Side intrusion bars

[PeterAllen]

Originally Posted by Zedn

What stops your car from moving sideways in the direction your hit? ..

A tree, e.g. '0.05'.

[xlr8tr]

Originally Posted by PeterAllen

A tree, e.g. '0.05'.

well said- or a guardrail, or wall, or.....

[Zedn]

Originally Posted by xlr8tr

well said- or a guardrail, or wall, or.....

I think we are talking about different things. Im talking about side impact from a vehicle.

That may happen if you slid sideways into a pole or similar. If you are in this position then the bolts will be least of your worries. For that sort of collision you actually want the side intrusion bars to deform a bit to absorb energy.

First of all you are assuming that the side impact is a very narrow object that only impacts the door. In reality this is very unlikely to happen due to the size of cobra door (or ferrari).

If a car is hitting you from the side you are in most cases going to be crossing an intersection where you are both crossing paths (such as someone running a red light). In this case there will not be trees or walls in that direction, there will be road. If it is a T intersection it will be very unlikely they will t bone you. You will t bone them or run up the back of them.

This link will show you why i talk about tyres. Select tab for side impact test and press play. Notice what the car does when tested. The impact is absorbed by both the friction of the tyres and crumple zone of the front of the other car.
ANCAP - Crash Testing Explained.

You also need to consider what is going to happen to the driver. In a cobra, the top edge of the door is quite low. When the car is hit from the side the driver will be whipped towards the incoming car. If it is a 4wd it may go over the bars.

There is much more to crash science than a point load in the middle of a side intrusion bar. The shear capicity of each bolt in the striker is several thousands Kgs. The full impact is also not applied only on the bolts it is also carried by the hinges and any other part of the car that is hit.

There is also the thicknes of the striker plate/latch to consider as it is probably less than the bolts

[PeterAllen]

Zedn - I agree with what you are saying but I think you are talking about a best case impact scenario. If I'm in the position of starting to fit the intrusion bars I would like to think I could design for the worst case scenario and work down based on the limitations I encounter.

After reading John Wilson's newsletter I understood I should ensure the intrusion bar does not inhibit the ability of the door and hinges to hold the door in place in an impact. However, when I spoke to someone at the Transport Dept today they were telling me to attach it to the hinge and the door latch. Am I reading John's newsletter correctly? - I'll check the actual ADR later.

I don't want to be morbid about this but did anyone see the Daytona after Brock's crash, or any Cobra with a pole side intrusion, to see if the hinge and/or latch were torn from the fibreglass door. I'm not disputing the strength of the bolts; I'm just trying to understand the weakest point in the whole door structure. Does fibreglass act as a good impact attenuator or does it tend to shatter?

You are correct that the occupant of any severe impact will experience hyperflection of the neck in the direction of the impact and that's why most race cars have halo head rest and those neck thingo attached to their helmets and held in place by the seat belt. Since the introduction of headrest the term 'whiplash' seems to have disappeared in relation to rear impacts - all a little off the topic of intrusion bars.

[Outwest34au]

What I am preparing for with my mod is the stupid wench who has a hubby working at the mines and therefore must drive a prado. She naturally is more worried about her social life, nokia and the kids in the back than the traffic around her, Because we live in a relatively rural area there is no need for her to look properly at intersections or even use indicators, Yes there is a good chance her shiny chrome like bullbar will over ride the top of the door, I just hope I see it coming and can lay down across the seat in time, (it's worked before for me).

The way I see it with side vehicle impact the object of the game is to spread to load across a wider area, Sure, if the door is hit by a point at the latch area it may well fold inside the Cobra. If it is hit relatively squarely let's hope the Cobra is picked up and scooped sideways. Everything is a compromise and not every possible incident can be catered for. What happens if a roo jumps in the side of the car with me while cruising home at 100 kmh on the highway?? Unlikely? Not really, I've had a few strike the side of the front gaurd and door, even had a mad emu double back and squarely hit the passengers door on an old dato ute near Barcaldine.
From my brief look at the link for the Dato bars Peter posted the bar pretty much does join from the hinge AREA to the latch AREA. And not a real solid looking bar at that.

I have hit a pole sideways at 90 mph in canberra, one of the big double poster signs at a roundabout, 4 inch poles with 3 ft of cement on each, pulled them clean out of the ground and destroyed the RX3 Savannah, sideways, upside down, spinning on its side, all but tearing it in half. I have also been T boned in a mazda capella 1600 and it was a totally different experience, just slid the car across the road and as I bounced off the other car kept travelling relatively in the direction I had planned.

As much as I plan to stay prang free in the Cobra I would more fear a clown in a car T boning me than an out of control tree jumping into the side of me.

Best you fit into what the rules require and take any extra precautions by design as you see fit.

[Zedn]

Originally Posted by PeterAllen

Zedn - I agree with what you are saying but I think you are talking about a best case impact scenario. If I'm in the position of starting to fit the intrusion bars I would like to think I could design for the worst case scenario and work down based on the limitations I encounter.

After reading John Wilson's newsletter I understood I should ensure the intrusion bar does not inhibit the ability of the door and hinges to hold the door in place in an impact. However, when I spoke to someone at the Transport Dept today they were telling me to attach it to the hinge and the door latch. Am I reading John's newsletter correctly? - I'll check the actual ADR later.

I don't want to be morbid about this but did anyone see the Daytona after Brock's crash, or any Cobra with a pole side intrusion, to see if the hinge and/or latch were torn from the fibreglass door. I'm not disputing the strength of the bolts; I'm just trying to understand the weakest point in the whole door structure. Does fibreglass act as a good impact attenuator or does it tend to shatter?

