Spaceframe race car chassis - options

  1. Cornwallfrank New Member

    Messages:
    12
    Location:
    Cornwall
    Hi all,

    I am considering building a Hillclimb/sprint spaceframed car. I plan on using the running gear/engine out of my existing car.

    I'm doing this from my own design, it will be a one off so the design detail will probably change during the build process as I realise I've missed things etc. The main chassis will be built from 3mm wall 50mm box section.

    As a non welder as I write this, my question is which would be the better way forward considering that the welding needs to be strong enough for the application.

    I am very mechanically minded and have built cars before, but not had to weld anything.

    My options are:

    I could teach myself/get taught, buy a decent MIG welder, practice practice practice and do it myself.

    Draw my design and get a professional to build it, the problem with this is design changes/alterations

    Or, is it feasible to tack together what I need, make changes that are required, re tack, and then either take it to a professional to complete the welding or use a mobile welding service?

    Your thoughts/advice will be appreciated.

    Thanks

    Frank
     
  2. MattH

    MattH Member

    Messages:
    3,463
    Location:
    Bristol
    Practice practice practice and then weld it yourself.
     
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  3. johnik

    johnik Member

    Messages:
    389
    Location:
    sunny Somerset
    get over to locostbuilders.co.uk, everything you need to know about building your own chassis / cars on there
     
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  4. Cornwallfrank New Member

    Messages:
    12
    Location:
    Cornwall
    Hi, Thanks for your message, I know the site well, mine is very much different from the Locost design, more of a rallycross silhouette car.
     
  5. Cornwallfrank New Member

    Messages:
    12
    Location:
    Cornwall
    This would be my preferred option, but not knowing how quickly I can get good enough is the worry!
     
  6. Lazurus

    Lazurus Member

    Messages:
    394
    Location:
    Norfolk uk
    As a fairly new Mig welder, it is easy to stick metal together, but making safe, structural good looking joints is a whole new ball game. Will your welds hold if it rolls, you could design , tack redesign and retack, them get a professional in to do the important structual welds.
     
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  7. Cornwallfrank New Member

    Messages:
    12
    Location:
    Cornwall
    That's my second favourite option, but need to see if the professional guys would be happy
     
  8. Cornwallfrank New Member

    Messages:
    12
    Location:
    Cornwall
    I will be getting the rollcage designed and fitted by a specialist as this has to meet Motorsport UK standards
     
  9. Wonderweaver New Member

    Messages:
    17
    Location:
    Manchester
    I'd go with the second option if I was you--just for the piece of mind . Go to fab shops at lunch time and ask a welder some will do it when the boss is out obviously cheaper.
     
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  10. MattH

    MattH Member

    Messages:
    3,463
    Location:
    Bristol
    Mig welding is just not that hard. Learn to do it properly and it’s a skill you will always have.

    A properly designed space frame should not be reliant on the welds to hold it together.
    Most if not all the welded joints should be in compression with a few notable exceptions.

    Some will be in shear but it’s not likely that they will be singular joints that could critically fail (think wishbone mounts of which you would usually have two on each wishbone).

    Maybe you pop a joint because of a cold weld. Grind it out and redo it.
     
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  11. daedalusminos Member

    Messages:
    563
    Location:
    Norwich
    3mm, 50mm box sounds substantial for a true space frame, nonetheless if it's steel then MiG would be the preferred option. As previously stated, not too difficult to get a strong joint, practice required for quality welding.

    Design on paper/CAD before you start cutting metal and you'll save yourself a wealth of time.
     
    Cornwallfrank likes this.
  12. Cornwallfrank New Member

    Messages:
    12
    Location:
    Cornwall
    I'm using the Motorsort uk Blue book for guidance, the floor frame for a rally cross car needs to be 2mm x 50mm box, but cant seem to find any in 2mm, have found 2.5. Above the floor frame I will go smaller where I can, The whole thing will be tied together with an approved ROPS, roll over protection system. So really its a floor frame, top suspension mounting positions, engine/gearbox and steering column mounts.
     
  13. 8ob

    8ob Member

    Messages:
    3,682
    Location:
    moscow on thames
    A good starting point if you want everything straight and square would be a gurt flat steel bench or slotted table.

    [​IMG]
     
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  14. spencer 427

    spencer 427 Member

    Messages:
    5,522
    uk colchester
    Location:
    uk colchester
    Is that yours 80b
     
  15. optima21 Forum Supporter

    Messages:
    2,483
    Location:
    halifax, England
    slim_boy_fat and Cornwallfrank like this.
  16. The_Yellow_Ardvark

    The_Yellow_Ardvark If in doubt ask.

    Messages:
    9,702
    Location:
    UK
    Learn to weld.
    Practice and practise.

    Seek help if you need, some local fabrication shops may take on small cash in hands hobs for the critical parts.
    2 place near me will, if you ask them in advance and ask nicely.
     
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  17. stuvy

    stuvy Member

    For the time it takes to be proficient in welding and to a safe standard your best off paying someone to make it for you rather than risking life and limb

    Box is old hat and doesn’t have the same strength at tube

    Any builder worth his salt knows that granted lots of older cars have box but it’s just that OLDER cars. Technology has moved on
     
    carbon likes this.
  18. The_Yellow_Ardvark

    The_Yellow_Ardvark If in doubt ask.

    Messages:
    9,702
    Location:
    UK
    But box is easier to shape and weld.

    I have seen a few self built cars made from box and they were not to bad.

    If the OP wants to try and get good enough to weld we should let him.
    The IVA will advise him on what to do.
     
  19. The_Yellow_Ardvark

    The_Yellow_Ardvark If in doubt ask.

    Messages:
    9,702
    Location:
    UK
    Oh yes, additional to0 the above.
    Then charge him to tell him.
     
  20. pedrobedro

    pedrobedro Man at Matalan

    Messages:
    9,514
    Location:
    CX Derbyshire
    What engine are you going to pull this round with ? You don't need thick wall tubing the strength is not in the wall thickness and weight is a big component in any form of racing. Cut down on tube size and put more in to strengthen it.

    Caterham and Westfield and all the other kit suppliers use RHS, I think that's what he means by box. Round tube presents problems cutting fishmouths and working out angle where square tubing is easily joined as you work in one plane most of the time.
     
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