Improving Safety on the S30?

[mom'sZ]

What if you cut a hole in the back end of a door and slide in a 1.5" tube and weld it on the front and back sides of the door frame with some steel plates on the end?

OTM: I think this is a good idea. I think I may have even suggested something like this in another thread. Done right, it could really help with side impact. There might even be room for two bars in there. The most important aspect would be to try to make the bar and it's mount plates wider then the door opening in the body. If you look at most modern cars, a lot incorporate aircraft style doors. It helps aerodynamics but it's also a safer design for side impacts. The door itself is much larger then the opening it goes in and overlaps the body as much as 3 or 4 inches all the way around. That makes it harder for another vehicle to penetrate the cabin. The unibody deforms, but the door doesn't push through.

The main problem with a full cage in an S30 is that the interior area is small. The roof bar running from the main hoop to the a pillar area has to go by your head, depending on how tall you are and how low the seat is, with in inches of your head. Like BJhines has pointed out and I can confirm, your head often touches the bar. There is no other place to run it.

[sonomaz]

This is the second time in two days I have seen some amazing pics of S30 sheet metal that is invaluable to all of us. Those door pics are excellent in showing how little there is between your left elbow and the car in the next lane. The other thread was "1971 240z restoration PICS" by wickiewicked240z. I think both of these threads should be stickies because of there valuable pictures.

 

The tube in the door got me thinking. I like that idea alot, but, if it holds you put all the force on the door jam. On page three of this thread Austin240Z posted the pic of the wrapped up Z and it does not appear that the front door jam held. It looks like the dash (I’m assuming, can't really see it), front door jamb, "A" pillar and cowl all collapsed. Granted a Hummer is not a telephone pole and vice versa, but it does make you wonder if the tube in the door is enough.

 

Paul

[johnc]

This thread is turing into an internet engineering masterbation exercise.

 

Its next to impossible to get OEM crash data and the data for the 240Z is long gone. Our only real source of safety modification data for our 35 year old cars are the racing sanctioning bodies. Look to their rule requirements for side impact protection.

 

Welding a bar into the door that's not design to handle the additional load is foolish. Welding a bar into a rocker panel that's below standard bumper height just adds weight to the car. Adding a door bar to a roll bar (6 point setup) without additional floor pan reinforcement or a knee bar is a leg crusher.

 

SCCA has this stuff figured out. GCR section 18.

[Daeron]

Its next to impossible to get OEM crash data and the data for the 240Z is long gone. Our only real source of safety modification data for our 35 year old cars are the racing sanctioning bodies. Look to their rule requirements for side impact protection.

 

John: I couldn't agree more, thank you for the response.

 

Welding a bar into the door that's not design to handle the additional load is foolish. Welding a bar into a rocker panel that's below standard bumper height just adds weight to the car. Adding a door bar to a roll bar (6 point setup) without additional floor pan reinforcement or a knee bar is a leg crusher.

 

SCCA has this stuff figured out. GCR section 18.

 

Thank you for chiming in; Your data are sufficient and your reasoning for relying upon that data is probably the safest way to proceed in any case.

 

I never personally thought much of tubes inside the door.. I was thinking something more like the stock reinforcement. Basically a thin gage sheet metal "box" or channel, about a half inch "thick" (thickness between one face of sheetmetal and the other) to attempt to absorb a small amount of inertia; no more than a pound or two of steel added to each door to give just a tad of additional metal in there to help resist SOME deformation.

 

The point made about the door shape was my greatest hesitation for any in-door reinforcement; but I couldn't phrase it well enough to make the argument here. As for the rocker reinforcement, I quite simply hadn't thought of the fact that bumpers are higher than that.

 

I guess that image of the one that wrapped around a telephone pole/tree is really stuck in most of our minds.. and thats about the only time reinforcement that low would help at ALL.

[johnc]

I guess that image of the one that wrapped around a telephone pole/tree is really stuck in most of our minds.. and thats about the only time reinforcement that low would help at ALL.

 

An accident like that is a rare occurance, that's why it sticks in our minds. The majority of accidents involve the front and rear of the vehicle. I don't know what the percentages are but someone posted links to the government data somewhere above. A perfect 90 degree side impact that hits squarely in the door and misses the rear wheel well or the front firewall is also a very rare occurance.

