it's any worse than the flat plates that mount strictly to the floor pan up front (also legal).

i also know that my car suffered about the largest rearward impact you can have in a miata, with the cage attached at the parcel shelf, and faired pretty well. i think the tire was knocked into the back of the seat, but changing the location of the main hoop wouldn't have prevented it.

[tnord]

Just FYI. If it's strictly IT, I don't know about SM, IT allows 144 sq in now with no side longer than 15". And yes the second picture that is another attachment point, unless you can take advantage of the previously mentioned rule.

thanks Rob. so something more like this?

PS - this has been a very helpful discussion for me at least. Thanks everyone.

[Speed Raycer]

Travis... with the 144" & 15" long rule, you can get all the way down to the corner brace from the package shelf with sq.in. to spare. There's a mass of structure in that whole area.

Also, ideally you want the A pillar brace to head to the node down at the front pad... sometimes you have to depart from the ideal to make things work, but you have some room there... basically you're duplicating the down bar in tGA's Miata cage.

I don't think that eliminating the dash tube is legal at all but that's a different thread

[tnord]

you're right scott.....i guess i'd be just adding a dash bar rather than replacing one.