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rear frame Z'ing angle

Discussion in 'The Hokey Ass Message Board' started by SledKicker, Oct 23, 2012.

  1. SledKicker
    Joined: Sep 8, 2012
    Posts: 34


    When z'ing a stock model a frame 8 inches in the rear, is there any reason i can't just do it in the style of a simple "cut and stack" style step? I mean, just cut straight, put a 4 inch piece of tube steel in between the pieces before welding it back making a "straight" up and down step up of about 8 inches?

    I believe I've seen t buckets use straight up and down rear Z's, but most custom frames i see under model a's use a sloped rear Z, which would be much more difficult for me and would create issues keeping my stock frame length.

    I'm obviously new to this so be gentle.
  2. Draw it out.
    You've explained it correctly then you lost it some place along the way.
  3. el Scotto
    Joined: Mar 3, 2004
    Posts: 4,357

    el Scotto
    from Tracy, CA

    Pick any angle you'd like, here's an example of a simple "traditional" Z.

    Hot rodders weren't rocket scientists, they were 16 year olds with stick welders and oxyacetylene torches. ;)

    I'd add a plate across the outside as cheap insurance and box the rear, assuming you're using a stock frame and not tubing.

    Good luck! :)

    Attached Files:

  4. SledKicker
    Joined: Sep 8, 2012
    Posts: 34


    I realize it was hard to explain. I mean to do something like that, el Scotto, but instead of putting the sections right back on top of each other and welding em up, I'd put in a piece of tube steel and effectively double the height of the step but without a slope.

  5. bonechip67
    Joined: Mar 3, 2009
    Posts: 82


    El Scottos right, they built them all kind of ways and with no engineering degrees! Ive seen them several ways but always built mine with a slant. I think you can get away with what you want to do since its only 8 inches. I would strongly suggest welding in some gussets just to make sure its good and strong.
  6. SledKicker
    Joined: Sep 8, 2012
    Posts: 34


    of course, gussets were in the plan from the get go as i'm not fond of dying. :)

    thanks bonechip
  7. rpu28
    Joined: Jan 17, 2006
    Posts: 144

    from Austin

    Z-ing at a right angle puts a lot of vertical stress on a short, vertical weld. The weight of the body and driving forces want to shear the frame at the vertical weld at the top of the Z. Stress is better distributed with an angled Z, and the weld is longer (i.e. akes more stress to cause it to fail).

    But if you use gussets inside the right angles and/or box the Z'd section and/or fishplate the weld areas, you can have plenty of strength to cover up for the right-angle Z.

    Personally, I'd box the frame from at lease three feet in front of the crossmember all the way to the crossmember, and I'd add some modest C-channel gussets as well.

    Remember that a stock Model A frame is not particularly strong, and the weight on the real of a Model A body is relatively small.
  8. -Brent-
    Joined: Nov 20, 2006
    Posts: 6,019


    If you're doing this to an existing frame, you run the risk of shortening it.

    With my kick-up it worked out because we were fabbing something new and could fit the kick-up to the dimensions we needed. I'd look into something more along the lines of kicking the frame up rather than a z.


    Kicked-up, not Zed.

    Attached Files:

  9. all thumbs
    Joined: Dec 11, 2010
    Posts: 7

    all thumbs

    Not an A-frame, but i think what you're after

    Attached Files:

  10. When I "Z" a frame I use a 6x3 section of tubing that I notch on each end to box the end of the frame. I use a 30 degree angle just because that was how I was taught 30 years ago.

    Attached Files:

    Simon Driscoll likes this.
  11. gimpyshotrods
    Joined: May 20, 2009
    Posts: 18,023


    45º. This is 6". Gusseted inside.
  12. here's mine...I fishplated at all joints of kickup

    Attached Files:

  13. rjgideon
    Joined: Sep 12, 2005
    Posts: 540


    I think he's asking about a 90* kick. NVRRDUNN showed what he's looking for.
  14. sskustoms
    Joined: Jun 18, 2007
    Posts: 277


    45 works for me and also make fish plates and you should be good also leave extra length on kick up going back to trim later when setting wheel base
  15. kennb
    Joined: Jan 8, 2008
    Posts: 178


    You can do it straight up 90 degree, but make sure it's gusseted. Remember there is more strenth in triangles, a lot more. Rpu28 is correct in what he said about stress in right angles. Ken
  16. A stock model A frame ,
    Square cut,
    Square piece,
    Retain Stock wheel base.

    The extension will have to go on top of the Long forward main section,
    The rear part of the frame would need to go to the side of the extension.
    Doing it opposite would require 1 angled cut to match the taper if the frame or flattening the taper.

    That could be done.
    Seems easier to just angle cut the extension and weld it on top of the main rail and underneath ( as opposed to the side) the rear section of frame.
  17. SledKicker
    Joined: Sep 8, 2012
    Posts: 34


    There is so much good info to be had here. thank you all.
  18. SledKicker
    Joined: Sep 8, 2012
    Posts: 34


    I think im going to do a 45 cut on each end and go with a 90 degree whole frame with some 10 gauge plates and gusset/plate my new joints

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