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Thread: Stretch questions

  1. #1
    Junior Member
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    Oct 2012
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    Stretch questions

    Hi all,

    I'm looking to start a custom project and had a couple of questions about stretching. Essentially I wanted to know how the stretching process affected structural rigidity and strength. I can't seem to find any good resources on that. Of course the person doing the work factors in to the answer massively, but are stretch jobs generally considered weaker or stronger than OEM.

    Essentially when I'm done I'd want the car to be track worthy, and of course chassis strength is a huge part of that. I won't be doing the work myself, of course, so that brings me to the question of if anyone knows a highly professional outfit that can do stretch work in the San Francisco Bay Area, or even at least in California some where.

    Thanks in advance for any insight!

    S.

  2. #2
    Senior Member dratts1's Avatar
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    Mar 2003
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    Depends on how much stretch you want. You can stretch the cradle rather than the frame and move the strut tops back 3" for a 355. After that you pretty much get into cutting the car in half and welding in whatever length you want. Roadsters need a lot more reinforcing, whether stretched or not.

  3. #3
    Junior Member
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    Oct 2012
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    Hi dratts1,

    Thanks for the response! I'm actually stretching a Porsche Boxster (986), which I know has started to become a relatively popular car to do this on. I've seen several companies do it, and have seen the YouTube video of it being done too. However, what I'm not sure here is the strength of that modification. I know there will not be any actual DoT-style crash testing, but what I'm not sure about is whether or not anyone has run the numbers on things like yield and tensile strength, sheering forces, etc, to calculate box material size, thickness, composition, etc. Also, I wasn't sure if there were any federal legal guidelines around stretching a vehicle (with all the stretch limos out there I hoped there would be), and what those standards/guidelines might be.

    Essentially I wouldn't be stretching more than 10-12".

    The reason I'm so particular about this is because it seems that most people who do these stretch conversions do it purely for cosmetic, practical space or to get the length as close to another vehicle for replica reasons (again cosmetic), and I haven't seen anyone talk about actually doing it for performance reasons (longer wheelbase, more engine space for bigger power, etc). When doing it for performance reasons you have to worry about motor torque, lateral G forces, vertical G forces, vibration, etc.

    Thanks again for the help!

    S.

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