Alignment jig and first alignment

So, I made my own alignment jig.  Its a clone of a well known string setup.  These brackets hang off of the inner trunk and hood lips.  Their whole point is to hang a bar down at axel height at the front and rear of the car.  The bars are designed to have grooves on the ends to hold a string.  The grooves are exactly the same width in the front and rear.  A string is placed in the groove front to rear so that the strings left and right are exactly parallel to each other.  Once the strings are lined up with the axels, they are exactly parallel to the car’s axis.

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So, to make this thing you need the following:

  • 2 – 8ft lengths of 1” x 1/8” aluminum
  • 1 – 3ft length of 1” x 1/8” aluminum
  • 1 box of #10 x 1/2” pan head screws, and nuts
  • 2 lengths of 3/4” EMT conduit
  • 4 conduit set-screw unions (home depot has the ones with a groove like they are pictured below
  • 1 roll of 1” wide adhesive padding
  • 1 set of 4 galvanized steel mop/broom holders (Ace Hardware)

The front hangers have bends at the following lengths starting at the top:

  • 1/2”
  • 1”
  • 8 1/2”
  • 14”

The rear hangers have one more bend than the rears:

  • 1/2”
  • 1”
  • 3”
  • 10 1/2”
  • 13”

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The adjustment slot is 3/16” wide and 5” long.  It starts 4” from the bottom of the hanger.  Finally, the cross members are 23” wide.

 

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The conduits are cut at 68” long.  Then the unions are attached to the end so that the grooves are exactly the same distance apart for both the front and rear conduit.  It doesn’t matter exactly how far apart they are…just be sure that they match.

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Finally, I padded the underside of the parts that could make contact with the car paint.  I also put all the screws in from the back in order to keep the screw ends and nuts from rubbing against the car paint.

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Next I used some 20 lb test fishing line to create the strings, and attached them to plumb bobs as weights.  Tie a 2” long loop in the fishing line to loop over the conduit ends.  The plumb bob hangs over the other conduit.

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Next up, I created some leveling platforms out of 2x material.  I used 2×12 for the top and 2×8 for the sides.  They are 24” long, and 11 1/4” wide (the width of the 2×12).  Then I drilled some 7/16” holes for the legs and hammered 3/8” T-nuts into the holes, and screwed 3/8” x 1 1/2” bolts into the T-nuts.

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In order to keep the suspension from binding up I made 4 slip plates by using 2 industrial linoleum tiles per tire with a layer of grease between them.  This allows the tires to slide in and out as camber/caster/toe adjustments are made.

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Next up, how to use these to align car (as best as I know how).

4 comments to Alignment jig and first alignment

  • The main thing is to not let the car slide off the blocks while on the greased linoleum plates!!

  • John

    Tom,

    We are starting to align our miata for first time this week. How do you like the platforms……and how stable are they with car up on them??

  • John Mueller

    Neat. Thanks.
    How did you cut the adjustment groove? Dremmel?

    • Tom

      Hey John-

      I cut the groove using a table-saw. Its a bit nasty cutting aluminum with a tablesaw, but it works, and it doesn’t damage the carbide blade. Having a fine tooth plywodo blade helps. Going very slowly helps, too.

      I drilled holes where the end of the slots would be. I slowly let the aluminum down onto the TS blade, and then fet it back and forth to cut one half of the slot. then flip the piece around and repeat the operation. I ended up with a bunch of aluminum shards all over me. Definately use safety eye protection!

      Finally I used a file to clean up the rough edges at the ends.

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