 

These rare occurances tend to focus our attention beyond any reasonable evaluation of the chance of it happening. Its like airliner crashes. They are horrific when they occur, but you have a better chance of dying from bee sting then getting killed in a plane crash.

 

Time and effort to improve the safety in a 240Z would be better spent on a properly mounted FIA approved race seat and a DOT approved 4 point harness system. That would do far more then adding door bars, subframe connectors, or rocker bars because the seat and harness will help protect you in ALL accidents, not the rare freak ones.

[OlderThanMe]

I thought the 240s and early 260s had the doors with NO reinforcement, and the 280s had the reinforcement.

 

I have an early 260 built in 11/73 and it has a type of door bar. Not like the empty 240z door there but definitely not as stout as that 280z door.

I'll get some pics tomorrow. I still don't think it would help much in a Z vs. SUV match...

[Tony D]

Yes, since I've been accused of being pedantic in the past here, I'll clarify that I was referring to the latch switch as you supposed. Internal structures are bollocksed up anyway, the US doors are impossible for my hands to fit inside and do any appreciable work... I hate the door beams for that reaason alone! not to say they are bad. just makes working inside the door impossible for my hamhock hands.

 

The latch I would assume was a hand-in-hand change with the improved door beam, but not to say 'build out cars' don't exist. I would venture to say the later latch design would give optimal integrity in conjunction with the door beam of the latest design. Earlier cars with that same 'improved beam' and the older latch obviously will not have the same door-closed-during-impact integrity (which is the reason for the enclosed latch). Better than the previous design, of course, just not 'the best'. Ultimately for an early car, the later doors (pre 6/76) with the heavier door beam would probably give you the best door available from a safety standpoint of integrated engineering. But like BJ Mentioned, the doorbeam is pretty darned low to do any good against anything but another Z on the track...

[Tony D]

These rare occurances tend to focus our attention beyond any reasonable evaluation of the chance of it happening.

 

I can't remember now if I posted in this thread or not about engineering for reasonable eventualities as opposed to every eventuality, but this indeed goes along with what John is saying: there will always be something so horiffic so as to draw your attention and make you go 'I don't want that to ever happen to me!'

 

But you can't live like that---life isn't safe. You just have to take your reasonable risks. Reasonable doubt has turned to 'beyond any shadow of a doubt' today. And that's unreasonable.

 

Prep soft, belt tight, and minimize impact angle to draw out collision time. When it comes down to it, take the hit anywhere BUT the driver's door, and do whatever you can to position the vehicle like that. Sometimes you can, sometimes you can't. You do what you can, when you can, and that's all you can hope for.

[Daeron]

I can't remember now if I posted in this thread or not about engineering for reasonable eventualities as opposed to every eventuality, but this indeed goes along with what John is saying: there will always be something so horiffic so as to draw your attention and make you go 'I don't want that to ever happen to me!'

 

But you can't live like that---life isn't safe. You just have to take your reasonable risks. Reasonable doubt has turned to 'beyond any shadow of a doubt' today. And that's unreasonable.

 

Prep soft, belt tight, and minimize impact angle to draw out collision time. When it comes down to it, take the hit anywhere BUT the driver's door, and do whatever you can to position the vehicle like that. Sometimes you can, sometimes you can't. You do what you can, when you can, and that's all you can hope for.

 

 

A-men. I just wanted to clarify that any comments I've made thus far in this thread were made while bearing ALL this in mind first and foremost. I accept every day in this world as a risk that it might kill me.. (living in south Florida, with drivers from every different part of the world AND the US.. it just blunt reality.) In my mind, if you don't wake up every day prepared to die, then sooner or later you're just going to be surprised. It isn't morbidity; I consider it my POSITIVE worldview....

 

and as for this...

...... the doorbeam is pretty darned low to do any good against anything but another Z on the track...

 

ach!! tragedy such as that should never be spake of!!!! Fie!!

[sonomaz]

Time and effort to improve the safety in a 240Z would be better spent on a properly mounted FIA approved race seat and a DOT approved 4 point harness system. That would do far more then adding door bars, subframe connectors, or rocker bars because the seat and harness will help protect you in ALL accidents, not the rare freak ones.

