Jon V

Just wondering what you guys thought of this bar added between the door bars and the Pillar... It was added mainly for ease of getting in and out of the car, although it should add a little rigitity to the cage...



Is this going to cause any issues with tech inspection for NASA or SCCA events? It's and S2000 if you couldn't tell. The rest of the cage is done to spec just added this piece...

Input?

prkiller

Was there suppose to be a pic? Don't see one.

rotten

TTIWWOP

Jon V

For some reason I can't edit my first post? So here it is again



Not sure what happened to the pic I posted yesterday right after all the updates...

PRkiller- This is charlestons buddy with the Black EK hatch. met you at Willow a few years back. Been building the K car ever since, should be back out in the next couple months ready to hurt some feelings at the time attacks...

Jon V

looks like the pic is back in the first post again now?

rockdude14

i cant see anything
and when i go to the site hosting the pics i get an image thats 1pixel by 1 pixel
my guess is they are trying to stop hot linking to other sites

might want to try imageshack or photobucket
but maybe other people can see them

Kamin

i cant see ****

Jon V

how is that? rehosted the pic in the first post on photobucket...

Hopefully that helps. I have been able to see it the whole time so I'm not really sure whats wrong? sorry

gotocrx

You have made a supplementary A-pillar. It is a pretty standard cage element. Some things to think about:

-proximity to the wheel and your hands, can you touch it while strapped in?
-are the door bars supported beneath where it attaches?

lookey in the window of this one:

prkiller

Pic is back now.

That should pose no problem with Tech!

2point0VTEC

is this the guy that you were telling me about jon? The cage looks good. It don't look like it will be a problem...

prkiller

Whats up with the seat though? Why not go with a proper racing seat for the type of car being built?

Johnny Mac

The modified A-pillar doesn't really stiffen the cage in terms of overall torsional stiffness between front and rear suspension. However, its main benefit is to stiffen the long A-pillar to main hoop bar by shortening its span somewhat. This is most important in a rollover where this long span could collapse if a large enough impact load should occur.

To torsionally stiffen a roll-cage, you need to triangulate the cage more. It is nearly impossible to fully triangulate a cage since diagonal bars would be in very close proximity to the driver causing safety concerns or the bars would not allow easy ingress or egress of the driver. In addition, NASCAR door bars reduce torsional stiffness compared with in-plane door bars. Triangulation helps stiffen the cage by reducing deflection caused by large bending moments in the cage members and instead creating a cage where the tube members are either in tension or compression, which is much stiffer than in bending.

Personally, I would rather have a safe cage with NASCAR door bars and just triangulate my cage where it is convenient to do so. I am not going to place a bar close to the driver so that in the event of an incident, the driver's body might be compromised. Besides, most sedan or couple based production cars are relatively torsionally stiff where we don't see a lot of handling issues relating to an overly flexible chassis when used in competition. Convertibles are another story however.

A roll cage should be built with safety as a primary focus and torsional stiffness as a secondary focus. Here are a few things to look for in a cage.

1. A well built cage will have the centerlines of each member acting at (or close to) a common point in space where these all of these tubes meet at a joint. If this is not done, the tubes that do not meet at a point cause a joint eccentricity, which will cause a bending moment in one or more of the tubes. If this eccentricity distance is small, then the resultant bending moment will be small and for most cases, which is fine. However, if this distance exceeds an inch or more, then the BM may not be so small and this joint may be a good candidate for a gusset. Structurally, a gusset serves to increase the local bending stiffness so that both stresses and deflections are minimized at the joint.

2. If the rules allow, make the cage an eight point cage instead of the customary six point cage. The extra two points attach the shock/strut towers to the main cage so that in the event of a frontal collision, there is extra stiffness in the cage to deal with it. This also helps stiffen the torsional stiffness of the cage if a strut bar and a tie from the strut tower to the firewall is done. In racing, since a Hans or other SFI device is required, the extra load felt by the head in the event of a sever frontal collision will not cause an undue risk of basal skull injuries as seen in the past for this type of collision.