You are correct that the occupant of any severe impact will experience hyperflection of the neck in the direction of the impact and that's why most race cars have halo head rest and those neck thingo attached to their helmets and held in place by the seat belt. Since the introduction of headrest the term 'whiplash' seems to have disappeared in relation to rear impacts - all a little off the topic of intrusion bars.

Im not sure what you mean about the newsletter. It says that it must be designed so that the bars cannot enter the vehicle without destroying the body work around the hinge and lock. I interpret that as destroying the subframes that the hinge and striker plate are mounted to on the car (not the door).

If the bars and latch are not integral then the bars will be able to enter the cabin.

I think the best way is as i originally said with the hinges mounted to steel plate and intrusion bars welded to the plate. Same on the other side with the latch bolted to it. For your adjustment, perhaps you could slot the holes in the plate and use a bolt and nut. Or slot the holes in the hinges and tack nuts onto the steel plat in the door.

Effectively you should be able to open and close the intrusion bars without the door there. That way the door is just glassed on to the frame for the intrusion bars.

[PeterAllen]

Originally Posted by Zedn

...If the bars and latch are not integral then the bars will be able to enter the cabin....

Yep... agree entirely, but, and this is the point I can't quite get, by attaching the bar to the hinge/s and the latch you would be at risk of damaging them if the intrusion bar was impacted. As the hinges and latch are a separate ADR (to which my car already complies) to the side intrusion ADR then the intrusion bar should not function so as to inhibit the performance of the hinges and latch - that seems to be the way the rules read. I'm not saying I agree with it just that is how they read.

The RTA advised to go with your idea and if my engineer agrees I'll get it in writing from the RTA and move on to my next anxiety attack. Thanks all.
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[AC-460]

Peter I think you should just do enough to keep everyone happy......personally I think if you want to put in an extra 100kg of steel to withstand the unimaginable go right ahead ..But I personnally think the side intrusion bars are a waste of time ...I wouldn't like to be in the thing travelling side ways at a rate of knots and hit something ...intrusion bars or not you in trouble....

[Zedn]

Originally Posted by PeterAllen

Yep... agree entirely, but, and this is the point I can't quite get, by attaching the bar to the hinge/s and the latch you would be at risk of damaging them if the intrusion bar was impacted. As the hinges and latch are a separate ADR (to which my car already complies) to the side intrusion ADR then the intrusion bar should not function so as to inhibit the performance of the hinges and latch - that seems to be the way the rules read. I'm not saying I agree with it just that is how they read.

The RTA advised to go with your idea and if my engineer agrees I'll get it in writing from the RTA and move on to my next anxiety attack. Thanks all.
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I think you are misinterpreting it.

They cant interfer when in working condition not after an accident.

[Outwest34au]

If a plain sheet metal door gets punched in neatly by "an object" it will still distort the hinges and latch parts even if it doesn't have bars. Unless it's made of tin foil and just tears before anything else bends.
Latches must be burst proof, that means they are gonna hold as long as possible until the force overcomes the make up of them, by then you're toast anyway.

[Rob. Smith]

Just out of curiosity...my vehicle has intrusion bars...a Ford approved latch and matching catch...bolted securely to the chassis. The 3 bolts (screws actually) holding the catch are pretty small about 6mm / 1/4" so all depends upon these three bolts. On a steel body the door fits into a "socket" so along with the catch the door crushes up against a pressed and folded steel frame which helps in absorbing an impact. Fibreglass frames are stiff but how stiff ? Drive the Cobra like it was a motor bike...be aware and be defensive.

[Outwest34au]

Originally Posted by Rob. Smith

Just out of curiosity...my vehicle has intrusion bars...a Ford approved latch and matching catch...bolted securely to the chassis. The 3 bolts (screws actually) holding the catch are pretty small about 6mm / 1/4" so all depends upon these three bolts. On a steel body the door fits into a "socket" so along with the catch the door crushes up against a pressed and folded steel frame which helps in absorbing an impact. Fibreglass frames are stiff but how stiff ?

Re the socket and pressed frame, if I had a 32 mm CHS bar running along inside the door frame on the sill panel I would feel the system would be as good as it gets, something to stop it moving in. The door in a car like ours is only there to fill a hole and any load in my opinion has to be spread to the chassis, be it through the front hoop or direct to the chassis at the latch end.

Originally Posted by Rob. Smith

Drive the Cobra like it was a motor bike...be aware and be defensive.

I said that to my workmate as we drove home last night.
ADRs are for compliance, vigilance is for life.

[Aussie Mike]

I ran an extra 3x2" RHS section across between the dash hoop and the door lock pillar. This is in the section where the sill is so adds a bit more side impact protection as well as tying the dash hoop and the door lock pillar together.

There are 2 2"x2" sections inside the door between the door hinge and the latch. But the hinges are a bit lightweight in my opinion and I plan to add a reinforcement plate in there.



The beam is foamed and glassed in which should stiffen things up too.


I sill wouldn't want to be involved in a side impact crash in a Cobra as I reckon it would be messy.

Cheers

[Rob. Smith]

The RMC twin rail Chassis has the top rail of the chassis running where Mike put his extra bar. I still feel side intrusion is a bit scary......again the motorbike attitude.

[AC-460]

I agree with the motorbke theory....
That extra rail youve put in is at seat height.....if something collects you from the side or you slide sideways into something your body is going to be travelling towards the door....you will slide straight over the top of that bar...
an air bag is going to be the only thing that will absorb the impact....just a silly one maybe we should be filling the doors with styrene foam....!

[Outwest34au]

From this site, Texas Cobra Club section

I got T-boned yesterday pics

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[Zedn]

Originally Posted by Outwest34au

From this site, Texas Cobra Club section

I got T-boned yesterday pics

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Scary stuff. Lucky he is ok, could have been much worse.