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Front knuckle (lower half) swing check bolt length setting

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  • Front knuckle (lower half) swing check bolt length setting

    I'm looking at four different front knuckles for my WM300 (two left and two right) and the length of the spot welded swing stop bolts are all different lengths. I have to replace one of my front knuckles. Is there a standard factory setting for the length of this bolt or do I just grind the spot weld off the replacement knuckle and set the length of the bolt at the same length as the one I am replacing and spot weld it? Seems strange there is so much difference. I assume any replacement bolt should be grade 8? Thanks.....Keith.

  • #2
    Keith,

    I looked in my shop manual for my 1949 B-1-PW and I also looked in my M37 Power Train, Body and Frame manual, and neither one of them gives any indication of the protruding length of the bolt. They both indicate the need to use a wedge-shaped tool between the knuckle and the axle housing to determine the amount of rotation of the knuckle. With the tool placed against the surface of the knuckle where the felt seal goes (and felt seal removed), the knuckle is rotated until it wedges that tool against the axle housing. The tool prevents the knuckle from rotating too far. With the knuckle in that position, still holdiing the tool, the bolt must be extended till it lightly touches the axle housing, and the lock nut is tightened to hold the bolt in place. Then the bolt gets welded to the nut, and the nut gets welded to the knuckle. The only problem is there is no description of the dimensions of this tool, and I'll bet this tool is as rare as hen's teeth.

    My Power Wagon manual also makes mention of using floating tables, with each inside wheel at an angle of 28 degrees. I don't know what a floating table is, except that I think it would be something a magician might use, but I just now eyeballed the angle between the plane of the drum backing plate (the wheels are off my truck right now) and a plane that is perpendicular to the left-right axis of the axle housing on my truck, using a protractor-type device that I have, and it looks like the included angle is pretty darn close to 28 degrees. I don't know that even this will help you, but I figured it couldn't hurt.

    Lastly, I used my dial calipers to take a measurement of the bolt length on each knuckle (left and right) on my Power Wagon, and the left side came out to be about 0.965" and the right side came out to be about 0.935". This is from the flat face of the bolt head (the surface that contacts the axle housing) to the knuckle housing. It was a little difficult to take this measurement because of stuff in the way, and because the exact location of the knuckle housing is not completely well-defined because of the weld that is present right where I was trying to measure, but it should be close. I'm wondering if my measurements are close to any of yours from your four knuckles.

    Having said the above, there must be some reason Dodge did not specify a bolt length. Maybe it's because the adjusted length may vary depending on wear in the knuckle bearings? Or maybe the difficulty in measuring the length of an assembly that's already been welded is difficult to do accurately, as evidenced by the difficulty I just experienced? I'm not sure, but it doesn't seem like it would be THAT critical, but someone may come along and tell us both why I'm wrong. In any case, I hope this is of some help.

    If your existing adjustment was working, then maybe you could adjust the new setup the same way as the existing one? I believe one of the primary concerns with too tight an angle/turn radius is that the Tracta universal joints inside the knuckle may not hold for long, but if it was working before, and depending on if you know that the front drive was actually being used a lot, then that might be a good enough approach.

    Good luck!

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    • #3
      Floating table

      I suspect that a "floating table" would be the fancy name for the "lazy Susans" that were once part of every alignment shop's arsenal.
      I don't know but it's my best guess.
      Last edited by Jeremy Horvath; 02-24-2017, 09:54 PM. Reason: Typo

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      • #4
        Front knuckle (lower half) swing check bolt length setting

        Thank you Matt and Jeremy! I appreciate your kind responses. I will measure and post with the various lengths among the knuckles I have. Matt, off the top of my head, your measurement sounds close to the one I am replacing. I will set the bolt length identical with the knuckle I am replacing as you recommend. Never a dull moment with these trucks.....Keith.

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        • #5
          Originally posted by Jeremy Horvath View Post
          I suspect that a "floating table" would be the fancy name for the "lazy Susans" that were once part of every alignment shop's arsenal.
          I don't know but it's my best guess.
          Ok, that's probably what it is. I've never worked in an alignment shop, so wasn't familiar with that.

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          • #6
            Originally posted by Hartman View Post
            Thank you Matt and Jeremy! I appreciate your kind responses. I will measure and post with the various lengths among the knuckles I have. Matt, off the top of my head, your measurement sounds close to the one I am replacing. I will set the bolt length identical with the knuckle I am replacing as you recommend. Never a dull moment with these trucks.....Keith.
            Hopefully we have helped. Good luck!

            Comment


            • #7
              Front knuckle (lower half) swing check bolt length setting

              Matt:

              I measured the knuckles that I have and the bolt settings are all over the place as follows:

              1. the one I am replacing- .850";
              2. the others come in at 1.095", .995",
              1.035", and finally an outlier at .650".

              Keith.

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              • #8
                That is interesting, Keith. I would say they are all within the ballpark of each other, centered around an average value that is close to what I measured, except that last one, as which as you mentioned, is kind of an outlier.

                It may be fine to adjust the new ones to the same values as the old ones, but if you want to err on the side of caution, you could open them up to a little larger value.

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