 

Well said John and that's where I hit a problem. I could not find DOT approved harnesses (maybe I didn't look hard enough) and Simpson clearly states they are not DOT approved. Replacement belts for a Z are old and used or if you are lucky to find them 35 year old NOS! Why wear these at all? So next issue is how do you mount racing harnesses? The stock location for the shoulder belt is no help and now you are looking at a modified roll bar that puts a steel tube 2 inches behind your head. What's a Z guy to do?

 

(I'm back on the "internet engineering masturbation" thing. Its a lot of fun!)

 

Paul

[johnc]

Schroth offers a number of DOT approved four point harnesses.

[JMortensen]

Once again, we need to keep in mind the intended usage of the guy who started the thread. Rocker bars might be fairly useless in a collision with another car. If the intent is to push your luck in the canyons, there are other considerations that rocker bars might be of some help in dealing with. I believe tube80z convinced Dave Kipperman to put the rocker bars in his car after seeing a hillclimb car go over the edge. In that case the guy's cage managed pretty well, but the driver's feet were smashed because the cage stopped at the front of the door. The intended usage is similar. And they will stiffen the chassis, as the rockers are the main structure that Nissan used to tie the front and rear of the car together. The rockers are more structural than the A and B pillars, or the sheet metal "frame rails" which don't even connect front to back in the stock configuration. Personally, you couldn't get me to push to 10/10ths in a canyon without a heck of a lot more than rocker reinforcements, but I think that point has already been made so I'll leave it at that.

 

As far as DOT approved goes, is that a legal requirement for seatbelts? If it is, my first inclination would be to adapt a seatbelt out of a newer car. I had a friend with a 510 who got some belts out of a vanagon if I remember correctly and adapted them in. The thing that he was after was a retractor which didn't bolt into a recessed area of the body.

[Zmanco]

If you are looking for replacement seat belts, I am using 3 point belts from Wesco http://www.wescoperformance.com. With these you have new webbing and mechanisms, and the fit into my 73 was quite good actually. They are retractable.

 

They're not a replacement for a proper racing seat/harness, but I'm sure they're safer than what I took out.

[(goldfish)]

As for me, I brought up the rocker question because, my doglegs need to be replaced, I'll be in that area, It will give a good jacking place, and those pole pic's scare me.

 

If there are any good ideas to strengthen the doors against a car impact that doesn't affect DD usability, I'm all ears.

[Tony D]

Schroth offers a number of DOT approved four point harnesses.

 

John beat me to it, Schroth makes the only OEM style three point replacement belt kits I would consider for the Z. They have some VERY nice products available, and like anything good....well do I really need to say the words:

 

"How much is your life worth?"

 

One thing I will add about the guy in Holland who works for the Paris-Dakar Prep Company...he is the panelbeater for the company, and is making aluminum hood and door skins for the vehicle---the guys intention for the rocker panel bars was more ersatz tubeframe than safety. The guy wants to be able to alter any aspect of the monocoque without comprimising the integrity and stiffness of the chassis. Basically 'A Z Skin' to play with as a panelbeater with time on his hands would see fit. It just happens that it's an FIA approved Cage Engineering works, so he has a LOT of competent oversight in the shop to help with his toy. I will have to find the photos and post them.

[Bartman]

I've heard that Schroth makes 3-point harnesses that fit in our Z's in the past, but I can't find them listed on their web site. If you go with a 4-point, is there any way to install them without using a roll bar?

[Zmanco]

For a 3 point belt, how is the Scroth better than something like the Wesco?

[Tony D]

Never heard of Wesco, will have to see their product. I have installed Schroth in the past, and it was a very high quality piece, and for a LONG time was the ONLY manufacturer that had DOT/FMVSS approval on their belts (which evolved through their passing the German TUV approval process to sell their parts in native Germany).

[JMortensen]

I've heard that Schroth makes 3-point harnesses that fit in our Z's in the past, but I can't find them listed on their web site. If you go with a 4-point, is there any way to install them without using a roll bar?

Weld in a rear strut bar.