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Post by sblast25 on Dec 28, 2012 14:16:34 GMT -5
So I want to make my justly crash safer, I love her but I have nightmares about getting in a crash with her. I'm in the snow and dirt roads all the time.
Anyways .. my plan was just to build a brush guard and bad ass bumper.
So I guess my question would be, Would a reinforced bumper and brush guard do much for crash safety,? Is there any other mods that would help? Maybe some reinforcements welded under the hood? Roll cage?
What about the frame? Is there any reason to or way to reinforce the fram?
It sounds funny but my theme for my justy is " small tank "
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Post by Armageddous on Dec 29, 2012 1:48:29 GMT -5
Adding a large bumper just make more metal for "whatever it is you hit" to become forced into you and your vehicle. Your best bet is a roll cage to stiffen the structure and save you if you flip. The roll cage will help your car resist compacting in a crash, and you could tie it to your rad support.
Terry
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Post by 88alex on Jan 3, 2013 0:43:49 GMT -5
But if you plan to go off roading a bumber to bumb trees an rocks with an not care would be nice an a brush guard to mount a wintch to would also be nice
I think I know what I'm going to make next now lol
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Post by nipper on Jan 4, 2013 0:30:36 GMT -5
:ets start with what kind of crash are you most worried about, as they did very well in thier time in crash tests
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Post by madmatt on Jan 10, 2013 21:46:55 GMT -5
Terry, I'm going to rebut your comment regarding tying the cage into the rad support... Typically cages are designed to protect the occupants, and as we know, the front of any modern car is a "crush zone", designed to fail in a predictable manner and dissipate energy into the deformation of the structure. Adding a cage, and then tying it into the front of the car, ahead of the strut towers would seriously negate the effectiveness of the crush zone. In any reputable rally cage design -one that would pass inspection by a governing body - cages may be tied into the strut towers, but not beyond. This is to allow the engineered portion of the body shell to work as intended. I make the rally comment because unlike circuit racing, rally involves objects like trees and rocks (substitute oncoming traffic) Circuit racing rules are vastly different where the car is traveling "down" a wall and the likelihood of head-on collision is very low. Also I will re-state as I mentioned earlier in NOAZ's thread, cages are great, but really not intended for street use. Unless very well designed (which is atypical outside of governed motorsports), they intrude into the occupant space, and a mild roll over can have you "wacking" you head against a bar that wouldn't normally be there. Caged car= helmet... unless the cage is non-obtrusive into the cabin, and is protected by proper high-density impact absorbing foam. To the OP, do you want to make it safer for you? or for the car? Matt
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Post by Armageddous on Jan 10, 2013 23:33:52 GMT -5
His concern was with making it "crash safer", a roll cage would achieve this, no? It's not ideal but let's face it, the Justy is a tin can, usually a rusty one, and if you crash in it you're probably going to die. I would take a roll cage over nothing. Terry
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Post by Deleted on Jan 11, 2013 16:24:42 GMT -5
but let's face it, the Justy is a tin can, usually a rusty one, and if you crash in it you're probably going to die. Agreed, you've got to be honest about what you got. I think Matt brings up a lot of good points. I have ruminated over this for a long time. subarujusty.proboards.com/index.cgi?action=display&board=talk&thread=3366&page=1I have been planning on doing a lot of these mods myself, but the Justy has a lot of constraints. Mostly this is due to the fact that the body is made of really thin sheet metal and the car was not over-designed or over-built to adequately handle extra power or weight. I too, am scared of an accident or roll over in a Justy. I am about 6" 2" tall and sitting in the car with the stock seats, if I lean forward without hunkering down a bit, my head with hit the ceiling pretty quickly. I put lower seats in, so it's better now but if I put a roll cage in it there would be a lot of head-to-cage exposure. Another thing you have to think about is weight. A steel roll cage will add noticeable weight behind the crush zone relative to the weight of the Justy. I understand the sentiment of wanting a "small tank", but to do that correctly I think you would really need to build a subframe, which would alter the crash characteristics of the vehicle but would allow you to build whatever tank-like features you want. It's a different strategy for crash worthiness: brute force vs. engineered destruction. It would be like a little truck with independent suspension. I would recommend a brake and suspension upgrade as well to handle the extras. I am not saying a roll cage can't be done safely, but you would really need it to be well away from head zone and be as light as possible. As far as the bumper is concerned, I am using Fiat bumpers so I am going to build a steel frame bumper mount with d-ring recovery points and a hitch receiver. The Fiat bumper will bolt onto the frame mount as well. This will also stiffen the frame quite a bit. To attach the bumper mount to the body, I am probably going to drill two through-holes horizontally through the front uni-body frame and use steel plates to sandwich the frame to distribute force over as much of the frame as possible. I think I can do all that in front of the crush zone, but I haven't looked at it for a long time. If it is necessary to impinge on the crush zone with my bracketry, then I will try to build some crush zones into them. One thing that I think can make a big difference are seats and restraints. The stock Justy seats and seat belts and open cabin design means you'll bounce all over the place in a serious crash.
