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Thread: Safer? Fiero or Custom Chassis?

  1. #1
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    Safer? Fiero or Custom Chassis?

    By DOT standards for the kit car world. Which is safer? A Fiero with a professional stretch like IE performs, or a tubular or square frame chassis like CHassisWorks or Cliffscustoms? I ask because i don't know how a stock Fiero ever performed in front or side impact crashes, and from the looks of the custom frames i've seen, none really have side impact protection save for what small pieces go in the doors. Are custom chassis's designed with some sort of crumple zone CAD design to manage impact like modern passenger cars, or are they built as rigid as possible to accomodate performance alone??

    I think its a pretty important discussion, before I make my final choice on my build I'd appreciate anybodies ideas. Thanks

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    Re: Safer? Fiero or Custom Chassis?

    It matters what kind of kit you are talking about. I assume you are discussing Lambo.

    First lets talk about side impact, the only side impact is what is put in the door no matter the chassis decision. The fiero doors are not retained so that is not an issue.

    Second, a third or so of the fiero strength is in the roof structure, well more precise the roof is in compression or tension according to the load. Once the roof is removed there is alot of things that can be done to regain some of that strength. But they are never the same again in my opinion. I have driven quite a few, with x-braces, with triagulated tube along the rockers, etc and the all feel a little "soft" to me.

    The other issue with Fiero for Lambo is no matter what you do they sit you up a few inches higher in the floor and the footwell area is really tight. because as you shift the sitting position forward the foot well does not move. The replica chassis has several more inches of headroom due to the floor being lower and the footwell is much larger. The chassisworks chassis is in between the fiero and a replica chassis.

    Safety, it is only as good as the guy building your chassis, fiero, chassisworks, or replica. I do know the chassisworks and replica are a lot stiffer than a fiero with no roof.

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    Re: Safer? Fiero or Custom Chassis?

    On my chassis works chassis the doors will have a 1" crash bar from hinge to latch. leaving the roof structure which will be d.o.m. round tubing so it will be safe. both of the mods can be done to the fiero too. Those are the only 2 crash structures i know of on the frame that are tampered. others are the collapsing column, and hood ripple. both will be on my build by not cutting the steering column and putting precise cuts in the hoods steel brace so when impacted it will curl instead of go thru the windshield and cut your head off

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    Re: Safer? Fiero or Custom Chassis?

    id also like to add the gains from a tube chassis would be, ability to lower floor for head room, more engine bay room for v12, and better suspension stifness for race. last the ability to modify

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    Senior Member AdrianBurton's Avatar
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    Re: Safer? Fiero or Custom Chassis?

    It will depend o the kit you are building like Bartman said. If you are using the fiero without major mods the fiero was the 2nd safest in the world, but if you are removing the roof all bets are off.

    Having said that you can make a tube chassis safer than a hacked fiero, you will not be bound by a pre-existing chassis without adding the weight the fiero will require to reach the same level of safety.

    GMG:

    You may want to make sure your design allows for deformation in the event of a side impact, otherwise you run the risk if being trapped in your car.

    Adrian

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    Re: Safer? Fiero or Custom Chassis?

    Quote Originally Posted by AdrianBurton
    It will depend o the kit you are building like Bartman said. If you are using the fiero without major mods the fiero was the 2nd safest in the world, but if you are removing the roof all bets are off.

    Having said that you can make a tube chassis safer than a hacked fiero, you will not be bound by a pre-existing chassis without adding the weight the fiero will require to reach the same level of safety.

    GMG:

    You may want to make sure your design allows for deformation in the event of a side impact, otherwise you run the risk if being trapped in your car.

    Adrian
    Whats the best way to do that?

  7. #7
    Senior Member AdrianBurton's Avatar
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    Re: Safer? Fiero or Custom Chassis?

    Quote Originally Posted by Greenmeansgo
    Quote Originally Posted by AdrianBurton
    It will depend o the kit you are building like Bartman said. If you are using the fiero without major mods the fiero was the 2nd safest in the world, but if you are removing the roof all bets are off.

    Having said that you can make a tube chassis safer than a hacked fiero, you will not be bound by a pre-existing chassis without adding the weight the fiero will require to reach the same level of safety.

    GMG:

    You may want to make sure your design allows for deformation in the event of a side impact, otherwise you run the risk if being trapped in your car.

    Adrian
    Whats the best way to do that?

    There are a few, one is to attach your bar to a sheet metal bracket that will "unfold/ stretch" under impact. think accordian it should give you 3-4" crush.

    That is probably the easiest

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    Re: Safer? Fiero or Custom Chassis?

    I was thinking of composite doors? Instead of just fiberglass, what about a very substantial layup of carbon/kevlar on the inside of the door and the door liner?

  9. #9
    Senior Member AdrianBurton's Avatar
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    Re: Safer? Fiero or Custom Chassis?

    The problem is the door cannot be "TOO" strong, it has to give, to absorb the impact energy. The risk that you run is in pinching the door opening closed, pulling the hinge toward the striker and wedging the door closed. That is why it has to give

  10. #10
    Senior Member AdrianBurton's Avatar
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    Re: Safer? Fiero or Custom Chassis?

    have a look at what lambo did

    http://www.flickr.com/photos/adrianburton/4123872094/



    Notice the attachment point for side intrusion, it is not at the latch. In the event of a crash the door frame will get pulled in and still allow door function.

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