Miller Electric

Welding Discussion Forums

Home » Resources » Communities » Welding Discussion Forums
 
Miller Welding Discussion Forums - Powered by vBulletin

Results 1 to 10 of 10
  1. #1
    Join Date
    Apr 2010
    Posts
    1

    Default Welding/Repairing cracks on car frame

    Im doing some repairs on the front end of a drag car, and were I am working the frame has some cracks in it. I was always told to drill a small hole at the end of the crack to prevent it from spreading, once thats done then it can be welded. Just wondering if this is true or if anyone has any other suggestions. Anything will help. Thanks.

  2. #2
    Join Date
    Jan 2010
    Location
    Paris, Ontario
    Posts
    23

    Default

    ya u can drill your holes if you want the best bet is to remove all weld metal that is cracked. If its not the welds ,gough the cracks out with a small zip wheel or sumthin like that evan a file cause u are working on a tube chassis car or no?

  3. #3
    Join Date
    Dec 2005
    Location
    wisconsin
    Posts
    836

    Default

    In the aviation world on tubing structures, the normal procedure is to drill the ends of the crack as you mentioned, and installing a sleeve over the cracked area and welding the sleeve in place. There is actually a very detailed manual on tubing repair titled AC43.13-1B do a google search and download the PDF from the FAA. Tubing repairs start at page 4-80 I believe.
    "Better Metalworking Through Research"

    Miller Dynasty 300DX
    Miller Dynasty 200DX
    Miller Spectrum 375 extreme
    Miller Millermatic Passport

    Miller Spot Welder
    Motor-Guard stud welder

    Smith, Meco, Oxweld , Cronatron, Harris, Victor, National, Prest-o-weld, Prest-o-lite, Marquette, Century Aircraft, Craftsman, Goss, Uniweld, Purox, Linde, Eutectic, and Dillon welding torches from 1909 to Present. (58 total)

  4. #4
    Join Date
    Feb 2009
    Location
    Maryland
    Posts
    707

    Default

    On light truck frames, the procedure is similar to what was mentioned for tubes.

    A crack on a flat surface is reinforced by a diamond shaped plate. Same thickness as parent metal. If the crack is 3" long, make a square that is 3.5" in the diagonal and have the diagonal cover the crack (you will have to grind down the weld - so a 100% penetrating weld is preferred.)

    The idea is to spread whatever stresses caused the first crack around a bit.

    If you weld a square plate over the crack, with square edges parralel to the crack, the same forces that made the first crack will now be concentrated at the edge of the square plate. If you rotate that square plate 45 degrees, the stress risers will be at 45 degrees to the original crack - effectively spreading them out.
    ''/\
    / | \
    \ | /
    _\/

    Where the vertical line is the original crack. Call it a diamond, call it a square rotated, (call it a rhombus). whatever.
    Last edited by con_fuse9; 04-14-2010 at 10:10 AM.
    Con Fuse!
    Miller Dynasty 350
    Millermatic 350P
    -Spoolmatic 30A

    Hypertherm PowerMax 1000G3
    Miller Multimatic 200 - awesome portable MIG (and stick and TIG)
    Miller Maxstar 200DX - portable TIG and stick

  5. #5
    Join Date
    Feb 2010
    Location
    Houston, Tx.
    Posts
    378

    Default

    Whatever method of repair that you choose, you really should invest in a penetrant dye check system. These are cheap compared to other crack detection methods and do a pretty good job. The dye system will show you how far the crack really goes and where it starts and stops, so that you may repair the entire cracked area.

  6. #6
    Join Date
    Dec 2005
    Location
    wisconsin
    Posts
    836

    Default

    Quote Originally Posted by davinci2010 View Post
    Whatever method of repair that you choose, you really should invest in a penetrant dye check system. These are cheap compared to other crack detection methods and do a pretty good job. The dye system will show you how far the crack really goes and where it starts and stops, so that you may repair the entire cracked area.
    Great until you go to get all of that ultra thin oil out of the crack for cleaning
    "Better Metalworking Through Research"

    Miller Dynasty 300DX
    Miller Dynasty 200DX
    Miller Spectrum 375 extreme
    Miller Millermatic Passport

    Miller Spot Welder
    Motor-Guard stud welder

    Smith, Meco, Oxweld , Cronatron, Harris, Victor, National, Prest-o-weld, Prest-o-lite, Marquette, Century Aircraft, Craftsman, Goss, Uniweld, Purox, Linde, Eutectic, and Dillon welding torches from 1909 to Present. (58 total)

  7. #7
    Join Date
    Feb 2010
    Location
    Houston, Tx.
    Posts
    378

    Default

    Point taken. I prefer magnaflux, but he's probably not going to go that far. Or you could just drill holes where you think the crack ends and weld it up with the unidentifiable rod you found in the back of your uncle's garage, then go 200 m.p.h. down track. You weld on aircraft, you know what I was getting at.
    Last edited by davinci2010; 04-15-2010 at 03:51 AM.

  8. #8
    Join Date
    Dec 2005
    Location
    wisconsin
    Posts
    836

    Default

    Quote Originally Posted by davinci2010 View Post
    Point taken. I prefer magnaflux, but he's probably not going to go that far. Or you could just drill holes where you think the crack ends and weld it up with the unidentifiable rod you found in the back of your uncle's garage, then go 200 m.p.h. down track. You weld on aircraft, you know what I was getting at.
    Yep, I know. So many things are a "double-edged sword" when it comes to repairs. On aircraft repairs, standard methods say you dont even weld the crack up. Just stop drill it ( just beyond the end of the visible crack ), and weld the reinforcement patch/sleeve over it. There is a lot more to it than that though as it depends on the crack location, and size.
    "Better Metalworking Through Research"

    Miller Dynasty 300DX
    Miller Dynasty 200DX
    Miller Spectrum 375 extreme
    Miller Millermatic Passport

    Miller Spot Welder
    Motor-Guard stud welder

    Smith, Meco, Oxweld , Cronatron, Harris, Victor, National, Prest-o-weld, Prest-o-lite, Marquette, Century Aircraft, Craftsman, Goss, Uniweld, Purox, Linde, Eutectic, and Dillon welding torches from 1909 to Present. (58 total)

  9. #9
    Join Date
    Feb 2010
    Location
    Houston, Tx.
    Posts
    378

    Default

    Agreed. I've had mixed results with stop drilling in non critical projects when using only my eyes to identify the start and stop of a crack. I think if it is a tube chassis, and tech o.k.s the location of the repair I would go with your idea and sleeve it. He did not specify what class he is running in, or where in the front end the crack is. Tech inspectors may get a little picky on this one, even if the frame is not ever cut or actually seperated. They may consider a sleeve a splice or a joint. I would check with a tech inspector first.

  10. #10
    Join Date
    Dec 2006
    Posts
    612

    Default

    Is it M/S or C/M?

    If the crack is not in the roll bar/Cage area I'll bet you will find the Tech guy won't say anything. I could be wrong, they may if it is an obvious hazard, but most times they are just interested in the tubes that protect the driver.
    The way it was explained to me......, they don't care if you wreck, only that you survive if you do.
    If you look at an SFI chassis book, they only diagram the cage itself, However it is obviously in you best interest to make the repair safe.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

Warning: Function split() is deprecated in /mnt/stor3-wc1-dfw1/357822/357839/www.millerwelds.com/web/content/lib/footer.inc.php on line 82

Welding Projects

Special Offers: See the latest Miller deals and promotions.