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shorten a truck frame

Discussion in 'The Hokey Ass Message Board' started by chopshopboss65, Apr 6, 2006.

  1. chopshopboss65
    Joined: Apr 4, 2006
    Posts: 75

    chopshopboss65
    Member

    what is the best way to cut a frame to shorten it, straight up and down, at a angle, or notched?

    thanks

    Richard
     
  2. tommy
    Joined: Mar 3, 2001
    Posts: 14,738

    tommy
    Member

    I took 11" out of a suburban frame. I cut it striaght and square.

    Sometimes people confuse glueing (as in wood) with welding. Glueing requires surface area.

    Welding does not. A properly executed weld will be stronger than the parent metal. The important part of that statement is...properly executed. Bevel the joint for 100% penetration. Unlike glueing there will be no crack remaining after its welded correctly. If the weld is a bridge across the old joint, it was not done right.
     
  3. porknbeaner
    Joined: Sep 12, 2003
    Posts: 25,741

    porknbeaner
    Member

    I always cut 'em at an angle, but that's the way I learned to do it. I've seen 'em done both ways and both have held up just fine.
     
  4. RacerRick
    Joined: May 16, 2005
    Posts: 2,742

    RacerRick
    Member

    I am lengthening a frame in a few weeks and have been told that putting a diamond shaped plate over the weld and fully welding that is a good idea.
     
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  5. chrisntx
    Joined: Jan 20, 2006
    Posts: 1,761

    chrisntx
    Member
    from Texas .

    Modernbeat sez the diamond is old technology. He sez to apply a square or rectangle with welds running across ONLY. I dunno. Ask him. :)
     
  6. eberhama
    Joined: Dec 19, 2003
    Posts: 528

    eberhama
    Member

    I straight cut mine, and plated the inside with a rectangular plate. I had a certified welder do the welding though. I think it will hold just fine, but haven't had it on the road yet.
     
  7. tommy
    Joined: Mar 3, 2001
    Posts: 14,738

    tommy
    Member

    I put a diamond gusset over the weld on the inside mainly beacause it doesn't hurt and I think it looks cool.:D (I ground the weld smooth on the outside so it could not be detected) It was a 3/4 ton 4X4 and last I heard it was still pulling the mountains of West by god Virginia.

    You can cut it in a zig zag. That doesn't really matter. I'm just saying that how you cut the frame will have no effect on the strength of the joint with everything else remaining the same. So why make it harder on yourself?
     
  8. deuce295
    Joined: Dec 9, 2005
    Posts: 211

    deuce295
    Member

    A weld is normally strongest when loaded in shear as opposed to tension. Granted the weld is going to be stronger than the parent metal if done right but the stress loads are handled better in a shear joint. Thats the way a splice in an aircraft fuselage is required to be welded (angled rather than straight up and down) and we have been doing it that way forever. Could be wrong I guess but just my 2 cents. I'm sure a straight cut with a welded doubler plate welded length wise will be easily as strong as the rest of the frame.

    Jim
     
  9. chopshopboss65
    Joined: Apr 4, 2006
    Posts: 75

    chopshopboss65
    Member

    thanks all just needed some input to make myself feel better before i did it. i broke the frame on my work truck and we weld it back and plated it on the inside, they burned a couple holes in it and welded those closed, i tow all sort of cars and trucks with it and still doing good.

    thanks again

    Richard
     
  10. bigdog
    Joined: Oct 30, 2002
    Posts: 368

    bigdog
    ALLIANCE MEMBER

    When the frame on my big truck('68 Chevy C-50) was lengthened for the installation of the tilt bed they cut the frame straight, welded, then plated over it. If you look at the big commercial trucks this is how they do them. If it's sturdy enough for the loads they haul nothing we do is going to break a frame done that way.
     
  11. The OEM seams are always vertical,
    not at an angle,or with reinforcing plates.
     
  12. Dale Fairfax
    Joined: Jan 10, 2006
    Posts: 2,586

    Dale Fairfax
    Member

    Am I missing something?I've never seen an O.E.M. frame with a joint in it.











     
  13. Dale Fairfax
    Joined: Jan 10, 2006
    Posts: 2,586

    Dale Fairfax
    Member

    You're dead on! And that's the reason for diamond shaped gusset plates straddling a vertical joint. (When working with truck frames a vertical cut line is more precise, easier to control, and quicker.) The diamond shaped plate insures that the welding is in a (nearly) horizontal orientation and thus loaded in shear. Any commercial truck body company that I've dealt with always did it that way.





     
  14. krooser
    Joined: Jul 25, 2004
    Posts: 4,591

    krooser
    Member

  15. modernbeat
    Joined: Jul 2, 2001
    Posts: 1,229

    modernbeat
    Member
    from Dallas, TX

    On diamond gussets, just because it was done in the past, and folks still do it today, that does not make it the best method.

    The best gussett would be to flush weld the two parts of the frame together, then use a rectangular gussett and only weld the two sides that parallel the direction of the frame rails. Do not weld the two edges perpendicular to the frame.

    Now, if you've got some goal other than having the strongest, longest lasting gussett, then do something else. If you want to be "pretty" or "old-school" use a diamond. ;)

    BTW, what happened to all the old posts? I was going to link to some circa 2002 stuff, but couldn't find it.
     
  16. Wild Turkey
    Joined: Oct 17, 2005
    Posts: 899

    Wild Turkey
    Member

    I've seen a truck bed break because of two short vertical welds -- it was in a high stress area and the square corner caused the stresses to focus in one area ("stress riser, IIRC) and it cracked.

    Crack grew until member was broken, transfering load to adjacent members, which couldn't handle the load - - - :eek:

    That's why you only weld horizontally on frames.

    The old "diamond" was an attempt to avoid verticle welds and spread the stress.

    Anybody else ever seen a weld end with a "curlyque" -- also a way to avoid stress concentration.:cool:


    just this old welder's too scents:D
     

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