3. Make sure the drivers head doesn't contact the left side halo bar in the case of a side impact. Tall drivers may need to lower or recline their sitting position or both to give themselves ample head clearance. In extreme cases, the floor of the car should be lowered. This is very important as even a brush with a wall might cause a concussion or worse if the head is allowed to make contact with the cage - even with the cage padding.

4. DOM steel is better for a cage than Chromoly because steel (1018 or similar) will deform plastically much more before failing than will Chromoly - even normalized Chromoly. Remember, they both have the same Young's modulus and thus the same stiffness for the same size tubing. However, Chromoly realy needs to be heat treated after welding to reduce the problems associated with heat-affected zones (HAZ). Mig welding is fine as is the more labor intensive and expensive Tig welding.

5. Use the biggest plate area with the appropriate thickness as allowed in the rules for anchoring the cage to the chassis. Boxes that attach to the sill and frame rails are even better since they transfer load from the cage to the chassis in the stiffest location. Do not rely on the thin sheet metal use for the floors for very high loads since it will tear out very easily.

6. Tie in the main hoop at the highest door bar to the chassis so that in the event of a side impact, the main hoop doesn't fail in bending.


There are plenty of other things to do for a good cage and we'll leave those for later discussion.

sackdz

Lols Johnny, don't forget to breathe!

I can't see the picture.. is it working now? Maybe its my firewall.

I see the Japanascar pictured below. I am wondering if the drivers hand or wrist could impact that thing in a rollover or side impact. Doesn't seem like arm restraints would matter for that location. That would be my only concern, but there are worse things than a broken arm I guess.

I am trying to imagine myself in a rollover with that extra vertical member.. I think I would grab onto it =D

Jon V

You may be able to touch it while strapped in but just barely with your arm fully extended. We didn't want to attach it to the lower bar running beneith the nascar bars for fear of a side impact pushing that lower bar in to the drivers seat.

The guy I am working with is in to Nascar stuff and also has a "Modified" circle track car. he uses those seats in the circle cars and loves them? they are relitevely cheap and are very supportive and not as uncomfortable as you would think... he has always been in to racing and is now starting to dabble in teh Honda stuff. he is building an H4 DA integra and is doing teh cages to help pay for his car parts and get some publicity in the scene. We are doing the cages out of his transmission shop in Palmdale Ca. if anyone is intersted he's offering really good pricing for spec cages just to get some done and get some publicity.


J-Mac

We originally wanted to go through the firewall and tie in the front strut towers but the owner doesn't want to pay for it... So no go LoL

As I said the A pillar bar pictured was added mainly to ease getting in and out of the vehicle, we did a pretty good job of tucking the bar up behind the hard top so there isn't really much to grab on to while getting in and out of the car...


Sam yup this is the guy...


Thanks for the input


I'll try and snap a few more pics of the rest of the cage and the fuel cell and cover. The car came out really nice, I think. Just needs to be gone over and final welded after the owner jumps in one more time to check fitment and clearances...

prkiller

I believe it's still not going to be as safe in a Honda as a Sparco or Racetech seat will be! While the aluminum seats are cheap, you'll never see me put on in my cars!

Jon V

You don't gotta tell me... I bought a pair of Sparcos

slammed_93_hatch

IMO that bar in the picture you posted is pointless. It is supposed to support the A-pillar bar, but it is so low that it isn't going to do anything the A-pillar still could collapse and crush your head..

Also that bar is bent, i have never seen one bent before and don't understand why it is bent.

Jon V

Like I said it is mainly there for ease of getting in and out of the car, non structural... These guys are like mid 40+ they need all the help they can get... Even with the door open it is a tight fit between the nascar bars, seat, and the hardtop. So he thought the "handle" would make it easier to get in and out. It's bent to clear the dash while not obstructing the path in and out of the car. S2000's don't have much room you know... LoL

Johnny Mac

Whether you know it or not, that bar is structural despite your intensions. And that extra bar will help resist a higher impact load on the A-pillar bar although due to fact that it is bent, the max load it can resist is reduced compare to a straight bar.

Sometimes, people can add a bar or stiffener to a structure that can actually reduce the strength of the structure. So it is important to understand how adding or subtracting members affects the integrity of a structure.