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Never Thought I needed a chassis Jig

Discussion in '206/246' started by swift53, Nov 8, 2018.

  1. swift53

    swift53 F1 Rookie
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    Nov 17, 2007
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    Alberto
    03724 has a slight kink in foremost part of the chassis on the oval tubing
    in front of the radiator, nothing huge, but sufficient. Someone else, not us, laid a chain
    (link mark) on it, and tried pulling to straighten.

    Evidently was not very good and the repair was not properly done.

    Any thoughts on how to hold the chassis very firmly and level to the ground,
    to then exert force in the down direction?

    No frame machines here that can trust, or even leave the car unattended :)

    What I have is a 4" concrete slab that I can drill, cut, anything you want to install,
    something or other.

    Thank you,
    Regards, Alberto
     
    prober34 likes this.
  2. pshoejberg

    pshoejberg Formula Junior
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    Dec 22, 2007
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    Peter H
    You need one of these Alberto:

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    Used the bench for exactly the same purpose, rebuilding the right-hand side oval pipe chassis on my 512bbi. I held the chassis fixated while changing out two damaged sections of the oval tubing and completely rebuild the light secondary front chassis holding the hood and cooler etc. It was possible to work with tolerances smaller than 1 mm using the bench as reference. I never had to pull in anything as the chassis was dead straight (Sometimes you’re better off trying to straighten using heat rather than force on a tube chassis). The bench was bought from an auto shop and it was cheaper than what materials would have been if I chose to make one myself. They are hidden away in the corner of a lots of shops and are hardly being used any more due to the fact that it is cheaper to buy a new car than using man hours on complex repairs. It is shame that we live so far apart since my bench is available now. Maybe you can buy some train rails locally and construct something similar...-:)
    Best
    Peter
     
  3. Nuvolari

    Nuvolari F1 Rookie
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    Sep 3, 2002
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    Rob C.
    Alberto if you have a very flat concrete slab then you can start by using it as a surface plate to determine where the deflection of the chassis is. Start by creating some equal length steel supports (at least 4 of them) you can place on the slab and then rest the main chassis tubes on. The center section of the chassis should be flat and square. Assuming that the concrete is flat and the chassis rests evenly on your 4 supports you can then start measuring down from the other parts of the chassis to the concrete to determine how far off the chassis is. Peter is correct that force is not always the answer and careful heat sometimes combined with making a relief cut that you then weld and grind flush can achieve great results especially when you lack the correct pulling hardware. I would start with determining the exact deflection and location of the bends before committing to pulling on the chassis.
     
  4. swift53

    swift53 F1 Rookie
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    Alberto
    Thank you Rob and Peter! Great observations...
    I will start easy, and make the frame, shim it then measure.
    Will keep you posted.

    Regards, Alberto
     
  5. dgt

    dgt Formula 3
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    Jan 14, 2011
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    Andrew
    Alberto, remember the platten in my shop?
    Get one of those....
     
  6. swift53

    swift53 F1 Rookie
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    Alberto
    Here? o_O

    Regards, Alberto
     
  7. dgt

    dgt Formula 3
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    Jan 14, 2011
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    Andrew
  8. swift53

    swift53 F1 Rookie
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    Alberto
    Cannot even begin thinking where I might find one here,
    and if it ever existed, it has been melted into re-bar...

    By the way, that, is not Andrew in the car, it was an illegal alien working on a strange car ;)

    Regards, Alberto
     
  9. Jon Hansen

    Jon Hansen Formula Junior
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    Feb 6, 2007
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    Jon Hansen
    #9 Jon Hansen, Nov 15, 2018 at 10:11 PM
    Last edited: Nov 15, 2018 at 10:24 PM
    Drill an anchor into the concrete below the kinked section of frame.
    Wrap a protected chain or weld a pull tab forward of the kinked frame section and attach a short section of chain to the anchor. The farther forward the more leverage you get.
    Place a floor jack with a properly made support under the kinked section.
    Exerting upwards pressure with the floor jack becomes downward pressure once the chain is tight.
    Heat, jack, measure as necessary until kink is straight.
    It may be necessary to install one more anchor at the rear of the car to hold it down in position while you are exerting pressure.
    If you pull too far down, reattach to the anchor further back, and use the floor jack to push up while holding the car down.
     
    swift53 likes this.
  10. synchro

    synchro F1 Veteran

    Feb 14, 2005
    8,665
    Seattle&PHX
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    Scott
    I had an ugly chassis; the rear cross brace with those 2 engine mounts had been high sided, the Oval rear chassis tube was horribly dimpled and I wanted it better than original.

    Dennison International (http://qualitythatgoes.com/) has a laser flat jig they purchased from The Boeing Company from prior 747 cockpit assembly. In addition they have the skill, staff, equipment and metric square tube to do the job. I found Dennis McCaan had a 6' section of OVAL Dino Chassis Tube left over from his personal restoration (I still have some left) and it all came together. They secured the whole chassis of 05702 to the jig and my Dino received the full chassis spa treatment :)
    Very pleased with everything they've done, can't praise them enough
     

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