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Post by madmatt on Jan 11, 2013 19:25:07 GMT -5
For sure the cage would make the car stronger, but how that relates to safety is depends on the accident type… You guys should drive a well caged Justy if you ever have the chance! You would probably not believe it was the same car! My cage is "ok" by current standards, but leaves a lot on the table that could have been done, and would not pass inspection today (7 years later), it is however "grandfathered" so I don't have to worry... The cage adds so much rigidity to the car it makes the suspension actually work! I look for things to hit just for fun! My point is that there are a lot of "cages" built that are probably unsafe, and with poor welds and poor design are accidents waiting to happen. I'm going to ramble a bit so bear with with me... A cage that only protects the occupants and does not protect the body shell would probably have little detrimental effect in a crash, and likely help reduce the likelihood of an injury from "intrusion" or crushing. Any strengthening of the bodyshell outside of the cabin would reduce the ability for the car to crush. Again not saying this is a bad thing… just stating. Race car cages have become so stiff that now beyond just 3" 5 point belts, we have HANS or similar devices because, with the weight of a helmet in a forward crash, the car is stiff, the belts work, and the helmet tries to yank our head off… now our head is essentially in a seat belt too! In our case I wanted a stronger front end as a poor landing shorten the car by about an inch… so after pulling the frame rails straight I added plate to the vertical portion up to where the axles pass through. The upper frames (inside the fender) I left alone. In my mind I have strengthened the suspension area, but the front of the car will still collapse if needed. Then there’s the story of the crew that built a massive skid plate, that in a front-on collision with a tree (I believe) forced the motor into the cabin area (through the firewall) rather than down under the car… broken legs were the result in a crash that otherwise may have been injury free (as I understand it…) It’s all very complex, so much so that even engineers and scrutineers debate some of the designs. For example, door bars being built in an “x” fashion became all the rage for a while. This directs forces from the front strut tie-in through the front cage leg, down the door bar and into the feet at the bottom of the hoop. Great! However, to “x” the door there needs to be a joint where the x meets. In a side impact this joint is a likely failure point, and a few folks got sharp, broken steel implants in their legs… so the X thing is being reconsidered, and strangely enough… the way I did our car, with 2 straight bars, is back in vogue… When I built our cage, I was told to use a steel gusset welded to the centerline of the bars in the corners of the windshield… now that’s a thing of the past, because it’s stupid. It loads the center of the tube and crushes it. Instead, the “taco” gusset is used, where a much thinner piece is wrapped like a taco in the corner and welded to the sides of the tube. Anyway, I guess my point is that a cage is good, but there are inherent changes to the car that in some cases may make it less “safe” Again, accident type dependant. If our OP wants a stronger car, by all means add steel where it counts! Bla bla bla bla…. Matt
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Post by madmatt on Jan 11, 2013 20:26:00 GMT -5
Bla bla bla bla...
The cage is actually pretty light. I used DOM 1.75" and I don't think there's 100lbs of steel in the car even with all the extras.
If you go back and look at Warwicks cage "new rally build" you see a well laid out hoop. In his t-bone accident the cage may have done a bit, but probably not A LOT as there was not yet an x in the hoop. It would work great in a roll over, but in his case the hit from the side, the long tube just bent...
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