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Frame tubing

Discussion in 'The Hokey Ass Message Board' started by poofus1929, Nov 17, 2009.

  1. poofus1929
    Joined: Jan 29, 2008
    Posts: 897

    poofus1929
    Member
    from So Cal

    I'm pondering what tubing thickness to buy. 2x3 and 2x4 .120 wall seems kind of thin to me. Has anyone had any problems in strength using .120 wall?
     
  2. theHIGHLANDER
    Joined: Jun 3, 2005
    Posts: 8,300

    theHIGHLANDER
    Member

    Drag cars are normally tubbed with .083 2X3. Bracing and cross members make strength as well as good sound engineering. Think it through. 120 is plenty strong.
     
  3. poofus1929
    Joined: Jan 29, 2008
    Posts: 897

    poofus1929
    Member
    from So Cal

    Your right. I was just tinkering out in the garage and a stock A frame is .156 and that is what got me thinking.
     
  4. Pat Pryor
    Joined: May 28, 2007
    Posts: 1,877

    Pat Pryor
    Member

    i do 2x4 1/8'' thats suitable for replicating model A frames. but it depends on what your doing 2x3 is fine also for just a basic frame for Tor A
     

  5. scootermcrad
    Joined: Sep 20, 2005
    Posts: 12,375

    scootermcrad
    ALLIANCE MEMBER

    .120 is fine in most cases. HOWEVER... we really need to know what you're building. Is this a frame for Semi or a frame for a t-bucket? Will the powertrain be a Pinto Motor or an Allison V-16? Know what I mean?

    There are a ton of threads on this also.
     
  6. poofus1929
    Joined: Jan 29, 2008
    Posts: 897

    poofus1929
    Member
    from So Cal

    T Coupe, Either a flatty or sbc, What ever money allows for.
     
  7. fms427
    Joined: Nov 17, 2006
    Posts: 864

    fms427
    Member

    Yep, .120 or .125 plenty strong. I generally use 2X4 for cars without cages, 2X3 (usually .083) for cars with cages. Nothing has bent yet - some even crash tested :eek: !!!
     
  8. scootermcrad
    Joined: Sep 20, 2005
    Posts: 12,375

    scootermcrad
    ALLIANCE MEMBER

    2x3x.120 would be a safe bet. Cross bracing might vary based on target performance, but shouldn't need anything crazy unless you plan on beating this thing up pretty good and sticking a high HP SBC in there. Then you might want to increase it to 2x4x120.

    Keep in mind this stuff is boxed already. A-frames were C-type construction and really the car was designed to have some flex to it.
     
  9. Sufficent.ore than even. Donr forget it is box or rectangular tubng two side make for 1/4 inch. Most old frames are channel so this is much stronger.
    Don
     
  10. dreracecar
    Joined: Aug 27, 2009
    Posts: 3,218

    dreracecar
    Member
    from so-cal

    When was the last time anybody "miked" tubing thickness?
    .120 wall round tubing measures at .114, thats why if anybody is going to make a nhra legal cage in mild steel they go with .134 wall. Never go by what the rack says.
     
  11. bdynpnt
    Joined: Feb 9, 2009
    Posts: 354

    bdynpnt
    Member

    i built a 18 foot deck with a 5 ft tongue car trailer using 2x4x.120 and hauled some heavy assed stuff on it and never had anything bend so yes .120 wall is plenty strong
     
  12. onlychevrolets
    Joined: Jan 23, 2006
    Posts: 2,307

    onlychevrolets
    Member

    my frame is .120 wall....
     
  13. 35mastr
    Joined: Oct 26, 2007
    Posts: 1,899

    35mastr
    Member
    from Norcal

    Mine is alot beefier than that. But I like to be able to tap and thread holes when needed. Its .250. I know its going to be heavier,But I think the car will also ride alot better.
     
  14. narducci
    Joined: Jan 3, 2008
    Posts: 194

    narducci
    Member

    I'm using .187 wall for my frame . 3/16" thick 4 x 2 is 2# per foot more than 1/8". If you have 25' of tubing, we are talking 50# extra. In the grand picture, 50 # or $50 isnt going to make or break the project
     
  15. krooser
    Joined: Jul 25, 2004
    Posts: 4,584

    krooser
    Member

    More beef makes for a stronger frame... the ride is usually better because there's less flex allowing the suspension to do it's job. That being said, I've built several race cars with .120 rectangular tubing and it was pretty much the standard for that application at the time.
     
  16. Koz
    Joined: May 5, 2008
    Posts: 2,388

    Koz
    Member

    I use .120. I find the .120 has a radius on the edge much colser to a stock A or even '32 rail than .125. As you know, the thicker the wall the larger the radius on the bend. It's just the look. I've never broken one, (knock on wood), of the 50 or so I've built, and yes, one ot two have been crash tested. In the ultamate sense, the idea is to produce acceptable levels of safety margin and the least possible weight. Create strength through engineering as opposed to "railroad construction". 120. is fine.
     
  17. scottybaccus
    Joined: Mar 13, 2006
    Posts: 4,109

    scottybaccus
    Member

    OE rails for a Model A are heavier because they were never intended to be boxed. Having 4 sides on a rail allows thinner material. 11 gauge is pretty typical. That's .1196".
     
  18. jaxx
    Joined: Mar 22, 2008
    Posts: 397

    jaxx
    Member

    I used .120 - 2 x 3 for my frame rails and .250 2 x 2 for front cross memder - 25/26 dodge rpu frame with plans of a 225 slant six but have changed my mind to upgrade to a small block mopar so I added a 1/4 in x 3 plate liner to the inside of my frame rails for sheer strength - that'll fix it - frame pic in my profile - Jaxx
     

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