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The tool is just a "C" jig that is made from some 1/2 pvc . 3 pieces and two elbows.... 2/4" pieces and 1/14" piece. [ $2/3]
Many use a level/board across the tire sidewall, but that is not accurate and the buldge of the tire , runout.etc , just doesn't make it .
so , if you make a stand-off, square 'C' fixture w/pvc , only the ends of the pvc will make contact with the rim of the wheel.This get the plumb out away from the car and tire where you can read it.
The long piece connects to the two shorts w/90 elbows and the overall tool length should be the same measure as the rim edge of the wheels the tool is to be used on. [ for 113, that is 14"]
Now. you drill a hole through the top pvc 4' pipe at 3" from the end that rest on rim. Then mark the bottom 4" piece at exactly 3" from that ones end. The top hole goes through the side of pvc c/l and the mark on the bottom one is on the side. Put a fishing line [mono] through the hole and hang a plumb bob on the line a couple of inches below the bottom piece, so the line pendulums across the lower marker.
The tool can be checked by holding it in your fist by the long pvc piece against any true perpendicular surface to make sure you plumb settles at exactly where your lower marker line is. [ I use a fine marker for this indexing mark] Once you have that established , you simply mark off a couple more index marks +/- from your known plumb mark [ two are enough] at exactly .2618" on each side of the original.. This is the inch measure for the tangent angle of 1 degree at 14" [ which is why you want the plumb line exactly 14' from the hanging hole to the index marker .. which is one of the reasons for the hole coming out the side of the pvc, etc]
I you want the tool for other measures , you have to find the tangent angle from a trig chart for different wheel rim size.
That's it .. grab the tool in your hand by the long pvc section , hold the two ends up against the rim edge , vertically, with just enough room for the Bob to swing freely past the index marks , and when it settles, read where it is in reference to the index markers on the botton leg of the tool. At zero camber , it will register plumb. At one index mark away from car , it will be 1 degree + camber. Toward the car , neg camber , etc...
The trick is to make sure the car itself is level from r/l before taking camber readings , as the tool plumb is in relation to level, as any plumb is...
As you can see , with a 1 degree index spacing increments of over 1/4 " , a 30' calibration is easily recognised..the tool is as accurate as your construction tolerences are.
Don't forget the wheel bearings adjust before testing camber specs.
Clear as mud ??
My scanner has crapped , so no pics.
